1995 overview
Massachusetts Water Resources Authority · from the MWRA · 66 pages · 4.1 MB
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Massachusetts
Water Resources Authority
MWRA Environmental Quality Department Technical Report
Series 97-2
Outfall Monitoring
Overview Report: 1995
May 199°
Prepared Under the Direction of:
Douglas B. MacDonald, Executive Director
John F. Fitzgerald, Director, Sewerage Division
Board of Directors:
Trudy Coxe, Chair
John J. Carroll, Vice Chair
Michael Benullo
Lorraine M. Downey, Secretary
Norman P. Jacques
Charles Lyons
Joseph A. MacRitchie
Vincent G. Mannering
Donald A. Mitchell
Samuel G. Mygatt
Marie T. Turner
OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
Outfall Monitoring Overview Report: 1995
May, 1997
Technical Report No. 97-2
Environmental Quality Department
Massachusetts Water Resources Authority
Report Contributors:
Donald P. Galya — ENSR
Rebecca Zavistoski — ENSR
Isabelle Williams — ENSR
Michael S. Connor — MWRA
Michael Mickelson — MWRA
Kenneth Keay — MWRA
Maury Hall — MWRA
Stephen Cibik — ENSR
Windsor Sung — ENSR
David Mitchell — ENSR
James Blake — ENSR
Joshua Lieberman — ENSR
Steven Wolf — ENSR
Brigitte Hilbig — ENSR
John Bleiler —ENSR
Kenneth Hickey — ENSR
Report Layout and Graphics by:
Kim Loosen — ENSR
Ilse Stryjewski — ENSR
Citation:
Galya, D.P., et al. 1997. Outfall Monitoring Overview
Report: 1995, MWRA Enviro. Quality Dept. Tech. Rpt. Series No. 97-2.
Massachusetts Water Resources Authority, Boston MA. 61 pp.
MWRA + OUTFALL MONITORING OVERVIEW REPORT: 1995 /I
Table of Contents
Executive Summary
1.0 Introduction... 00... c cece cece eee ete e nee need 01
Ll Report objectives and content... 0.0.6... cece eee eee ee Ol
1.2 Background 0.0... ccc cece eee teenies 02
13 Trigger parameters and thresholds............ 00sec eee ee eee 03
14 Monitoring program summary ....... 0.2.00 beeen eee eee 04
15 Data management ..... 0... certs 06
2.0 Effluent Monitoring Program... 1.0.0.0 0 cece renee 07
2.1 Effluent issues... eee eee 07
2.2 Monitoring program design... 6.2.0.0... cere eee eee eee 08
2.3 Threshold comparison... 0... eee 09
24 Monitoring results... 2.0. eee eee 13
2.4.1 Effluent characterization... 6... cee eee ees 13
2.4.2 Pilot treatment plant results............... 00s eevee 16
3.0 Water Column Monitoring Program......... 06.0.0 e eee eee eee 17
3.1 Water column issues... 0... ee 17
3.1.1 Organic material... 0.6. 17
3.1.2 Nutrients... 00... eee 17
3.1.3 Toxic contaminants... 2.2.6... 18
3.2 Monitoring program design... 6.0.0... cee 18
3.3 Threshold comparison... 6... obec eee eee 20
3.4 Monitoring results... 0... eee eee 25
4.0 Benthic studies... 0... cece cece centre ene te tenet eens 33
4l Benthic issues... 00... eee tenes 33
Al. Nutrients... 00. eee 33
4.1.2 Toxic contaminants........... 0.0 ee eee eee eee eee 33
4.1.3 Solids and organic material... ........- 0.0 sees eae 33
42 Monitoring program design ........ 06.0 eee eee eee eee eee 33
4.2.1 Nutrient flux surveys 0... 0... eee eee eee eee 34
4.2.2 Soft-bottom surveys... 6... eee 35
4.2.3 Hard-bottom surveys 0.6... ee 36
43 Threshold comparison... ccc eee eee eee 36
II / OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
44 Monitoring results... 00.06. 40
44.1 Biological study results...... 000.000.000.000... 0000. 40
44.1.1 Boston Harbor... 0.0.0... ee eee 40
4.4.1.2 Massachusetts Bay... 2.0... eee 41
44.2 Sediment chemistry results ........... 000000002 eee 43
4.4.2.1 Boston Harbor... 0.0... ee 43
4.4.2.2 Massachusetts Bay.... 0... ee 43
5.0 Fishand shellfish oo... ccc cc cece cee et eee eee nee 45
5.1 Fish and shellfish issues.........0.000.000000 00 0c cece eee 45
5.2 Monitoring program design ........... 0.6. e cece eee eee 45
5.3 Threshold comparison... 2.0.0... es 46
5.4 Monitoring results... 2.0062 47
541 Flounder... 0.0... cece eee 48
5.4.2 Lobster... eee eee 49
5.4.3 Blue mussel... 2... 00.0. 49
References
Glossary of Terms
Acronyms
List of Tables
1-1 Summary of trigger parameters... 0.6... eee 03
1-2 Summary of MWRA monitoring program... .. 2.22.22. e eee ee 05
2-1 Effluent thresholds compared to 1995 monitoring results........... 10
2-2 Mean 1995 effluent contaminant concentrations compared to
adjusted water quality criteria... 66... eee 14
3-1 Water column thresholds compared to 1995 results............... al
3-2 Minimum DO concentration and percent saturation:
1995 and baseline period... 2.22... ee 22
3-3 Plankton thresholds comparison... 2.0... 00.2. eee eee 24
3-4 Shellfish monitoring stations for PSP... 6... eee 24
4-1 Benthic thresholds compared to 1995 monitoring results........... 37
4-2 1995 diversity data for the midfield stations...............0000. 37
43 Toxic contaminant thresholds and 1995 nearfield station data... .... 39
5-1 Fish and shellfish thresholds compared to 1995 monitoring results. . . . 47
5-2 Comparison of average body burdens of deployed mussels
for selected organic compounds and metals.................... 50
MWRA - OUTFALL MONITORING OVERVIEW REPORT: 1995 / Til
List of Figures
1-1 Distances of the new outfall from selected sensitive areas
in MA and Cape Cod Bays. 2... 0.0... eee eee eee 02
2-1 Total Nitrogen and particle particulate Organic Nitrogen
Loading in Deer Island Effluent... 6.2.0.0... 0c cece eee eee eee 13
2-2 Measurements of Fecal Coliform in Effluent .........0..0 000000000000. 15
3-1 Nearfield and farfield water column sampling locations.................. 17
3-2 Water quality modeling results near future outfall.................00004 22
3:3 Annual Water Column Cycle of Massachusetts Bay ...............000005 26
3-4 1995 daily precipitation and river discharge data... ...............2000. 27
3-5 1995 moored salinity sensor data... 0.0... cc eee eee 28
36 1995 moored temperature sensor data... ... 0.0... cece eee eee eee 28
37 1995 seasonal density cycle in the nearfield ........... 00.00 cece eee 29
3-8 1992-1995 chlorophyll a averages in the nearfield ...................0.. 29
3-9 Nearfield DIN concentrations for 1992-1995... 6... ee eee 30
3-10 1992-1995 dissolved oxygen cycle in surface
and bottom waters in the nearfield.. 0.0.0... 00.0000... 30
3-11 1992-1995 dissolved oxygen cycle in surface and bottom waters
in Stellwagen Basin. ©... es 31
3-12 Rate of decline of dissolved oxygen concentrations
in bottom waters in the nearfield. 0... ee 31
41 Benthic nutrient flux sampling locations.............. 0.0 ...000000005 34
4-2 Boston Harbor benthic sampling and sediment profile imaging station........ 34
43 Nearfield and midfield soft-bottom stations................00.000 0000 35
44 Nearfield and farfield soft-bottom benthic stations.................0 0005 35
4-5 Nearfield hard-bottom benthic survey transects. ...............-000 00005 36
46 Distribution of amphipod tube mats in Boston Harbor
from 1991 through 1995 2.2.6. 40
47 Soft-bottom benthic community diversities at nearfield
and midfield stations... 6. ees 41
5-1 Sampling stations for winter flounder, lobster and mussels during 1995. .... .. 45
5-2 Prevalence of CHV near the future outfall site: 1991-1995 ................ 48
5-3 PCB and mercury concentrations in flounder muscle :
and lobster meat, 1992 to 1995 60... eee eee eee 49
5-4 Total PCB bioaccumulation in mussels near Deer Island discharge, 1986-1995 . . 50
MWRA + OUTFALL MONITORING OVERVIEW REPORT: 1995 /i
Executive Summary
The people of the metropolitan Boston area, through the MWRA, are in the midst of an
ambitious program to upgrade their sewage treatment facilities and improve the quality of
Boston Harbor. This program includes the elimination of sludge discharges to the harbor,
construction of new primary and secondary sewage treatment plants, and relocation of the
current Boston Harbor effluent discharge points to a new location in Massachusetts Bay.
Sludge discharge ceased in 1991 and the new Deer Island primary treatment facility went
on-line in January 1995. In 1997, the first part of secondary treatment and in 1998 the new
effluent discharge outfall to Massachusetts Bay are expected to be operational.
A number of concerns have been raised regarding potential environmental impacts associat-
ed with the relocation of the wastewater discharge to Massachusetts Bay. In order to assure
that these concerns are addressed, MWRA developed a Contingency Plan and an outfall
monitoring program, and documented these in a series of reports. The Contingency Plan
(MWRA 1997) develops expectations for environmental quality in Massachusetts Bay and
Cape Cod Bay. The expectations are expressed as Caution and Warning Levels that would
trigger action if they are exceeded. Those trigger levels are compared to environmental
monitoring results in this report, the annual Outfall Monitoring Overview, which will also
describe any actions taken in response to an exceedance of a Caution or Warning Level
when the outfall is operational. The monitoring results are obtained following the proce-
dures detailed in a report called the Outfall Monitoring Plan (MWRA 1991, 1995).
The outfall monitoring program consists of two main phases. Baseline studies which com-
menced in 1992 are currently underway to document conditions before outfall relocation.
Post-discharge monitoring will commence in 1998; these studies will evaluate conditions
after the new outfall is operational. This report describes the baseline monitoring program,
summarizes and discusses the program results, and summarizes post-discharge monitoring
Caution and Warning Levels.
Both phases of monitoring evaluate six categories of wastewater constituents: nutrients,
organic material, toxic contaminants, pathogens, solids, and floatables. These six parame-
ters were evaluated as they apply to four different environmental measurement areas: efflu-
ent, water column, benthic environment, and fish and shellfish.
Wastewater Effluent Monitoring
‘Trigger parameters, thresholds, and 1995 monitoring results for the effluent monitoring pro-
gram are summarized on Table ES-1.
The baseline effluent program monitors for nutrients, organic material, toxic contaminants,
pathogens, solids, and oil and grease. Effluent monitoring has demonstrated that improve-
ments made to the MWRA system during the last few years have generally resulted in
improvements in wastewater effluent quality. Pilot treatment plant results indicate that sec-
ondary treatment will significantly reduce the effluent levels of organic material, suspended
solids, and many toxic parameters. As secondary treatment is implemented and toxic
source control measures continue, effluent quality will continue to improve and will result
in compliance with federal secondary treatment standards and Massachusetts water quality
standards.
If The MWRA’s Baseline Outfall
Monitoring Program has gath-
ered considerable information
documenting the existing condi-
tions in Boston Harbor,
Massachusetts Bay, and Cape
Cod Bay. Scientific data collected
during the last few years reflect
current levels of sewage treat-
ment, As improvements are
made to the MWRA sewage treat-
ment process, the extensive eco-
nomic, aesthetic, and ecological
resources of this unique marine
system are expected to benefit.
Mf Wastewater effluent from the
treatment plant is routinely eval-
uated to ensure that discharged
effluent meets required stan-
dards. Also, the future effective-
ness of the secondary treatment
plant is being determined
through operation of a pilot
treatment plant and analysis of
pilot plant effluent.
ii/ OUTFALL MONITORING REPORT: 1995 - MWRA
TABLE ES-1
Effluent Thresholds Compared to 1995 Monitoring Results
Parameter Caution Level Warning Level 1995 Results
Total Nitrogen Total nitrogen annual Total nitrogen annual loading > 14,000 Not exceeded. Annual loading = 11,460 metric
{nutrients) loading > 12,500 mtons/year | mtons/year. tons
cBOD None. Weekly or monthly permit levels. Always exceeded. Minimum value
(organic material) Expected levels: 40 mg/L weekly, during year = 50 mg/L. Pilot secondary treatment
30 mg/L monthly. monthly average = 11 mg/L
Toxics None. Toxics concentrations above permit Monthly average total PCB concentrations:
(toxic contaminants) levels (yet to be determined). 7-225 ng/L. (Mitchell et al. (1997) indicate that the
range is 1-155ng/L.) None of the effluent concen-
trations exceed the most stringent WQC modified
by their respective dilution factors. Pilot treatment
plant concentrations were even lower.
Toxicity None. Acute: effluent LCSO for shrimp <50% Acute: 7 of 12 tests violated shrimp 20% NOEC
(toxic contaminants) effluent. Chronic: effluent NOEC for fish | limit.
growth and sea urchin fertilization Chronic: no violations of minnow 10% NOEC limit;
<1.5% effluent. All tests failed red algae 10% NOEC limit.
Bacteria None. Daily or monthly permit levels. 7 daily exceedances.
(pathogens) Expected levels: 400 fecal col- No monthly exceedances.
iforms/100mL daily, and 200 fecal col-
iforms/100mL monthly.
Suspended None. Weekly or monthly permit levels. Exceeded frequently. Daily range: 23-201 mg/L.
Solids Expected levels: 45 mg/L weekly, Pilot secondary treatment monthly
30 mg/L monthly. average = 12 mg/L.
Floatables None. Floatables less than 5 gal/day. Not measured until secondary treatment
plant is on line.
Oil and Grease None. Oil and grease permit requirements. No exceedances.
(floatables) Expected level: 15 mg/L weekly.
Plant Performance More than 5 violations of Operating in violation of the permit 20 violations, Most from parameters that will be
permit requirements per Tequirements more than 5% of the time improved by secondary treatment.
year. over a year.
The reader is directed to the glossary and acronym summary at the end of the report.
MWRA : OUTFALL MONITORING REPORT: 1995 / ili
Water Column Monitoring Program
Trigger parameters, thresholds, and 1995 monitoring results for the water column program
are summarized on Table ES-2.
A number of different parameters are evaluated in the baseline water column monitoring
program. Studies are underway to gather baseline information on nutrient levels, temper-
ature, salinity, algae, and dissolved oxygen in the marine system. As with other water
bodies, the Massachusetts and Cape Cod Bays system follows an expected regular season-
al pattern but with considerable spatial and temporal variability of complicated interrelat-
ed processes. Starting with the cold well-mixed nutrient-rich waters of winter, the bright-
ening sun of spring provides the light needed for algae (phytoplankton) to grow. Their
abundant growth forms a spring algae bloom which begins to deplete the nutrients, espe-
cially nitrogen. Spring also brings stratification of the water column due to increased
sunshine and freshwater runoff that result in warmer and slightly fresher surface waters.
The spring bloom ends as algae deplete the nutrients in surface waters and are blocked
from nutrient-rich bottom waters by stratification. During summer, the algal biomass is
less overall with the highest biomass located at the boundary between surface and bot-
tom waters (thermocline) where there is a balance between the algal requirement for both
light and nutrients. This continues until the fall, when stratification begins to weaken,
and storms are able to mix the water column, bringing nutrients to surface waters and
resulting in a fall algal bloom.
Monitoring results showed that 1995 was similar to other years with some notable differ-
ences. The 1995 annual average phytoplankton density was the lowest yet observed. The
spring bloom was normal in magnitude but was followed by intense zooplankton grazing
that cleared the water of algae. In the summer, algae were very sparse, although two partial-
mixing events occurred that briefly stimulated intense algal growth. Such partial-mixing
events are not unique to 1995 but MWRA’s methods for observing them have improved.
The fall bloom was large, exceeded only by that in 1993. The dissolved oxygen in bottom
waters in 1995 declined over the summer and was approaching the low values measured in
1994, but earlier fall mixing resulted in ventilation of bottom waters earlier than in 1994.
The minimum dissolved oxygen concentration in 1995 was higher than in 1994, but lower
than in 1992 and 1993. Dissolved oxygen concentrations were slightly above the water
quality standard, but saturations were slightly below the standard. A total of 19 fin, minke,
and unidentified whales were sighted during the summer near field surveys.
Benthic Studies
Trigger parameters, thresholds, and 1995 monitoring results for the benthic program are
summarized on Table ES-3.
The ongoing baseline benthic monitoring program has provided valuable information on the
current status of the benthic environment in the system. Studies are underway to evaluate
benthic ecological communities and sediment quality. In the past few years, there has been
an increase in Boston Harbor of the abundance of a pollution sensitive amphipod, likely
related to sediment quality improvement. Increased amphipod colonization, in turn,
appears to be increasing the rate of sediment quality improvement.
@ The Water Column monitoring
program is designed to measure
water quality in Massachusetts
and Cape Cod Bays, Based on
extensive predictive modeling
studies, changes in water quality
due to outfall relocation are
expected to be minimal in
Massachusetts and Cape Cod
Bays. Detectable changes in
water quality are expected to
occur only in the immediate
vicinity of the outfall. The water
column monitoring program pro-
vides a basis for detecting
changes in water quality and
plankton resulting from the relo-
cation of the effluent outfall. It
also provides a basis for moni-
toring potential food chain
effects on endangered species,
such as humpback and right
whales.
@ Benthic Studies are designed
to evaluate the sea floor
environment in Boston Harbor
and Massachusetts and Cape
Cod Bays. These studies are
designed to assess potential
impacts to the Massachusetts
and Cape Cod Bays sea floor
resulting from relocation of the
outfall. Benthic studies also
provide a means to document
recovery of Boston Harbor
following improvements
to the MWRA system.
iv / OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
Parameter
TABLE ES-2
Water Column Thresholds Compared to 1995 Monitoring Results
Caution Level
Warning Level
1995 Results
Dissolved oxygen
concentration in
Nearfield region
bottom waters
Monthly mean DO is less than 6.5 ppm or 80% of
saturation levels for any one month during stratifica-
tion (June-Oct.)
Monthly mean DO is less than 6 ppm
or 75% of saturation levels for any one
month during stratification (June-Oct.}
DO saturation below warn-
ing level in September
(74.3%).
(See Table 3-2)
Dissolved oxygen
concentration in
Monthly mean DO is less than 6.5 ppm or 80% of
saturation levels for any one month during stratifica-
Monthly mean DO is less than 6 ppm
or 75% of saturation levels for any one
DO saturation below warn-
ing level in October
Stellwagen Basin | tion (June-Oct.) month during stratification (June-Oct,) (71.0%).
bottom waters (See Table 3-2)
Dissolved oxygen | DO depletion rate is greater than 1.5 times the DO depletion rate is greater than 2 1992-95 Average Baseline
depletion rate in
baseline rate for any one month during stratification
times the baseline rate for any one
Rate:
Nearfield region | (June-Oct.), -0.041 mg/L/day. month during stratification (June-Oct.), } -0.027 mg/Liday
bottom waters -0.054 mg/Liday.
1995 Rate:
-0.027 mg/day
Chlorophyll in Annual mean concentration greater than 1.5 times Annual mean concentration greater 1992-95 Baseline:
Nearfield region the baseline annual mean, 2.93 jig/L. than 2 times the baseline annual 1.95 pg/L
mean, 3.90 pg/L. 1995: 1.39 pg/L
Chlorophyll in Season mean concentration exceeds 95th percentile | None. Spring: 1.02 mug/L
Nearfield region | of the baseline seasonal distribution. Summer: 0.73 pg/L
Spring: 2.38 pg/L Fall: 2.58 kg/L
Summer: 2.37 pg/L
Fall: 4.56 ug/L
Nuisance algae in | Alexandrium tamarense None. Alexandrium tamarense
Nearfield region Season mean population densities exceed 95th per- Spring: 0 cells/L
centile of the baseline seasonal mean. Summer: 0 cells/L
Spring: 4.56 cells/L Fall: 0 cells/L
Summer: 1100 cells/L (See Table 3-3)
Fall: 8.67 cells/L
PSP extent in New occurrence. PSP has never been observed None. No occurrences.
Farfield region at 3 of the 18 monitoring stations (see Table 3-4).
Zooplankton Nearfield assemblage shifts from a transitional None. Transitional assemblage in
assemblage in
Nearfield region
community towards an inshore community.
Inshore: Acartia, Eurytemora, Centropages hamatus
Offshore: Calanus, Pseudcalanus, Centropages typi-
cus, Oithona
Nearfield: Transitional between two regions.
nearfield region.
Initial effluent dilu-
tion at new outfall
location
None.
Effluent dilution less than that set in
the NPDES permit.
No data until outfall is
online.
MWRA : OUTFALL MONITORING OVERVIEW REPORT: 1995 /v
TABLE ES-3
Benthic Thresholds Compared to 1995 Monitoring Results
outfall nearfield area.
90% of EPA sediment criteria,
NOAA Effects Range Median (ER-M) value.
Examples: NOAA ER-M values:
PCBs = 180 ng/g
Mercury = 0.71 g/g
Parameter Caution Level Warning Level 1995 Results
Community Structure | Species diversity, composition, None. Shannon-Wiener Diversity Index
(Diversity, Species and relative abundance patterns Midfield mean = 2.71
Composition, and measured in the midfield appre- (Range 2.18 - 3.13)
Species Abundance) | ciably depart from those mea-
in outfall midfield area | sured during the baseline moni- (See also Table 4-2)
toring period, after factoring out
the effect of storms on sediment
texture. Specific diversity thresh-
old values are being developed.
Depth of Oxygenated | RPD depth declines by half. None. Nearfield mean = 3.5 cm
Sediments [Redox The threshold value is under (Range 1.8 - >6.2 cm)
Potential development.
Discontinuity (RPD)
Depth] in outfall
nearfield area.
Toxic Contaminant Nearfield mean toxic contami- Nearfield mean toxic contaminant concentra- Example Results:
Concentrations in nant concentrations greater than | tions greater than EPA sediment criteria or the PCBs:
Geometric Mean = 4 ng/g
Range = 1.1 - 53 ng/g
Mercury:
Geometric mean = 0.16 yo/g
(See also Table 4-3)
In Massachusetts Bay near the site of the future outfall, in an area called the nearfield, the
benthic sedimentary environment, or habitat, is highly diverse, with large variability in sedi-
ment type over relatively short distances. The benthic biological communities also vary spa-
tially, reflecting a strong influence of sediment type on the benthic community characteris-
tics. In addition, the benthic environment in the nearfield is highly changeable, with dra-
matic shifts in both sediment type and benthic organisms occurring after storm events. The
dominant benthic species in 1995 was also abundant in 1987, but not in 1992 through
1994. Benthic organism densities in Massachusetts Bay are moderately high and the com-
munity structure does not reflect stressed conditions. The numbers of species in the benth-
ic community are similar in the nearfield and farfield, but the types of species are different.
Sediment metal and organic concentrations in 1995 were similar to previous values and,
except for elevated mercury consistently found at one very muddy station, were generally
below environmental criteria.
Fish and Shellfish Monitoring Program
Trigger parameters, thresholds, and 1995 monitoring results for fish and shellfish are sum-
marized on Table ES-4.
The baseline fish and shellfish monitoring program focuses on flounder, lobster, and mus-
sels. In 1995, as in previous years, the contaminant concentrations in fish and shellfish at
all sites have consistently been well below levels that might cause any concern because of
human consumption. Nevertheless, the pattern of contamination provides evidence of the
I The Fish and Shellfish monitor-
ing program focuses on key nat-
ural resources in the marine
environment. This program eval-
uates potential risks to human
health and the environment from
contamination in fish and shell-
fish. Fish and shellfish studies
provide a basis for evaluating
recovery of natural systems fol-
lowing MWRA upgrades.
vi/ OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
TABLE ES-4
Fish and Shellfish Thresholds Compared to 1995 Monitoring Results
Parameter Caution Level Warning Level 1995 Results
Mercury in fish Annual mean mercury concentration in flounder, lob- | Annual mean mercury concentration in | Flounder - 0.06 jig/g
and shellfish ster, and caged mussel meat greater than 0.5 g/g | flounder, lobster, and caged mussel Lobster - 0.13 ug/g
from Outfall site | wet weight (50% of the US FDA action level). tissue is greater than 0.8 w.g/g wet Mussel - NA‘
weight (80% of the US FDA action
level).
PCBs in fish and | Annual mean PCB concentration in flounder, lobster, | Annual mean PCB concentration in Flounder - 0.041 jg/g
shellfish from and caged mussel meat greater than 1 jig/g wet flounder, lobster, and caged mussel Lobster - 0.015 j1g/g
Outfall site weight (50% of the US FDA action level). tissue is greater than 1.6 jig/g wet Mussel - NA
weight (80% of the US FDA action
level).
Lead in mussels] Annual mean lead concentration in caged mussel Annual mean lead concentration in Mussel - NA
at Outfall site meat greater than 2 1g/g wet weight. caged mussel tissue is greater than
3 .9/g wet weight.
Lipid-normalized | Lipid-normalized toxic concentrations in flounder, None. Concentrations in wg
toxics in fish and | lobster and caged mussel meat greater than two toxic per gm lipid
shellfish from times the baseline concentrations. Lobster PCBs: 2.9
Outfall site Lobster DDT: 0.4
Flounder PCBs: 11.1
Flounder DDT: 1.1
Liver disease Flounder liver disease (CHV) incidence greater None. Flounder CHV prevalence:
incidence in fish | than in Boston Harbor. The 1991-95 average is 14%
from Outfall site 48%.
' Outfall site musse! cage arrays were lost in 1995.
degree of exposure to the fish. In general, contaminant concentrations in flounder meat
decline progressively from Boston Harbor to the future outfall site to Cape Cod Bay.
However, the highest 1995 concentrations of several metals in flounder liver were present in
flounder from the future outfall site. The 1995 data indicated significantly increased con-
centrations of DDT and PCBs in flounder liver over values from previous years. Liver
lesions have been present in flounder from all sites, and the decline started in 1992 contin-
ues in the 1995 results.
Contaminant concentrations in lobster meat generally followed the same spatial pattern as
contaminants in flounder meat. In lobster hepatopancreas, the highest organic contaminant
concentrations in 1995 were present at the future outfall site. Metal concentrations in lob-
ster hepatopancreas were lower in Cape Cod Bay than other sampling sites.
Hepatopancreas metal concentrations were similar at the other sites, except for mercury
which was highest at the future outfall site. All levels are below those of concern, and are
expected to improve as secondary treatment leads to improved effluent and water quality in
Boston Harbor and the Bays.
MWRA : OUTFALL MONITORING OVERVIEW REPORT: 1995 / O01
1.0 INTRODUCTION
1.1 Report Objectives and Content
The Outfall Monitoring Program is an important component of the Massachusetts Water
Resources Authority's (MWRA’s) overall program to improve the quality of Boston Harbor.
The Outfall Monitoring Program provides the means to identify, measure and respond to
any impacts associated with the relocated outfall. The Contingency Plan (MWRA, 1997)
outlines the MWRA's response program in case any unexpected impacts occur. The Outfall
Monitoring Overview Report is intended to serve as an annual companion document to the
Contingency Plan.
The objective of the Outfall Monitoring Overview Report is to describe the monitoring
program results on an annual basis and compare those results to established environmental
benchmarks or threshold levels for trigger parameters (described below). If monitoring data
indicate that changes to thresholds or trigger parameters are necessary, the report recom-
mends appropriate modifications. In addition, the report will summarize any actions taken
pursuant to the Contingency Plan during the year.
This report presents monitoring program results and threshold comparisons for field data
collected through 1995. Since data collection started in 1992 and the future outfall is not
yet operational, the data in this report represent the fourth year of the baseline collection
period. As such, comparisons of data to thresholds are used to test the validity of the
threshold values. Also, the report provides interim threshold values for those parameters
for which thresholds will be determined from a full set of baseline data. Finally, since the
outfall is not operational, actions pursuant to the Contingency Plan are not addressed in this
1995 report, but will be in future reports.
This report is organized into the following sections: (1) this introduction that discusses the
overall background and components of the monitoring program; (2) four sections that dis-
cuss the issues, design, comparison to thresholds, and recent results for each area of the
monitoring program: Effluent, Water Column, Benthic Studies, and Fish and Shellfish; and
(3) a glossary and summary of acronyms.
1.2 Background
In 1986 the MWRA initiated a program to end longstanding violations of the Clean Water
Act associated with the discharge of sewage sludge and effluent in Boston Harbor. This
program includes the relocation of the treated effluent discharge point to a location in
Massachusetts Bays (Figure 1-1) approximately 9.5 miles from the present Deer Island
outfall. Discharge of effluent through the new outfall is expected to begin in 1998.
The U.S. Environmental Protection Agency (EPA) and the National Marine Fisheries
Service (NMFS) assessed the potential impacts associated with the discharge of MWRA's
wastewater effluent into Massachusetts Bay. Both the EPA and NMFS determined that there
would not be significant water quality or biological impacts associated with the project.
This conclusion was documented in the EPA’s Supplemental Environmental Impact
Statement (SEIS) and Biological Assessment and the NMFS's Biological Opinion.
i A number of related reports
have been produced by MWRA.
The Effluent Outfall Monitoring
Plan, Phase I: Baseline Studies
(November 1991) and Phase Ii:
Post Discharge Monitoring
(draft November 1995) describe
the goals, strategy, and design of
the Outfall Monitoring Program
in detail. The Contingency Plan
(February 1997) provides a
detailed discussion of the devel-
opment of trigger parameter
values and MWRA’s planned
contingency measures. The
State of Boston Harbor reports
focus on the Boston Harbor
system, rather than on
Massachusetts and Cape Cod
Bays.
02 / OUTFALL MONITORING REPORT: 1995 : MWRA
II The material presented in this
report represents data collected
through the 1995 field season,
and therefore reflects the
current and recent levels of
sewage treatment. These data
are synthesized in a series of
technical reports prepared at
least annually for every project
area. Synthesis reports for
1996 data are currently in
development and are expected to
add to the understanding of the
Harbor and Bay system. A cur-
rent listing of the technical
reports can be found on the
internet at
http://www.mwra.com.
FIGURE 1-1
Distances of the new outfall
from selected sensitive areas
in Massachusetts and
Cape Cod Bays. The existing
outfalls are near Deer Island
and the more southerly Nut
Island. The new outfall is 9.5
miles from Deer Island.
Even though minimal impacts were predicted from the relocated, cleaner discharge,
concerns remained with respect to the potential environmental effects associated with the
relocation of the wastewater discharge to Massachusetts Bay. General concerns identified
with respect to the relocated discharge are potential aquatic life, human health, and aesthet-
ic impacts in Massachusetts and Cape Cod Bays.
In order to assure that discharge from the new outfall does not result in adverse impacts to
human health or the environment, the EPA and the Massachusetts Executive Office of
Environmental Affairs (EOEA) required the development of an outfall monitoring program.
The objective of the monitoring program was to establish baseline conditions of the
Massachusetts and Cape Cod Bays ecosystem and measure any future impacts on the sys-
tem due to outfall relocation. At the direction of the EOEA, an Outfall Monitoring Task
Force (OMTF) was formed to provide MWRA with guidance and recommendations on the
development of a monitoring plan. The OMTF is composed of academic scientists, as well
as representatives from federal and state regulatory agencies and citizens’ groups.
Numerous scientific studies performed as part of the outfall siting process in 1986 and 1987
were used as the basis by MWRA and the OMTF for the development of the initial Outfall
Monitoring Plan in 199]. Baseline studies, dedicated to determining background conditions
in the Bays, began in 1992 (except for flounder studies which began in 1991) and will con-
tinue until the new outfall becomes operational in 1998. Then, similar post-discharge stud-
ies, dedicated to determining the effects of the discharge, will begin.
The OMTF and MWRA review the monitoring results on an ongoing basis and work to
T
T Tt
— 427308
X New Outfall
X Existing Outfalls
| aaeis?
—| 42°00"
Cape Cod
Bay
auras",
71°00" 0°45" 70°30" 70°15" 70°00"
MWRA - OUTFALL MONITORING REPORT: 1995 / 08
implement cost-effective modifications that better address public and technical concerns.
In May 1996, a technical workshop with MWRA scientists, OMTF members, and nationally
recognized scientists was held to evaluate the outfall monitoring program. The workshop
included a review of monitoring methods and results, trigger parameters and threshold val-
ues, and an evaluation of changes that would improve the effectiveness of the program.
Mi MWRA uses two levels of thresh-
old values to evaluate the need
for action under the Contingency
Plan:
mw Caution Level exceedances
indicate the need for increased
study or attention.
mw Warning Level exceedances
indicate the need for action to
avoid potential environmental
impact, triggering the develop-
ment and implementation of a
response plan.
1.3 Trigger Parameters and Thresholds
The Outfall Monitoring Program provides the basis for evaluating potential impacts associat-
ed with the relocated outfall and the need for action under the Contingency Plan. MWRA
evaluates monitoring program results based on specific measurement indicators of changes
from benchmark environmental conditions. These measurement indicators were designated
as trigger parameters in the Contingency Plan. A summary of the current trigger parameters
is presented in Table 1-1. Each trigger parameter has a quantitative, or in some cases a
qualitative, threshold that indicates the potential for impacts. Once discharge begins, the
exceedance of trigger parameter threshold values will automatically trigger MWRA action.
There are two types of thresholds under development that will be used to alert MWRA to
different degrees of potential environmental risk. Caution Level
exceedances would indicate the need for more intensive study or
increased attention. Warning Level exceedances would indicate the
need for a response to avoid a potential environmental impact.
The trigger parameters and thresholds for each of the measurement
areas are discussed in detail in the corresponding report section
TABLE 1-1
Summary of Trigger Parameters
Monitoring Trigger
Area Parameter
below.
Effluent Total Suspended Solids
The definition of a threshold exceedance depends on the trigger Biochemical Oxygen Demand
parameter. It is desirable for most of the measured parameters (e.g. Pathogenic Indicator Bacteria
contaminant concentrations, treatment plant violations, algae and Nitrogen Loading
liver disease) to remain below the threshold. Other parameters (e.g. Toxic Metals and Organic Chemicats
dissolved oxygen level, dilution, dissolved oxygen penetration into Toxicity Testing
sediments, percent effluent with specified toxicity level, and diversi- Floatables
ty) should remain above the threshold. Oil and Grease
Plant Compliance with Permit Limits
MWRA has used the following sources to establish threshold val- Water Column Dissolved Oxygen Concentration
ues for the trigger parameters: Dissolved Oxygen Respiration Rate
m_ Limits expected in the forthcoming EPA/MADEP NPDES Chlorophyll
permit Nuisance and Noxious Algae
m= State water quality standards Zooplankton
Predictions made about the impacts of the discharge dur- Diffuser Mixing
ing the preparation of the EPA's SEIS Benthos Benthic Community Structure
m Expert guidance and opinion Sediment Oxygen _
Expert guidance has helped MWRA refine the definition of the oer Metal and Organic
threshold values. The technical workshops held in May 1996 made Fish and Shelfish | Mercury and PCBs in Flounder, Lobster,
the recommendation that MWRA should revise the proposed and Mussels
Caution and Warning Levels. Specifically, it was recommended Lead in Mussels
that MWRA focus on a reduced set of critical trigger parameters, Lipophilic Toxic Contaminants
define the trigger parameters more precisely, allow for seasonality Liver Disease in Flounder
04/ OUTFALL MONITORING REPORT: 1995 - MWRA
Mi Environmental data generally
demonstrate considerable vari-
ability in both space and time
due to the inherent behavior of
natural systems. In order to
accurately measure the charac-
teristics and variability of natur-
al systems, environmental moni-
toring programs are typically
designed to collect large
amounts of data. Designs of
sampling programs, such as the
MWRA Outfall Monitoring
Program, consider the appropri-
ate spatial and temporal scales
by including a sufficient number
of monitoring stations to allow a
description of spatial data vari-
ability, as well as a sufficient
number of sampling times or
events to describe the temporal
variability.
of the natural baseline in the definition of thresholds, and choose threshold levels which are
more protective of the environment. In addition, in the case where the NPDES permit lim-
its serve to define the Warning Levels, MWRA decided that it would not be useful to try to
define a corresponding Caution Level. This report, the 1995 Outfall Monitoring Overview
Report, reflects the changes resulting from those recommendations and decisions.
Several of the trigger parameters are expressed as change relative to baseline values.
Because the baseline period is ongoing, interim thresholds are calculated as an exercise in
this report based on the existing four years of monitoring data. The thresholds will be
updated each year until just before the outfall begins discharging, when the final threshold
values will be calculated.
1.4 Monitoring Program Summary
The Outfall Monitoring Program was developed and has evolved with continuous atten-
tion to a number of specific goals and objectives. The Outfall Monitoring Program is
intended to:
m Develop baseline data from which future changes can be evaluated
m Test whether the impact of the discharge is within the bounds predicted in the
SEIS;
= Evaluate compliance with threshold values for trigger parameters (as defined
below); and
= Measure and evaluate potential impacts to Massachusetts and Cape Cod Bays
associated with outfall relocation.
The monitoring program has focused on the following six wastewater constituents for deter-
mining the environmental impact of coastal discharges of treated sewage, as recommended
by the National Research Council:
m= Nutrients
Organic Material
Toxic Contaminants
Pathogens
Suspended solids
Floatables
The Outfall Monitoring Program was designed to obtain data that would allow an
assessment of the water quality and ecological impacts of these constituents. Twenty
key measurement parameters were defined within the context of four different environ-
mental monitoring areas: effluent, water column, benthic environment, and fish and
shellfish. A summary of the monitoring program is presented in Table 1-2.
MWRA + OUTFALL MONITORING REPORT: 1995 / 05
Effluent Sampling
Objective
Characterize wastewater
discharged from Deer Island
Treatment Plant and pilot
secondary treatment plant
TABLE 1-2
Summary of MWRA Monitoring Program
Monthly
Daily
Monthly
3 Times/Day
Daily
Weekly
Weekly
WATER COLUMN MONITORING
Sampling Locations and Schedule
EFFLUENT MONITORING
nalyses
« Nutrients
* Organic material (cBOD)
* Toxic contaminants
* Pathogens
* Solids
* Oil & Grease
* Floatables (starting in 1998)
Nutrient Flux Surveys
on a regional scale
through satellite imagery
Evaluate nutrient interactions
between the sediment
and water column
Nearfield Surveys Collect water quality data * 17 surveys/year * Temperature * Nutrients
near future outfall location * 21 locations (See Figure 3-1) * Salinity * Solids
* Dissolved oxygen * Chlorophyll
* Plankton « Water clarity
* Marine mammal/ « Photosynthesis
sea turtle * Respiration
observations
Farfield Surveys Collect water quality data * 6 surveys/year Same as Nearfield Surveys except no
throughout Massachusetts * 26 locations (See Figure 3-1) mammaliturtle observations
and Cape Cod Bays
Plume Track Surveys | Track location and * 3-4 surveys/year beginning in 1999 * Salinity
characteristics of (An exploratory survey was performed * Temperature
discharge plume in 1995). « Dissolved oxygen
* Chlorophyll
* Solids
Mooring Provides continuous * Continuous monitoring * Temperature * Chlorophyll
oceanographic data * Single station * Salinity
near outfall * 3 depths © Water clarity
Remote Sensing Evaluate outfall impacts * Available daily (cloud cover permitting) * Surface Temperature
BENTHIC MONITORING
* 5 surveys/year
* 8 locations (See Figure 4-1)
* Chlorophyll (not available in 1995)
* Oxygen demand
© Nutrient flux
* Porewater nutrients
Soft Bottom Surveys
Evaluate sediment quality
in Boston Harbor
and Massachusetts Bay
* 60 Boston Harbor stations
(See Figure 4-2)
* 20 nearfield stations (See Figure 4-3)
* 11 farfield stations (See Figure 4-4)
* Sediment chemistry
¢ Benthic community composition
« Sediment profile imaging
Hard Bottom Surveys
Characterize marine
communities in rock
and cobble areas
* 1 survey/year
* 6 transects (See Figure 4-5)
SH AND SHELLFISH MONITORING
* Topography
* Substrate
* Benthic community composition
condition and short-term
contaminant bioaccumulation
Flounder Studies Determine contaminant * 1 survey/year * Tissue contaminant concentrations
body burden and « 5 locations (See Figure 5-1) * Physical abnormalities
population health {including histopathology)
Lobster Studies Determine contaminant * d survey/year * Tissue contaminant concentrations
body burden * 3 locations (See Figure 5-1) * Physical abnormalities
Mussel Studies Evaluate biological © 1 survey/year * Tissue contaminant concentrations
* 3 locations (See Figure 5-1)
* Physical abnormalities
06 / OUTFALL MONITORING REPORT: 1995 - MWRA
i For the goals of the program
to be met, all of the data must
be of known, high quality. Data
quality is maintained through
the program-wide use of rigor-
ous Quality Assurance/Quality
Control procedures. Data from
field surveys and laboratory
analyses are exhaustively
checked and validated to ensure
that field equipment was work-
ing properly during surveys
and that the analyses met the
program's Quality Control objec-
tives. Only validated data are
loaded onto the centralized
database.
The monitoring program is designed to provide data with sufficient temporal and spatial
detail to characterize the variability of the Massachusetts and Cape Cod Bays system. Each
of the different program areas has different requirements in this regard and the monitoring
program design reflects these differences. For example, the water column in Massachusetts
and Cape Cod Bays experiences considerable temporal variability and spatial patchiness.
The combination of frequent boat-based surveys, continuous monitoring at a mooring, and
satellite imagery in the water column program are designed to resolve this variability and
provide detailed characterization of the water column system. The benthic environment
displays at least as much spatial patchiness as the water column but much less temporal
variability. Correspondingly, benthic monitoring is much less frequent than water column
monitoring but provides spatial coverage that is similar.
15 Data Management
Since the beginning of the Outfall Monitoring Program in 1992, more than 200 million
pieces of data have been generated and compiled. As the program continues, the amount
of compiled data will grow even larger. In order to meaningfully use this large mass of
data, a coupled computerized database system and Geographical Information System (GIS)
has been developed. The coupled database/GIS system allows MWRA to store, retrieve,
analyze, and display data from the monitoring program. Arc/Info is used as the GIS plat-
form. The database management system consists of an Oracle 7 server networked to PC
workstations running MS Access. This system allows monitoring data to be entered, ana-
lyzed, and viewed simultaneously by several researchers working at their own computers.
The database is the source of the multi-year data analyzed by researchers in the preparation
of synthesis reports.
MWRA « OUTFALL MONITORING REPORT: 1995 / 07
2.0 Effluent Monitoring Program
2.1 Effluent Issues
The National Research Council (1993) has recommended consideration of the following six
wastewater constituents in determining the environmental impact of coastal discharges of
treated sewage:
m = =Nutrients
Organic Material
Toxic Contaminants
Pathogens
Solids
Floatables
The issues associated with each of these constituents are described below.
Nutrients
Nutrients are essential for the growth of algae and other aquatic plants. However, excessive
concentrations of nutrients in the water can be detrimental, and may lead to low dissolved
oxygen levels and eutrophication. For marine and coastal environments, such as the
Massachusetts and Cape Cod Bays system, nitrogen is the most important nutrient and is
the focus of effluent monitoring. However, measurements are made regularly of phospho-
rous and occasionally silica.
Organic Material
Organic material is a concern because as it decays it consumes dissolved oxygen (DO),
which is critical to aquatic life. Low levels of DO may have serious effects on fish and
other marine animals. The amount of DO consumed by decomposing organic material
in effluent is the biochemical oxygen demand (BOD) which consists of the nitrogenous
biochemical demand (nBOD) plus carbonaceous biochemical oxygen demand (cBOD).
The standard measurement for BOD is the 5-day BOD test, or BOD5. The BOD5 mainly
measures the carbonaceous BOD.
Toxic Contaminants
Toxic contaminants are substances that can cause diseases such as cancer through direct
contact with or accumulation in living tissue. Toxic contaminants include trace metals
(such as lead, mercury, chromium, and cadmium); volatile organic compounds (such as
benzene, toluene, and chlorinated solvents); semi-volatile organic compounds (including
polychlorinated biphenyls [PCBs], polyaromatic hydrocarbons [PAHs], and pesticides such
as DDT); ammonia; and chlorine. To evaluate levels of trace metals and organic contami-
nants in the effluent, the MWRA collects and analyzes samples from the effluent from
MWRA&'’s treatment plant. In addition, bioassay tests, which measure the response of indi-
cator species to treated effluent, are being used to evaluate toxicity to various life stages of
marine organisms such as shrimp, finfish, red macroalgae, and sea urchins.
ll Bioassays measure the response
of indicator species such as
shrimp to toxics in the effluent
under specified laboratory condi-
tions, Bioassays designed to
assess acute toxicity are
expressed in measurement units
known as "LC80s." An LC50 is
the concentration at which 50%
of a shrimp population survives.
For example, an LC80 of 60
means that half of the shrimp
survived a mixture that was
60% effluent and 40% dilution
water. To assess chronic toxict-
ty, the MWRA measures the efflu-
ent's "No Observed Effects
Concentration (NOEC)." The
NOKC is the highest concentra
tion of effluent at which there is
no statistical difference in test
organism response when com-
pared against a control with no
effluent.
08 / OUTFALL MONITORING REPORT: 1995 - MWRA
Pathogens
Human pathogens are bacteria, viruses, and protozoa from human and animal waste that
cause disease in humans. Although human pathogens are not known to harm marine life,
they may concentrate in filter feeding shellfish, such as mussels and clams. Human expo-
sure to pathogens may occur primarily from the consumption of contaminated shellfish and
from incidental ingestion of water while swimming. Fecal coliform bacteria are often used
as an indicator of the presence of human pathogens and to evaluate the effectiveness of
chlorine addition at the treatment plant. MWRA regularly measures the levels of fecal and
total coliform bacteria. Any health effect of pathogens which escape chlorination and are
discharged in marine waters would not extend far from the outfall due to dilution and nat-
ural death of the microorganisms.
Suspended Solids
Suspended solids are small particles of matter, such as mud, sand, or organic debris, sus-
pended in the water column. Solids influence the behavior of toxic contaminants and other
water quality parameters but the primary concern associated with solids is deposition and
the resulting potential for smothering of the bottom habitat and benthic (bottom dwelling)
organisms. Another issue of some concern is the aesthetic effect of loss of clarity of waters
with high suspended solids levels.
Floatables
Floatables are pollutants that sit on the water surface, as opposed to being in the water col-
umn or on the bottom. Typical floatables are plastic tampon applicators, oil, and grease.
Floatables are primarily an aesthetic problem, although some floatables, such as oil, can be
harmful to marine life.
2.2 Monitoring Program Design
The primary objective of the effluent monitoring program is to characterize waters dis-
charged from the Deer Island treatment plant. Concentrations and variability of chemical
and biological constituents in the treatment plant effluent are measured. These data will
allow comparison to NPDES permit limitations and evaluation of loadings and potential
impacts on Massachusetts Bay.
Under the NPDES program the samples of the Deer Island treatment plant effluent were col-
lected and analyzed as outlined below. Composite samples are taken over a 24-hour period
usually at weekly intervals (“weekly composite”). Compositing provides the best estimate
of the average concentration of contaminants provided that they do not degrade in the stor-
age unit; those that would degrade have to be collected as a grab sample.
The following samples are collected under the NPDES program:
m = Nutrients. A weekly composite sample is analyzed for total Kjeldahl nitrogen,
ammonia, nitrate, nitrite, total phosphorus, and phosphate.
m= Organic material. A daily composite sample is analyzed for 5-day Biochemical
Oxygen Demand.
m= Toxic contaminants. A weekly composite sample is analyzed for trace metals of
concern: silver, cadmium, copper, chromium, mercury, lead, molybdenum, nickel,
and zinc. The analyses incidentally yield data on arsenic, selenium, thallium,
MWRA + OUTFALL MONITORING REPORT: 1995 / 09
boron, beryllium, iron, and antimony, but these are of little concern for this out-
fall. Three composite samples per month are analyzed for organic contaminants:
petroleum hydrocarbons, pesticides, PAH, PCB, phenols, and phthalates. Volatile
organic compounds (VOA) are analyzed in three grab samples per month. Three
daily composite samples are used in the monthly bioassay toxicity tests,
m Pathogens. Three grab samples per day are analyzed for fecal and total coliform.
m Suspended solids. A daily composite sample is analyzed for total suspended
solids.
m = Floatables. A weekly grab sample is analyzed for oil and grease. Once a week
the amount of floating material in the final skimmer will be visually estimated to
estimate the efficiency of the upstream skimmers (observations will begin in
1998).
In addition to samples collected and analyzed under the NPDES program, other samples
may be collected occasionally to provide more sensitive and detailed information about the
effluent. Those measurements are called the detailed effluent characterization study
(DECS). In 1995 the DECS measurements were made at Deer Island only; every month two
samples were taken a few days apart.
= Nutrients. Twice-monthly grab samples were analyzed for nitrogen (ammonia,
nitrate, nitrite, particulate organic nitrogen, total dissolved nitrogen, and urea),
phosphorous (P04, particulate organic phosphorous, total dissolved phosphorous),
silicon (dissolved silicate, and biogenic silica), carbon (particulate organic carbon)
and stable isotopes of nitrogen and sulfur.
m = Toxic contaminants, Twice-monthly composite samples were analyzed for trace
metals: silver, cadmium, copper, chromium, mercury, lead, molybdenum, nickel,
and zinc. Organic contaminants are analyzed in twice-monthly composite sam-
ples: 17 persistent chlorinated pesticides, an extended list of PAHs, 20 PCB con-
geners, and C10 to C14 linear alkyl benzenes.
m= Sewage tracer. Twice-monthly composite samples were analyzed for Clostridium
perfringens spores.
m Suspended solids. Twice-monthly grab samples were analyzed for total suspended
solids to normalize other measurements.
In conjunction with the relocation of the outfall, MWRA is upgrading the effluent treatment
process. In order to assess the effects of the new treatment process on effluent quality
before the new treatment facility is operational, MWRA is running a small scale pilot sec-
ondary treatment plant. The second objective of the effluent monitoring program is to eval-
uate the performance of the pilot secondary treatment plant under different operating condi-
tions to explore ways to maximize the removal efficiencies. The effluents from the current
treatment process and the pilot secondary treatment plant are being compared in order to
assess the removal efficiency of the new process. Therefore, many of the parameters mea-
sured in the main effluent treatment plant are also monitored at the pilot secondary treat-
ment plant.
2.6 Threshold Comparison
Thresholds for nine parameters are being established for the effluent. The thresholds for
organic material (BOD), toxic contaminants (toxics and toxicity), pathogens (bacteria),
@ Priority pollutants are sub-
stances that the EPA has deter-
mined to be of national concern
because of their toxicity at cer-
tain concentrations.
W@ Water quality criteria are maxi-
mum pollutant concentration val-
ues, or minimum concentrations
of desirable parameters (such as
DO), that were established to
support a specific water body
use, such as protection of aquatic
life. Acute criterta values were
developed to be protective of rela-
tively short-term (less than 96
hours) exposure to pollutants.
Chronic criteria are values that
provide protection from relative-
ly long-term pollutant exposure.
@ Effluent sampling provides the
MWRA with the ability to moni-
tor several nutrients, trace met-
als, and anthropogenic organic
compounds prior to discharge.
As the level of treatment increas-
es, effluent quality ts expected to
improve substantially.
10 / OUTFALL MONITORING REPORT: 1995 - MWRA
Parameter
Total Nitrogen
TABLE 2-1
Effluent Thresholds Compared to 1995 Monitoring Results
Caution Level
Total nitrogen annual
Warning Level
Total nitrogen annual loading > 14,000
1995 Results
Not exceeded. Annual loading = 11,460 metric
(floatables)
Expected level: 15 mg/L weekly.
(nutrients) loading > 12,500 mtons/year | mtons/year. tons
cBOD None. Weekly or monthly permit levels. Always exceeded. Minimum value
(organic material) Expected levels: 40 mg/L weekly, during year = 50 mg/L. Pilot secondary treatment
30 mg/L monthly. monthly average = 11 mg/L
Toxics None. Toxics concentrations above permit Monthly average total PCB concentrations:
(toxic contaminants) levels (yet to be determined). 7-225 ng/L. (Mitchell et al. (1997) indicate that the
range is 1-155ng/L.) None of the effluent concen-
trations exceed the most stringent WQC modified
by their respective dilution factors. Pilot treatment
plant concentrations were even lower.
Toxicity None. Acute: effluent LC50 for shrimp <50% Acute: 7 of 12 tests violated shrimp 20% NOEC
(toxic contaminants) effluent, ; limit, ; 7
Chronic: effluent NOEC for fish growth Chronic: no violations of minnow 10% NOEC limit;
and sea urchin fertilization <1.5% All tests failed red algae 10% NOEC limit.
effluent.
Bacteria None. Daily or monthly permit tevels. 7 daily exceedances.
(pathogens) Expected levels: 400 fecal col- No monthly exceedances.
iforms/100mL daily, and 200 fecal col-
iforms/100mL monthly.
Suspended None. Weekly or monthly permit levels. Exceeded frequently. Daily range: 23-201 mg/L.
Solids Expected levels: 45 mg/L weekly, Pilot secondary treatment monthly
30 mg/L monthly. average = 12 mg/L.
Floatables None. Floatables less than 5 gal/day. Not measured until secondary treatment
plant is on line.
Oil and Grease None. Oil and grease permit requirements. No exceedances.
Plant Performance
More than 5 violations of
permit requirements per
year.
Operating in violation of the permit
requirements more than 5% of the time
over a year.
20 violations. Most from parameters that will be
improved by secondary treatment.
The reader is directed to the glossary and acronym summary at the end of the report.
solids (TSS), and oil and grease will be based on the NPDES permit to be issued by the EPA
to the MWRA for the Deer Island Treatment Plant and outfall. Three other thresholds, for
nutrients (total nitrogen), floatables (other than oil and grease), and plant performance,
have already been specified. A summary of the expected effluent thresholds and compari-
son of 1995 monitoring results to thresholds are given in Table 2-1.
Most of the threshold levels are expressed as a number in relation to a certain interval of
time and space. For example, the daily bacteria limit is compared to the pooled measure-
ments in a day. There are three measurements of bacteria in a day, and pooling is calculat-
ed in this case as a geometric mean. Likewise, the monthly limit is compared to the pooled
MWRA * OUTFALL MONITORING REPORT: 1995 / 11
measurements taken over a month. The concept of a spatial interval is more relevant to the
other monitoring areas and will be introduced in Section 3.3.
Nutrients
Because nitrogen is the most important nutrient to monitor when discharging effluent to
marine waters, MWRA tests treatment plant effluent for the concentration of total nitrogen.
Assuming certain loadings of nitrogen from the effluent, the SEIS and later modelling stud-
ies predicted little or no impact from the outfall discharges. Caution and Warning Levels
have been set to verify that the loads assumed in those predictions are not exceeded.
Therefore, the Caution and Warning Levels for total nitrogen annual loading have been
established as 12,500 and 14,000 metric tons/year, respectively. In 1995, as in previous
years, the total nitrogen load has been below these levels. The 1995 annual load of total
nitrogen from both Deer Island and Nut Island was estimated at 10,003 metric tons from the
DECS data. The 1995 annual load of total nitrogen from NPDES data is 9163 metric tons
and the difference is due to composite sampling (NPDES) versus grab sampling (DECS).
The pilot secondary treatment plant study showed an average of 10% total nitrogen
removal.
Organic Material
Although the NPDES permit has not been issued, the expected Warning Level thresholds for
effluent organic materials are 40 mg/L on a weekly average, and 30 mg/L on a monthly
average. In 1995, BOD ranged from 50 to 179 mg/L with an average of 102 mg/L. The
thresholds being developed apply to the new secondary treatment system, but the 1995
results are from the primary treatment system and experimental pilot plant. BOD levels are
expected to drop to below the Warning Level when the new system is fully operational. The
monthly average BOD in the effluent of the pilot secondary treatment plant was 11 mg/L,
though the pilot plant in 1995 was tested under varying conditions including those more
extreme than expected during future plant operation. The highest monthly average for 1995
was 19 mg/L.
Toxic Contaminants
NPDES toxic contaminant limits are based on water quality standards and very conservative
assumptions about water conditions within the effluent/sea water mixing zone (i.e. strati-
fied conditions and conservative estimates on available dilution). If limits for toxics are
included in the new NPDES permit, they will serve as the Warning Levels for effluent toxic
contaminant concentrations. If not, the thresholds will be revised to reflect water quality
standards. Presently, the only toxic parameter expected in the permit is PCBs.
In addition to concentration-based tests, the NPDES permit will require the use of
laboratory-based bioassays to assess acute and chronic toxicity. The Warning Level for
acute toxicity is expected to be an effluent LC50 of less than 50% effluent for shrimp. The
Warning Level for chronic toxicity is expected to be effluent NOEC for fish growth and sea
urchin fertilization that is less than 1.5% effluent (derived from an assumed dilution of 68).
The expected permit limits that form the basis for these thresholds differ from the present
toxicity permit limits.
The present acute limit for shrimp of 20% NOEC may change to LC50<50%. The present
chronic limit using sheepshead minnow (10% NOEC) will change to one using the more
sensitive fish Menidia (1.5% NOEC at edge of mixing zone). The present chronic limit
12 / OUTFALL MONITORING REPORT: 1995 : MWRA
using the red alga Champia (10% NOEC) will change to one using a more reliable laborato-
ry test organism, the sea urchin Arbacia (1.5% NOEC at edge of mixing zone). Only the
results for the present acute toxicity test can be easily compared to the future Warning
Levels listed in Table 2-1, and this is reflected in the 1995 results in the table.
Pathogens ;
Because of the dilution that will be achieved at the new outfall, it is nearly inconceivable
that any bacterial water quality standards for fishing, shellfishing, or swimming would be
exceeded (except in the immediate vicinity of the outfall, where the Division of Marine
Fisheries prohibits fishing and shellfishing) if effluent bacteria concentrations were below
the NPDES permit limits.
The Warning Level is based on the expected NPDES permit limits of 400 fecal coliform/100
mL on a daily basis, and 200 fecal coliform/100 mL on a monthly basis. That limit may be
revised, however, to reflect the tradeoffs between chlorine toxicity and health risks. Due to
dilution and death of the pathogens, health risks are low except in the immediate vicinity of
the outfall, where some further degree of protection is provided by the future ban of the
Division of Marine Fisheries on fishing and shellfishing at the future outfall. As this report
was being prepared, the regulatory authorities were discussing whether a less stringent bac-
teria limit (14,000 fecal coliform/100 mL) would be appropriate. This is based on a weekly
threshold of 200 fecal coliform/100 mL and a dilution of 70.
Solids
The expected NPDES permit limits for total suspended solids (TSS) have been used as the
MWRA warning thresholds. These limits are 45 mg/L of TSS weekly, and 30 mg/L of TSS
monthly. In 1995, TSS concentrations averaged 63 mg/L with a range between 23 and 201
mg/L. Although the TSS appears to be lower in the new primary plant effluent than in pre-
vious years, these values are still substantially higher than the established threshold values.
The MWRA anticipates that completion of the new secondary treatment facility will further
improve effluent water quality, and that TSS levels will drop substantially once secondary
treatment commences. The TSS level for the secondary treatment plant is expected to be
approximately 15 mg/L. The pilot secondary treatment plant was tested under varying
operating conditions in 1995 and the monthly average TSS in the effluent was 12 mg/L.
The highest monthly average for 1995 was 22 mg/L.
Floatables
The Warning Level for oil and grease is the same as the expected NPDES permit limits,
15 mg/L in weekly grab samples. The 1995 results indicate no violations of that threshold
(one sample from February of 1995 exceeded 15 mg/L due to a laboratory error). A sepa-
rate threshold was established for floatables (visible floating debris) which are assessed by
a different method from oil and grease. Floataales cause aesthetic problems; oil and grease
cause aesthetic as well as toxic problems. The floatables Warning Level was set in relation
to the performance of the future secondary treatment plant, which has a series of floatables-
removing skimmers. The expectation is that the final skimmer is redundant . If as much as
5 gallons of floating matter accumulates in that final skimmer over the course of a day, that
would indicate that it is not redundant and the upstream skimmers may be overloaded or
inefficient. The visual inspections will begin in 1998 and be conducted weekly. The design
of the present primary plant does not allow for any such quantification of floatables now,
and so the 1995 floatables results portion of Table 2-1 is blank.
MWRA - OUTFALL MONITORING REPORT: 1995 / 13
Plant Performance
The MWRA Caution Level for plant performance is the Association of Metropolitan
Sewerage Agencies' (AMSA) standard of 5 violations/year, while the Warning Level is the
EPA standard of noncompliance 5% of the time. Monitoring results indicate that 20 viola-
tions occurred in 1995, and that most of these violations were due to TSS and BOD
exceedances. Once the new treatment system is on line, and TSS and BOD are more effec-
tively removed, the frequency of violations is expected to drop below the threshold.
2.4 Monitoring Results
As part of the MWRA Harbor and Outfall Monitoring Project, concentrations of selected
nutrients, trace metals, and anthropogenic organic compounds were monitored in the efflu-
ent of the MWRA Deer Island Wastewater Treatment Plant as weil as in the influent and
effluents of the pilot secondary treatment plant. None of the contaminants will exceed
water quality criteria after the effluent has been diluted by seawater within a few tens of
meters of the outfall. Under typical conditions a 100-fold dilution will occur within that
area; it will always exceed 50-fold dilution, ensuring that the chemicals in effluent will pose
a minimal risk to aquatic life. A further degree of environmental protection will in the
future be provided by the improved removal efficiency of secondary treatment.
2.4.1 Effluent Characterization
Nutrients
In the 1995 DECS sampling program, total nitrogen (the sum of particulate organic and total
dissolved nitrogen) in the primary effluent ranged from 516 to 2,250 mM (7.2 to 31.5 ppm)
in grab samples. Approximately sixty-nine percent of the nitrogen in the effluent was pre-
sent as ammonia. Monthly total nitrogen loading ranged from 296 to 763 metric
tons/month (Figure 2-1) for Deer Island effluent. The total annual Deer Island discharge,
multiplied by 1.5 to include an estimate of Nut Island discharge, was 10,003 metric
tons/year. The NPDES program measured total nitrogen load at both treatment plants, at a
greater frequency than the DECS study, and as a composite rather than as a grab sample.
The variablility was lower in the NPDES data due to the composite sampling, and the annu-
al load was higher (11,460 metric tons/year). The NPDES data are a more reliable estimate
of the annual load due to compositing and the greater frequency of measurement whereas
the DECS study was nevertheless useful in providing additional information on the forms of
nitrogen and other nutrients in effluent.
800
FIGURE 2-1
Total Nitrogen and Particulate
Organic Nitrogen Loading in
Deer Island Effluent.
Organic Material
—®—Total Nitogen
In 1995, monthly BOD levels in Deer 700 }{ —@ Particiate Organic -™~
Island effluent ranged from 50 to 179 \
2 \
600
mg/L; seasonally, BOD tended to be
lower in the spring and highest in the
summer months. The BOD in Deer
0 ~
i
o L \ 7 \
vw wi
Island effluent averaged approximately
300
Loading (mtons/month)
102 mg/L during 1995.
200
The start up of the new primary treat-
ment system in January, 1995 did not ” i a a a
o
Jan-95 Feb-95 Mar95 Apr-95 May-95 Jun-95 Juk95 = Aug-95 Sep.95 Oct-95 Nov-95 Dec-05
Month Sampled
700
600
500
400
300
200
14/ OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
MI After nearly a decade of plan-
ning, design, and construction,
the MWRA started-up the new
Deer Island primary treatment
plant in January, 1995. The pri-
mary treatment process
involves removing solids from
sewage and chlorinating effluent
prior to discharge. A new sec-
ondary treatment facility is cur-
rently under construction.
Secondary treatment combines
a bacterial process to decompose
sewage with a physical settling
process. Whereas primary treat-
ment removes 30 to 35% of the
organic matter and 20 to 40%
of the toxic pollutants, sec-
ondary sewage treatment
results in removal of more than
75 to 90% of the organic matter
and most toxic pollutants prior
to effluent discharge..
result in a significant decrease in BOD from 1994 levels. This is to be expected, as much of
the organic matter in MWRA's system is dissolved, and not efficiently removed by primary
treatment. MWRA anticipates that completion of the secondary treatment facility will fur-
ther improve the effluent quality, and that BOD levels will drop substantially once this plant
is on-line. After startup of the secondary treatment system, it is anticipated that BOD levels
will drop to 10-15 mg/L. Results from the 1995 pilot secondary treatment plant study
showed a monthly average BOD of 11 mg/L.
Toxic Contaminants
Average effluent analyte concentrations (DECS) for the Deer Island Treatment Plant from
January to December 1995 are presented in Table 2-2. None of the mean concentrations of
analytes listed in the table exceed the dilution-adjusted water quality criteria (WQC). PCBs
are not listed in the table because discussions are underway with EPA to consider updating
the WQC for PCBs so they are expressed in terms consistent with the more sensitive analyt-
ical techniques in use today (MItchell et al. 1997). The WQC in Table 2-1 were adjusted for
the dilution factors adopted by the EPA for this outfall (364 for human health, 68 for chron-
ic, and 52 for acute WQC).
TABLE 2-2
Mean 1995 Effluent Contaminant Concentrations
Compared to Adjusted Water Quality Criteria
1995 Mean Effluent Human Health Chronic Acute
Parameter Concentration’ WOQC x 364 WQC x 68 WwaQc x 52
(ug/L) (ug/L) (ug/L) (ug/L)
Pesticides
Aldrin ND 0,027 NA 67.6
4,4-DDT 0.007 0.0087 0.068 68
Dieldrin ND 0.026 0.13 36.9
Endrin ND 364 0.16 1.9
Heptachlor 0.0025 0.102 0.245 28
Heptachlor
Epoxide ND 0.036 0.245 2.8
Lindane 0.018 6.8 NA 8.3
PAH
Acenaphthene 0.093 NA 48,300" 50,400*
Fluoranthene 0.23 15,300 1,090* 2080*
Naphthalene 1.6 NA NA 122,000*
=PAH 16.9 NA NA NA
Metals
Silver 3.95 18,200 NA 120
Cadmium 0.54 3,600 360 2200
Chromium (UI) 15.6 18,200 3,400 67,000
Copper 64.2 NA 197 151
Mercury 0.1 52.4 17 109
Nickel 6.3 4,880 560 3900
Lead 15 18,200 380 7300
Zine 749 NA 5,800 4900
‘Average concentration in samples
in which contaminant was detected.
Source: Buller et al., 1996.
ND = Not detected.
NA = Not Available
* Insufficient information for development of WQC.
NOEC used instead.
MWRA : OUTFALL MONITORING OVERVIEW REPORT: 1995 / 15
Toxicity
MWRA performs three different effluent toxicity tests: 1) acute mortality in marine mysid
shrimp; 2) chronic survival and growth in sheepshead minnow; and 3) chronic reproduc-
tion in red algae. Acute test limits have a NOEC of 20%, while chronic tests have a
NOEC of 10%.
In 1995, the results of the acute toxicity tests in shrimp had a range in NOEC of 5 to
20%, with an average of 14%. Seven of the twelve tests violated the 20% acute NOEC
limit. The 1995 chronic minnow test results averaged 42% with a range of 20 to 60%.
There were no exceedances of the 10% NOEC limit. In contrast, all of the red algae tests
failed. The chronic NOEC limit is 10%, while the test results were between 0.7 and 2%, Figure 2-2
with an average of 2%. These results as well as those from other treatment plants and Measure ements of Fecal Coliform
other practical test consider- in Effluent
ations have prompted the 1000000 ;
EPA to revisit the test i
species, and it is expected 100000
that sheepshead minnow
and red algae will be 10000 |
I
replaced in the permit.
Exploratory toxicity testing
conducted in 1995 include
1000
Fecal Coliforms per 100 mL
T
I
I
I
!
|
|
|
i
|
|
|
!
J
|
|
\
)
rt | err |,
|
the species Menidia and wo |
Arbacia. The two tests }
using Menidia showed a illite) Mit
20% NOEC. Six tests using ial
Arbacia showed a range of l \ i
|
10 to 100% NOEC, These
1234567 891011212345 678910112123 45678 9101112123 45678 9101112
are well above the 1.5% 1992 1993 1994 1995
NOEC being considered for permit limits, i.e. the effluent will not violate these toxicity
limits.
Pathogens
Fecal coliform levels in Deer Island effluent vary widely (Figure 2-2). While exceedances of
the daily maximum threshold occurred in 1995, the number of exceedances was reduced
from previous years, No monthly exceedances were observed in 1995 or in previous years.
This level of performance is expected to be further improved when the new treatment plant
is on-line. The new treatment plant will have a longer chlorine contact time, resulting in
increased pathogen destruction.
Solids
Average monthly TSS concentrations in the effluent from the Deer Island Treatment Plant
in 1995 ranged from 23 to 201 mg/L. The average TSS concentration was 63 mg/L.
Results from the 1995 pilot secondary treatment plant study showed a monthly average
TSS of 12 mg/L.
16 / OUTFALL MONITORING OVERVIEW REPORT: 1995 + MWRA
Floatables
Current sewage treatment operation includes regular and efficient removal of floatable mate-
rials early in the treatment process. As a result, substantial levels of floatables have not
been detected in the effluent. A more comprehensive procedure for assessing visible floata-
bles will be instituted when the secondary plant is on line.
2.4.2 Pilot Secondary Treatment Plant Results
Treatment Plant Effectiveness
Testing at the pilot seocndary treatment plant was conducted throughout 1995. The
removal efficiencies of the primary and secondary treatment process continued to be vari-
able; however results are encouraging as they indicate that the concentrations of many cont-
aminants of concern will be substantially reduced through secondary treatment.
The pilot secondary treatment plant was found to have very high removal efficiency in com-
parison to the primary effluent, averaging approximately 85% removed for total PAHs, total
DDTs, and total chlordane. High removal efficiencies (70-85%) were achieved for total
LABs, silver, copper, lead, and particulate organic carbon. Intermediate (20-70%) removal
efficiencies were indicated for total PCB, zinc, total phosphorus, and dissolved organic car-
bon. Lindane, cadmium, chromium, mercury, and biogenic silica were also estimated to be
in the intermediate removal efficiency range. Inefficiently (<20%) removed contaminants
include: molybdenum, nickel, and total nitrogen. The pilot secondary contaminant con-
centrations were all less than the Deer Island primary effluent contaminant concentrations
on the average (some individual samples of pilot secondary effluent may show higher con-
centration of the inefficiently removed contaminants such as molybdenum, nickel and total
nitrogen than the pilot plant influent). Compounds with the highest observed concentra-
tions for individual measurements (note that average concentrations were much lower)
were total PAH (3250 ng/L), LAB (2696 ng/L), molybdenum (27.8 pg/L), zinc (58 pg/L)
and total nitrogen (2315 pM). The 1995 pilot secondary treatment plant data are consistent
with the removal efficiencies used in the EPA SEIS to make impact predictions. As with the
primary treatment plant, none of the effluent contaminant concentrations exceed the most
stringent water quality criteria modified by their respective dilution factors.
Loading
Contaminant loading reductions approximating the removal efficiencies listed above can be
expected. The removal efficiencies estimated from the 1995 pilot secondary treatment plant
sample concentrations indicate that the loading of contaminants to Massachusetts Bay will
be significantly reduced.
Effluent Quality
The pilot secondary treatment plant data show that the secondary treated effluent will meet
all water quality criteria after initial dilution.
MWRA - OUTFALL MONITORING OVERVIEW REPORT: 1995 / 17
3.0 Water Column Monitoring Program
3.1 Water Column Issues
Potential water column issues due to the relocation of the out-
fall are associated with the effects of the effluent organic mate-
rial, nutrients, and toxic contaminants. Of these, changes in
the nutrient balance in Massachusetts and Cape Cod Bays
have the most potential for significant effects on the health of
marine life in the Bays.
I Te
a i
* Nearlietd Water
Column Locations.
@ Farfiold Water
Column Locations
3.1.1 Organic Material
Organic material occurs naturally in water bodies and may
also be introduced by wastewater effluents. Decomposition of
organic material consumes dissolved oxygen (DO). DO is oxy-
gen dissolved in water and available to marine mammals for
respiration. If DO concentrations are low, a condition known
as hypoxia, sensitive animals may suffocate. Hypoxia can
occur when the DO demand of decomposition is greater than
the natural resupply. The oxygen depletion rate is a measure
of this difference between DO supply and demand, and
20
ow
describes how quickly DO concentration decreases.
100 6s" ce Os! 70°00"
3.1.2 Nutrients FIGURE 3-1
Nearfield and Farfield water
Nutrients are necessary for the growth of all plants, aquatic and terrestrial. The amount of column sampling locations
nutrients in the water, along with several other factors, controls the growth of aquatic
plants, including algae. Since algae are the foundation of the aquatic food web, nutrients
have a great effect on how much life a marine ecosystem can support. In particular, there
are two basic ways in which nutrients from MWRA effluent can have a negative effect on
marine environments: through the effects of algae on dissolved oxygen concentration and
through changes in algal community structure. Nitrogen is the nutrient of greatest concern.
Low Dissolved Oxygen (Hypoxia)
An algal bloom is a burst of algal growth, which occurs when a variety of conditions come
together. A sufficiently high nutrient level is one of the requirements, but other factors such
as sunlight and temperature are also important. Algal blooms are the base of the food web,
without which fish, whales, and most other marine life would not survive. Algal blooms
are necessary, common occurrences in the marine environment, but they can be a cause for
concern, depending on the intensity and frequency of the bloom, and the types of algae
that bloom.
If a body of water receives too great a nutrient load, it may become subject to eutrophica-
tion: over-stimulation of algal growth and excessive algal blooms. When algae grow faster
than they are consumed, the excess algae die, sink to the bottom, and decompose.
Decomposition of the algae consumes DO, just as with the decomposition of the organic
material in discharged effluent as discussed in Section 2.1. This DO consumption can con-
tribute to the creation of hypoxic conditions.
Hf Algae Communities, The com-
position of the algal community,
or the relative numbers of vari-
ous algae species, is known as
the community assemblage.
Approximately 30 to 50 algae
species typically are observed in
the community assemblage mon-
itored by MWRA. These include
species commonly known as
diatoms, blue-green algae, and
flagellates. Flagellates are plank-
tonic algae that have self-pro-
pelled mobility, albeit limited.
Red tides are a specific kind of
dinoflagellate bloom that may
produce toxic chemicals. Some
red tides can result in mortality
of fish and other marine organ-
isms and toxicity of seafood.
UTFALL MONITORING REPORT: 1995 - MWRA
Algal Community Structure (Growth of Undesirable Algae).
Adding effluent to the marine environment may change the relative levels of different nutri-
ents so that undesirable algae dominate or are present along with useful algae. The nutri-
ent composition of effluent is different from that in Massachusetts Bay, and there is public
concer that undesirable algae may be better able to take advantage of this difference than
desirable algae. Two types of undesirable algae can have direct effects on the marine envi-
Tonment: 1) nuisance algae, such as brown and red tides, which affect the appearance of
the water; and 2) noxious algae, such as some red tides, which are toxic to marine mam-
mals, some fish, and, if concentrated in shellfish, to humans. Undesirable algae can also
have an indirect effect on the marine environment by out-competing another algal species.
If the out-competed species is a primary food source for a marine mammal, that animal
may suffer. For instance, it has been suggested that right whales in Cape Cod Bay are
linked through the food chain to a kind of algae that might be affected by effluent-induced
changes in nutrient concentrations.
3.1.5 Toxic Contaminants
Toxic contaminants are not always toxic. They are harmful at and above certain concentra-
tions, but at lower levels they may be harmless. Some even may be essential to life (e.g.
copper and zinc, whereas mercury and lead are not). The timing of exposure is also an
important factor: temporary exposures are less harmful than constant ones. This is reflect-
ed in higher water quality criteria for acute exposure than for chronic exposure. Animals
passing briefly by the outfall would be only temporarily exposed. Because the harmful
effect of contaminants decreases with decreasing concentration, the dilution of the effluent
is key to minimizing the impact of the outfall.
The potential for increased levels of toxic contaminants in the vicinity of the new outfall is
generally low. The new outfall will minimize the environmental impact of effluent by maxi-
mizing dilution. Because outfall relocation is unlikely to have a significant effect on the
concentrations of toxic contaminants in waters of Massachusetts Bay, toxic contaminant
concentrations are monitored in the other three program areas but not in the water column
program. Because adequate dilution is central to the expectation of no impact, the effluent
dilution achieved by the diffuser will be evaluated using data obtained from the plume
tracking surveys (described below).
3.2 Monitoring Program Design
The water column monitoring program is designed to provide measurement of water quality
and plankton data in Massachusetts Bay and Cape Cod Bays. The data will help detect
changes in the water column of the Bays resulting from the relocation of the effluent outfall.
The monitoring program, which began in 1992, is designed to characterize background
water column conditions before completion of the outfall. Once the outfall is on line, water
column monitoring data will be compared to background data and any impacts to
Massachusetts and Cape Cod Bays will be assessed.
The five major components of the water column monitoring program, nearfield surveys,
farfield surveys, plume track surveys, moorings, and remote sensing, are outlined below.
These components are designed to provide comprehensive coverage of water quality condi-
tions in Massachusetts and Cape Cod Bays.
MWRA - OUTFALL MONITORING REPORT: 1995 / 19
Nearfield Surveys Hi Chlorophyll is the green pigment
Nearfield water column surveys are designed to collect frequent intensive sets of water in plants that supports photo-
quality and plankton data near the outfall location. Impacts are most likely to be measur- synthesis. Chlorophyll is used as
able near the outfall site, and are likely to be confined to the nearfield area. The nearfield a measure of the algal biomass,
area is defined by a rectangle surrounding the 1.2 mile outfall diffuser line at a distance of 3 the total amount of algae in the
miles. The stations are spatially intensive to document the decrease of impacts with dis- water. The type of chlorophyll
tance from the outfall in the region where the decrease is expected to be strongest and most Most commonly measured is
detectable. Data are collected at 17 locations (Figure 3-1) in 17 annual surveys. These sur- chlorophyll a.
veys provide vertical profiles of physical, chemical, and biological water column characteris-
tics throughout each year, identifying seasonal cycles and events of interest (e.g., algal
blooms).
During each nearfield survey, temperature, salinity, dissolved oxygen, chlorophyll fluores-
cence, light transmission, and photosynthetically available light are electronically measured
in situ throughout the depth of the water column. Water samples are collected at selected
stations and depths in the water column for laboratory analysis of constituents including
nutrients, chlorophyll, suspended solids, dissolved oxygen, phytoplankton, zooplankton,
primary productivity, and respiration. The primary productivity (i.e., photosynthesis, the
algal growth rate) measurements are performed to evaluate how the algae are responding
to ambient nutrients and light. The respiration measurements evaluate the rate of oxygen
consumption due to metabolic activity including degradation of algal biomass and other
organic matter. Observations of whales, other marine mammals, and sea turtles are also
performed during the nearfield surveys.
Farfield Surveys
Farfield water quality surveys are designed to collect intensive sets of water quality, plank-
ton, and primary productivity data over a broad spatial scale, and to cover Massachusetts
and Cape Cod Bays. Stations are not spatially intensive as they are in the nearfield, but are
spread out over the Bays with adjustments to cover special resource areas and to detect the
influence of coastal and offshore sources of nutrients to the Bays. The main purpose of the
farfield surveys is to determine differences across the bays and assess seasonal changes over
a large area, (e.g., relating trends observed in the nearfield area to the surrounding region).
Six farfield surveys are conducted each year collecting water quality data at 26 stations
throughout Massachusetts and Cape Cod Bays (Figure 3-1). Plankton and primary produc-
tivity data are collected at selected stations. Farfield and nearfield methods are comparable.
Plume Tracking Surveys.
Plume tracking surveys are performed to determine the location and physical, chemical and
biological characteristics of the effluent discharge plume leaving the outfall and mixing with
ambient waters. Sampling will include measurement of salinity, temperature, dissolved oxy-
gen, chlorophyll, and suspended solids. The dilution and transformation of components
characteristic of the effluent will be tracked using salinity and nutrients as well as other
chemical, isotopic, and microbial constituents. Intensive studies will begin when the outfall
is on line; some preliminary plume tracking studies of an exploratory nature were per-
formed in 1995.
20 / OUTFALL MONITORING REPORT: 1995 - MWRA
li MWRA has conducted extensive
water quality modeling studies
to evaluate the potential effects
of outfall relocation. The results
of the modeling studies indicate
that outfall relocation will sig-
nificantly improve conditions in
Boston Harbor: i.e. lower nutri-
ent and chlorophyll concentra-
tions and increased dissolved
oxygen concentrations. Effects
in the Bay would be confined to
the immediate vicinity of the
future outfall. The modeling
study was used to assist in the
design of the water column mon-
itoring program, which will be
used to verify the modeling
study results.
I Biomass is the total amount
of a biological material. Algal
biomass is a measure of the
total amount of algae present
in the water.
Moorings
A mooring is maintained by the US Geological Survey near the future outfall site to measure
currents, temperature, salinity, light transmission, chlorophyll, and sediment processes. In
addition to a mooring, which physically consists of instruments suspended from a float and
anchored by a weight, the USGS also deploys tripods mounted on the sea floor. The pur-
pose of moorings and tripods is to obtain continuous data at a location. The outfall moni-
toring program uses the data to capture temporal (i.e., time-dependent) variations in water
quality between nearfield surveys.
Remote Sensing
Satellites provide remote sensing imagery which the outfall monitoring program uses to cap-
ture spatial variations in water quality on a regional scale. The images provide a snapshot
of sea surface temperature over the Bays at one time. Sometime after 1995, chlorophyll
data will also become available. Remote sensing fills in the information between survey
sample locations. Data from remote sensing complements the data from the ship surveys
and moorings.
3.6 Threshold Comparison
MWRA is developing thresholds for several water column monitoring parameters in order to
assess the potential impacts of the new outfall. The trigger parameters, threshold levels,
and 1995 monitoring results for the water column are summarized on Table 3-1. A detailed
discussion of the thresholds and current status of compliance with thresholds is provided
below.
Most of the threshold levels are expressed as a number in relation to a certain interval of
time and space. The relevant data are pooled over those intervals and then compared to
the threshold number. The pooling may be done by calculating an average, a geometric
mean (e.g. bacteria) or other statistic (e.g. benthic diversity). Pooling yields a number
which is less extreme than that of the worst-case individual reading, and so the spatial and
temporal intervals have to be chosen carefully - large enough to reflect the ecological
response scale of the resource to be protected but small enough to not mask transient prob-
lems that occur. The thresholds are designed to be compared to pooled rather than individ-
ual data because the latter are dependent on the sampling effort. As an example of how
the pooling is done: monthly mean DO in nearfield bottom waters is calculated by averag-
ing the deepest DO measurements from all the nearfield stations during one survey; that
result is then averaged over all the surveys (there are up to two) within a calendar month to
give the nearfield monthly mean.
Dissolved Oxygen Concentration and Saturation
Aquatic animals are sensitive to the concentration of DO in the water column. Low levels
of DO can have negative impacts on marine life. Because of the importance of DO, the
state has set a water quality standard that a discharge should not cause DO to fall below 6
mg/L nor below 75% of saturation in Massachusetts Bay.
The DO percent saturation threshold is unique in that it has already been exceeded in the
baseline period before the future outfall is operational. The issue of causality implied in
the state standard is pivotal in such a case and will be decided on by the OMTF. Water
quality modeling studies have indicated that dissolved oxygen levels will improve at the
MWRA + OUTFALL MONITORING REPORT: 1995 / 21
Parameter
Dissolved oxygen
concentration in
TABLE 3-1
Water Column Thresholds Compared to 1995 Monitoring Results
Caution Level
Monthly mean DO is less than 6.5 ppm or 80% of
saturation levels for any one month during stratifica-
Warning Level
Monthly mean DO is less than 6 ppm
or 75% of saturation levels for any one
1995 Results
DO saturation below warn-
ing level in September
concentration in
Stellwagen Basin
bottom waters
saturation levels for any one month during stratifica-
tion (June-Oct.)
or 75% of saturation levels for any one
month during stratification (June-Oct.)
Nearfield region | tion (June-Oct.) month during stratification (June-Oct.) (74.3%).
bottom waters (See Table 3-2)
Dissolved oxygen | Monthly mean DO is less than 6.5 ppm or 80% of Monthly mean DO is less than 6 ppm DO saturation below warn-
ing level in October
(71.0%).
(See Table 3-2)
Dissolved oxygen
depletion rate in
DO depletion rate is greater than 1.5 times the
baseline rate for any one month during stratification
DO depletion rate is greater than 2
times the baseline rate for any one
1992-95 Average Baseline
Rate:
Neartield region
the baseline annual mean, 2.93 pg/L.
than 2 times the baseline annual
mean, 3.90 g/L.
Nearfield region (June-Oct,), -0.041 mg/Liday. month during stratification (June-Oct), | -0.027 mg/Lday
bottom waters -0.054 mg/L/day.
1995 Rate:
-0.027 mg/Liday
Chlorophyll in Annual mean concentration greater than 1.5 times Annual mean concentration greater 1992-95 Baseline:
1.95 ug/L
1995: 1.39 g/L
assemblage in
Nearfield region
community towards an inshore community,
Inshore: Acartia, Eurytemora, Centropages hamatus
Offshore: Calanus, Pseudcalanus, Centropages typi-
cus, Oithona
Nearfield: Transitional between two regions.
Chlorophyll in Season mean concentration exceeds 95th percentile | None. Spring: 1.02 mg/L
Nearfield region of the baseline seasonal distribution. Summer: 0.73 pg/L
Spring: 2.38 pg/L. Fall: 2.58 jag/L
Summer: 2.37 pg/L
Fall: 4.56 pg/L
Nuisance algae in | Alexandrium tamarense None. Alexandrium tamarense
Nearfield region | Season mean population densities exceed 95th per- Spring: 0 cells/L
centile of the baseline seasonal mean. Summer: 0 cells/L
Spring: 4.56 cells/L Fall: 0 cells/L
Summer: 1100 cells/L (See Table 3-3)
Fall: 8.67 cells/L
PSP extent in New occurrence. PSP has never been observed None. No occurrences.
Farfield region at 3 of the 18 monitoring stations (see Table 3-4),
Zooplankton Nearfield assemblage shifts from a transitional None. Transitional assemblage in
nearfield region.
tion at new outfall
location
Initial effluent dilu-
None.
Effluent dilution less than that set by
the NPDES permit.
No data until outfall is
online.
22 / OUTFALL MONITORING REPORT: 1995 - MWRA
future outfall site as a result of outfall relocation and
a secondary treatment (Figure 3-2). In the post-dis-
~ charge period, when the Contingency Plan becomes
2 active, action will be taken in response to a violation.
— The first action to be taken is to notify the OMTF.
fas) Even if low DO is determined to be unrelated to the
om) MWRA discharge, it is appropriate to have in place a
JF MAM J J AS ON D mechanism for keeping the OMTF immediately
—— Present Oufalls with Primary informed of episodes of low DO, given the ecological
snsnene Future Oulfall with Secondary importance of that parameter. Actions could also include further water quality modeling
Treatment studies to evaluate the cause of the violation.
Figure 3-2
Water quality modeling results In 1995 the lowest nearfield monthly mean DO concentration, 6.9 mg/L in September, was
near future outfall: Existing above the caution level of 6.5 mg/L (Table 3-2). The lowest individual measurement was
(2192) conditions and te out 5.7 in September. During the entire baseline period to date (1992-95), the lowest nearfield
ment (Source: HydroQual. i995) monthly mean was 6.5 mg/L in September 1994, and the lowest individual measurement
was 4.8 mg/L in October 1994.
In Stellwagen Basin in 1995, the lowest nearfield monthly mean DO concentration, 6.7
mg/L in October, was also above the caution level of 6.5 mg/L (Table 3-2). The lowest
individual measurement was 6.6 mg/L in October. During the entire baseline period to date
(1992-95), the lowest nearfield monthly mean was 6.6 mg/L in October 1994, and the low-
est individual measurement was 6.3 mg/L, also in October 1994.
In 1995 the lowest nearfield monthly mean DO percent saturation, 74.8% saturation in
September, fell below (i.e., violated) the warning level of 75% saturation (Table 3-2). The
lowest individual measurement was 64.2% saturation in September. During the entire base-
line period to date (1992-95), the lowest nearfield monthly mean was 74.0% saturation in
October 1994, and the lowest individual measurement was 55.6% saturation, also in
October 1994.
In Stellwagen Basin in 1995, the lowest nearfield monthly mean DO, 71.0% saturation in
October, also violated the warning level (Table 3-2). The lowest individual measurement
was 69.3% saturation in October. During the entire baseline period to date (1992-95), the
TABLE 3-2
Minimum DO Concentration and Percent Saturation:
1995 and Baseline Period
Location & Trigger 1995 Baseline (1992 - 1995)
Parameter 7 a 7 oy _
Individual Minimum | Monthly Minimum Individua! Minimum ent iia
Nearfield Concentration 5.7 mg/L | Sept.95 | 6.9 mg/L | Sept.95 | 4.8 mg/L Oct. 94 6.5 mg/L Sept. 94
Stellwagen Concentration 6.6 mg/L Oct. 95 6.7 mg/L | Oct. 95 6.3 mg/L Oct. 94 6.6 mg/L Oct. 94
Nearfield % Saturation 64.2% Sept. 95 74.8% Sept. 95 55.6% Oct. 94 74.0% Oct. 94
Stellwagen % Saturation 69.3% Oct. 95 71.0% Oct. 95 68.2% Oct. 94 72.6% Oct. 94
MWRA + OUTFALL MONITORING REPORT: 1995 / 83
lowest monthly mean was 72.6% saturation in October 1994, and the lowest individual
measurement was 68.2% saturation, also in October 1994.
In summary for 1995, both the nearfield and Stellwagen Basin monthly mean DO saturation
levels fell below the caution and warning levels. The nearfield region experienced a mini-
mum monthly mean DO saturation of 74.8% in September, while Stellwagen Basin experi-
enced a minimum monthly mean of 71.0% in October.
Dissolved Oxygen Depletion Rate
The DO depletion rate thresholds are based on the calculated average rate from the baseline
period. The rates over the four years of baseline to date vary from a low of -0.024
mg/L/day in 1992 to a high of -0.031 mg/L/day in 1994. Both 1994 and 1995, which expe-
rienced low DO concentrations and saturation levels, had higher rates of DO decline than
1992 and 1993. Based on the data collected to date, the interim threshold for the average
baseline DO depletion rate is.-0.027 mg/L/day (Table 3-1). As additional baseline data are
collected, this value will be updated. Based on this average value, the DO depletion rate
thresholds would be -0.041 mg/L/day for the Caution Level and -0.054 mg/L/day for the
Warning Level. The 1995 DO depletion rate was -0.027 mg/L/day, which is by coincidence
the same as the average, and below the Caution and Warning Levels.
Chlorophyll and Nuisance Algae
Adding effluent to the marine environment could change the amount of nutrients or the rel-
ative levels of different nutrients so that excessive or prolonged algal bloom could occur. As
discussed earlier, the settling and decomposition of algal biomass in the bottom water can
lead to low DO conditions. Algal biomass is most commonly measured as chlorophyll, a
photosynthetic chemical in all green plants. Chlorophyll a is the type of chlorophyll mea-
sured in the EPA approved standard test for chlorophyll and adopted by the MWRA, and is
the form implied when the “a” is omitted.
As there are no state or federal regulations for chlorophyll, the Warning Level was devel-
oped based on expert peer review comments to the OMTF. The commentors agreed with
the rule of a thumb that appeared in 1993 in the National Oceanographic and Atmospheric
Administration's Estuarine Eutrophication Survey: “normal blooms become problematic
when chlorophyll values reach 20 ug/L.” The commentors wanted a greater level of protec-
tion for Massachusetts Bay, however, because present levels are so much lower (2-3 ug/L),
and deleterious changes would be apparent long before the chlorophyll reached the NOAA
level of 20 ug/L. Therefore the Warning Level was set at twice the baseline value of the
annual mean nearfield chlorophyll concentration, or well before there is a likelihood of bio-
logically significant change.
In addition to the trigger parameter above which focuses on the annual average, another
was established which recognizes the inherent seasonality of chlorophyil over the year and
is designed to protect against unusually high algal biomass in any one season. By allowing
for seasonality the new trigger parameter would be more sensitive to meaningful change.
The statistic chosen to reflect the meaning of “unusual” in this case was chosen to be the
95th percentile. A measurement would be deemed to be unusually high if it were to exceed
95 percent of the baseline values. There is a 5 percent chance of a false alarm with this
approach but it is appropriate nevertheless to notify the OMTF immediately of such an
occurrence.
24 / OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
TABLE 3-3 The interim chlorophyll thresholds
Plankton Thresholds Comparison (shown on Table 3-3) were devel-
oped from the existing four years of
Trigger Caution Warning 1995 baseline monitoring data. The
Location Paramater Season Level Level Results chlorophyll concentrations for 1995
Nearfickd | AnnualMean | Year | 293 ug/L 390ugl | 139 ug/L were below the existing threshold
Chlorophyll values.
Concentration
A Nuisance and noxious algae natu-
Nearfiekd Seasonal Mean | SPrng 2S uot a 12 not rally occur in Massachusetts and
Chlorophyll Summer 2.37 pg/L none 0,73 pg/L C y Cod Bays i I b
Concentration | Fal 4.56 jig/L none 2.58 gil Ape Lod ays tn smal numbers
So 156 “ 7 ma annually. There is public concern
Nearfield | Seasonal Density pring me oes none os that effluent nutrients could stimu-
ot Alexandrum Summer | 1,100 cells/L none 0 cells/L late a red tide or similar noxious
Fall 8.67 cells/L none 0 cells/L algae bloom in the vicinity of the
Nearfield | Seasonal Density Spring 2,670 cells/L. none 2,000 cells/L new outfall. At the 1996 peer
of Nitzschia | Summer} 55,000 cells/L none 20,000 cells/L review workshop, it was recom-
pungens Fall 5.42 x 10° cells/L none 16,000 cells/L mended that the Massachusetts
Nearfield | Seasonal Density Spring } 2.63 x 10° cells/L none 0 cells/L shellfish toxicity monitoring pro-
of Phaeocystis | Summer 0 none O cells/L. gram be used to set red tide
pouchetii Fall 52,000 cells/L. none O cells/L Caution Levels. The state program
monitors the toxicity of Paralytic
Shellfish Poisoning (PSP) at shell-
fish beds along the edge of Massachusetts and Cape Cod Bays. A list of Department of
Marine Fisheries shellfish monitoring stations is provided in Table 3-4.
To date, no shellfish toxicity has been observed at the monitoring stations in Dennis,
Barnstable, or Provincetown. Prior to the large Alexandrium bloom which occurred in
1993, toxicity had not been observed beyond the Cape Cod Canal. However, toxicity was
observed for the first time in Sandwich as a result of the 1993 bloom. Such an occur-
rence will be viewed as a trigger parameter for contingency planning in order to fully
evaluate its origin.
TABLE 3-4 The nuisance algae thresholds are
Shellfish Monitoring Stations for PSP being developed from the baseline
conditions. The Caution Levels will
be set as the 95th percentile of sea-
Gloucester-Annisquam Yacht Club Rockport-Granite Street sonal mean concentrations of the
Hull-Pt. Allerton Cohasset-Border Street three target species of nuisance algae
Cohasset-Little Harbor Scituate/Marshfield-South River Humarock (Table 3-3). In 1995, two of the
Scituate-Scituate Harbor Marshfield-Green Harbor three species were undetected in the
Marshfield-Damon’s Point Duxbury-Eaglenest Creek monitoring samples. The potential
Plymouth-Manomet Point Plymouth-Plymouth Harbor presence of the third target species
Sandwich-Cape Cod Canal (east entrance) Plymouth-Ellisville Harbor was suggested by low concentrations
Dennis-Sesuit Harbor Sandwich-Sandwich Harbor of related indicator species.
Bamstable-Marispan Creek
Provincetown-The Dike
MWRA + OUTFALL MONITORING REPORT: 1995 / 25
Zooplankton
Zooplankton assemblages vary with location in Massachusetts Bay. The species composi-
tion of inshore communities is dominated by Acartia, Eurytemora, and Centropages hama-
tus, while the species composition of offshore communities is dominated by Calanus,
Pseudocalanus, Centropages typicus, and Oithona. The nearfield region represents a tran-
sition between the two communities.
The zooplankton species in inshore communities are known to require the high concentra-
tions of nutrients and algae that are found in Boston Harbor for maximal growth and repro-
duction. Once the new outfall is online, the nutrient concentrations in both the Boston
Harbor and the nearfield region may change. The zooplankton community in Boston
Harbor may change beneficially toward that presently in Massachusetts Bay. The Caution
Level seeks to protect the zooplankton community in the nearfield of Massachusetts Bay
from changing undesirably to one similar to that presently in the Harbor.
Dilution
Since all evaluations of toxic impacts depend on concentrations after initial mixing, the
MWRA will measure the actual dilution of effluent by seawater around the new outfall to
test predictions of effluent dilution. Testing will focus on measurements of tracers to deter-
mine dilution in the immediate discharge mixing zone of the diffuser. The results will be
compared with predictions of contaminant concentrations. Because EPA dilution estimates
are very conservative, it is extremely unlikely that actual dilution will be less than the EPA
predicted dilution. However, if the study showed that real dilutions were less than antici-
pated and did not reduce toxic contaminant concentrations enough to protect the environ-
ment, the EPA and the state could revise MWRA‘s NPDES permit by lowering the allowable
discharge concentrations. Thus, effluent dilution tests provide a Caution Level which would
lead to revision of Caution and Warning Levels for toxic contaminants if it were exceeded.
As the new outfall is not on-line, no data is available to evaluate this trigger parameter.
3.4 Monitoring Results
The behavior of the Massachusetts Bay system is primarily controlled by the annual weath-
er patterns and cycle, although the individual system components (physical, chemical, and
biological) are also largely influenced by complex system interactions (Figure 3-3).
The monitoring program measures the annual behavior of the Bay system and provides data
sufficient to quantify the annual variability of each parameter. In 1995 the behavior of the
Bay system was similar to that observed in previous years. The following sections present
the components of the annual Bay cycle as they were measured in 1995.
Physical Characterization of the Water Column
The annual cycle of the Massachusetts Bay system begins in late winter when the Bay is
unstratified. Water temperature and salinity are vertically uniform throughout the water
column. As the snow melts in the spring, the runoff increases freshwater input to the Bay
from the Merrimack, Charles and other rivers (Figure 3-4). This fresh water runoff enters
the Bay at the surface, and because it is less dense than the salty water in the Bay, it stays
on the surface. As a result, a vertical salinity gradient develops (Figure 3-5).
Simultaneously, as the days get longer, the sun heats the surface water and a vertical tem-
Wi Water density is a function of
water temperature and salinity.
Density increases with decreas-
ing temperature and increasing
salinity. When the water column
is unstratified, the density of the
water is similar from top to bot-
tom, and mixing of the entire
water column can occur. When
the water column is stratified,
two distinct layers exist in the
water column: the surface layer
which is in contact with the
atmosphere and the oxygen it
contains, and the bottom layer
which is isolated from sources of
oxygen. These two layers are
separated by strong differences
in density.
26 / OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
perature gradient begins to develop (Figure 3-6). By the end of the spring (late May) the
water column is stratified (Figure 3-7).
During the summer, the water column becomes more stratified due to continued solar heat-
ing at the surface. Storms and upwelling events can temporarily break down this stratifica-
tion and mix the water column. Two upwelling events are evident in the 1995 data shown
in Figure 3-6 (early July and mid-August).
During early-July and mid-August the surface water temperature drops substantially as cool-
er bottom waters are brought to the surface by upwelling. Bottom water temperatures are
unaffected by upwelling.
In the fall, the water column completely re-mixes in a process known as overturn.
Overturn occurs because as the days get shorter and cooler, the surface water cools. When
the density of the surface water becomes less than that of deeper waters, it sinks. This
process generally takes place in October, after which time the water column gradually and
uniformly cools throughout the winter. In 1995 a major overturn event occurred in October
as seen in Figures 3-6 and 3-7 with overturn complete in November.
Plankton and Chlorophyll
Typically there are two major plankton blooms each year. The increasing sunlight and
water temperatures in spring trigger the first phytoplankton bloom, and turnover with its
inherent mixing drives another phytoplankton bloom in the fall. An increase in the zoo-
plankton population follows each phytoplankton bloom, as phytoplankton are the main
food source for zooplankton. Grazing of phytoplankton by zooplankton controls the mea-
Figure 3-3
‘Annual Water Column Cycle sured size of phytoplankton blooms and often ends them. The significance of zooplankton
of Massachusetts Bay
Late Fall— Spring Summer Fall
Late Winter ‘com shorter
©: jonger, 0; cooler days
UNSTRATIFIED days DEVELOPING STRATIFICATION STRATIFIED STRATIFICATION BREAKDOWN
Physical T uniform \ TT at surface TT, Tsurf > Tbottom Tsurt J
Temper § uniform § 1 at surface Ssurt < Sbottom => mixing
snow melt/runoff \
river discharge
i limited late winter/
Biology, Jankton activity | spring blooms fall bloom
generally increasing { densities \, generally decreasing densities
j i decreasing surface surface t
Nutrients uniform concentrations depletion = uniform
Dissolved . bottom bottom T
Oxygen uniform depletion — uniform
Discharge (ft°/sec) Precipitation (inches)
Discharge {ft*/sec)
MWRA + OUTFALL MONITORING OVERVIEW REPORT: 1995 / 27
{a) Boston Area Precipitation
3.0 3.0
Source: Northeast Regional Climate
2.5 25
2.0 20
15 15
1.0 10
0.5 | | | 05
oo dl pall both 1s Tile i | Jb td Pam 00
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dee
(c) Charles River Discharge
1000 100
Source: USGS |
800 \ \ 800
soo Mel iN a \ soo
400 f 400
WY a1 Medinn Flow = 291 cfs nM aw WY Aa
200 WON (A _T ~~ 909
NAA
0 0
Jan Feb Mar Apr May Jun Jol Aug Sop
(b) Merrimack River Discharge
Oct Nov Dec
35000 45000
30000 ft Source: USGS 30000
25000 25000
20000 n\ \ \ 20000
15000 [\ \/ AW \ 15000
veo (LA \ A XN veone
5000 NN Wwyy An 7 AA Medign Flow = 5520 of i
— ad I A Ve Ae 5000
sam Feb Mar Apr May Jun Jil Aug Sep Oct Nov Dec °
Figure 3-4
1995 Daily Precipitation and
grazing on phytoplankton was demonstrated during the 1995 spring bloom. A fourfold River Discharge Data,
increase in zooplankton abundance coincided with a tenfold decrease in phytoplankton
densities in March.
In 1995, as in previous years, spring and fall blooms occurred (Figure 3-8). The size of
the 1995 spring bloom was similar to those in previous years. However, algal biomass (as
measured by chlorophyll) was lower during the summer, and as an annual average, was
lower in 1995 than in previous years. On the other hand, the magnitude of the fall bloom
was the second largest recorded in the four-year baseline period. For the most part, the
1995 seasonal phytoplankton blooms (spring and summer peaks) in 1995 were dominated
by centric diatoms. The exception was dominance by pennate diatoms during the fall
bloom. Zooplankton also showed the typical seasonal changes and peaks in numbers,
with copepods (which are the primary food for baleen whales) dominating the zooplank-
ton community.
There was no evidence in 1995 of any significant occurrence of the three toxic or nui-
sance plankton species monitored by the MWRA monitoring program. There were also
no occurrences of shellfish toxicity reported by the Massachusetts Division of Marine
Fisheries in 1995.
Merrimack and Charles Rivers
Temperature (°C)
Salinity (PSU)
28 / OUTFALL MONITORING REPO
33.0
: 1995 + MWRA
33.0
Nutrient Cycle
The nutrient cycle in Massachusetts Bay
is closely linked to the physical and
biological changes that take place
through the year. Nutrients, like the
physical parameters, become vertically
mixed during the winter, and begin the
year at their highest levels (Figure 3-9).
The spring plankton bloom partially
30.5
depletes the nutrients throughout the
water column, as phytoplankton use
the nutrients as they grow. As spring
‘USGS Mooring Surface (Sm)
weeeee USGS Mooring Bottom (30m) 30.5
© HOM Surface
A __HOM Bottom
and summer progress, continued plank-
ton growth and stratification cause
30.0
30.0
Jan Feb Mar Apr May, Jun Jul =A Sep Oct, Sve nutrient depletion in the surface water.
Figure 3-5 Lack of algal growth prevents nutrient
1995 Moored Salinity depletion in the bottom layer. In fact, plankton death and subsequent settling to and
Sensor Data decomposition in the bottom layer cause nutrient concentrations to increase somewhat in
the bottom waters. Stratification prevents the nutrients in the bottom layer from vertical-
ly mixing into the surface layer. Overturn releases the nutrients trapped in the bottom
waters to mix throughout the water column (Figure 3-9).
Upwelling events during the summer can release some of the nutrients trapped in the bot-
tom layer into the surface layer. Nutrient releases into the surface layer can result in
increased phytoplankton growth. In 1995, the mid-August upwelling event described earli-
er, resulted in a modest increase in phytoplankton density (as measured by chlorophyll a,
Figure 3-8).
Dissolved Oxygen
FIGURE 3-6 As with nutrients, dissolved oxygen (DO) is closely linked to the physical and biological
1995 Moored Temperature changes in the Bay. Water column DO concentrations are the highest during the winter and
Sensor Data early spring (Figures 3-10 and 3-11) and
3 20 are well mixed throughout the water
eH 1, column. The highest DO concentration
measured in bottom waters (11.2 ppm)
16 in 1995 occurred in late February, and
14 Was lower than that observed in previ-
ous years.
12
io Once the water column is stratified, the
bottom waters are effectively cut off
}8 from the atmosphere (the source of
. 6 DO). However, consumption of DO
Malt via respiration continues. As a result,
ee pene iRsucaig Sues ey] | * bottom water DO concentrations
Ss Nowsuece "| | decline continuously throughout the
een stratified period. Mixing or upwelling
0
Jul Aug Sep Oct Nov Dec
Chlorophyll a
(g/L)
In-situ. Chlorophyll a In-situ
In-situ. Chlorophyll a
In-situ. Chlorophyll a
a
3
o
MWRA + OUTFALL MONITORING REPORT: 1995 / 29
Density (g/L)
21.5 22.0 22.5 23.0 23.5 24.0 24.5 25.0 25.5 26.0 26.5
0 + 0
|
5 4: Early August | } 5: Barly September 6: Early October \ 2 Mid-May : Barly March
q 5
[_3: Barly July 7: Late November
10 L |
== ae »
15 oS.
oT iN \ 15
_ 20 N 20
= Naw \
Ss
S 1s 25
; ) AS
30 | 30
35 \ ‘\ 35
4 d \ “
45 a 45
50 50
FIGURE 3-7
1995 Seasonal Density Cycle
in the Nearfield
1995 Annual Mean = 1.39 —o—1995 ‘
L 10 lf As winds blow from the west and
southwest, surface waters are
on 7 IN 5 blown away from the coast.
ee HK. _ A L Ne, | ; Colder bottom waters move in
Jan Feb Mar Apr May Jun Jul Aug " Sep Oct Nov Dec towards shore, and then upwards
15 to replace the warmer outgoing
1 #1 ——
994 Annual Mean = 1.96 1 surface waters. This process is
10 known as upwelling, and is expe-
x rienced by beachgoers as cold
th tte tt Maran te tae
o
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec | | The saturation level of dissolved
1993 Annual Mean = 2.36 | 8 oxygen varies with temperature.
Tr 10 Cooler water can hold more DO.
Therefore, DO concentrations
T A 5 will decrease naturally as the
ee ee Ty tt L \ water column warms during the
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ° spring and summer.
1992 Annual Mean = 2.08 [#1992] .
10
FIGURE 3-8
T 5 1992-1995 Chlorophyll a
bet tii ett | Averages in the Nearfield
* to) (Error bars represent +/- one
Feb
standard deviation.)
$0 / OUTFALL MONITORING REPORT: 1995 - MWRA
Nearfield (N16, N04, NO7, N20) events can bring DO to the bottom water, as seen in results from
DINWitrate + Nitrite + Ammonium) (yM)
o 123 45 6 7 8 3 10 11 12
the upwelling event observed during July 1995 (Figure 3-10).
The fall water column overturn ends the isolation of the bottom
layer and results in increased DO concentrations in the bottom
waters. Minimum DO concentrations in the bottom water are
reached just before overturn, and in 1995: 5.6 mg/L in Cape Cod
Bay, 5.7 in the nearfield region and 6.6 mg/L in Stellwagen
Basin (Figure 3-11). The survey-average minimum DO concen-
trations in the nearfield were higher in 1995 than in 1994,
although the 1995 concentrations were still significantly lower
than in 1992 and 1993. The lower minimum concentrations in
1994 and 1995 were caused by lower pre-stratification DO con-
centrations in late spring, and faster rates of DO decline during
the stratified period (Figure 3-12). The faster rates of DO decline
in 1994 and 1995 were driven by warmer bottom water tempera-
tures.
O 30 60 SO 120 150 180 210 240 270 300 330 380
T ae! t
o 30 60 90 120 150 180 210 240 270 300 330 360
Oo 30 60 30 120 150 160 210 240 270 300 380 360
Productivity and Respiration
Both productivity and respiration varied widely over the year.
The periods of peak productivity in 1995 occurred before stratifi-
cation in April, and after overturn in October. These periods
O 30 60 80 120 150 180 210 240 270 300 330 360
ullan Day correspond to times of a well-mixed, nutrient-rich water column
Figur 4-16, Nearfield DIN concentrations for 1992-1995.
FIGURE 3-9
Nearfield DIN
Concentrations FIGURE 3-10
for 1992-1995 1992-1995 Dissolved Oxygen Cycle in Surface and Bottom Waters in the Nearfield
(Error bars represent +/- one standard deviation.)
13 - 13
4 |
12 ie : . 12
11 T f+ |_|
LN o |
|
Ay
CA
DO (mg/L)
°
|b
=
ae ae
L
iL 6
Open Symbols = Surface
Filled Symbols = Bottom
5 5
Jan-92 Apr-92 Jul-92 Oct-92 Jan-93 Apr-93—-Jul-93.- Oct-93. Jan-94 Apr-94 Jul-94 Oct-94 Jan-95 0 Apr-95— Jul-95 Oct-95.
13
12
i
0
DO (mg/L)
Ney
5
MWRA - OUTFALL MONITORING REPORT: 1995 / 81
|_—nrd
a
\
awa
ae!
XJ
¢
Open Symbols = Surface
Filled Symbols = Bottom
| | i
Jan-92 Apr-92 Jul-92 Oct-92 Jan-93
FIGURE 3-11
1992-1995 Dissolved Oxygen
Cycle in Surface and Bottom
Waters in Stellwagen Basin
(Error bars represent +-/- one standard
deviation.)
FIGURE 3-12
Rate of Decline of Dissolved
Oxygen Concentrations in
Bottom Waters in the Nearfield.
(Error bars represent +-/- one standard
deviation.)
Dissolved Oxygen (mg/L)
Apr-93 Jul-93. Oct-93. Jan-94 = Apr-94— Jul-94 Oct-94 Jan-95— Apr-95
11
Jul-95 Oct-95
13
12
10
Mj
oupe
1992
1993
1994
1995
N
° tr Re
iN
9 :
BR
RO
t il 1993
° I
1995
7+— Year Slope
(mg/L/day)
1992 -0.024 1994
1993 -0.025
g{—_|_1994 -0.031
1995 -0.027 il
Average -0.027
T
5
Jun Jul Aug Sep Oct
11
10
32 / OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
with plenty of daylight. Algal growth rates were intensely stimulated by the July upwelling
event, but too briefly to increase the biomass appreciably. Water column respiration was
uniformly distributed during the unstratified period. During stratification, the upper layer
experienced higher rates of respiration, while the bottom layer respiration rates were ten
times lower. The lower rate of bottom water respiration appears to be related to a reduction
in the transfer of organic matter into the colder, bottom layer during the period of stratifica-
tion.
Marine Mammal/Sea Turtle Observations
A number of whales, dolphins, and harbor seals were sighted during the nearfield surveys.
All of the whale sightings occurred during the summer surveys. During the late July sur-
vey, three Fin whales, 11 Minke whales, and three unidentified whales were observed. One
Fin whale and one unidentified whale were sighted during the early August survey. Two
dolphins were observed during the late September survey. One harbor seal was observed
during each of the surveys in late March, mid May, early July, and early December. No sea
turtles were sighted during any of the surveys.
MWRA : OUTFALL MONITORING OVERVIEW REPORT: 1995 / 33
4.0 Benthic Studies
4.1 Benthic Issues
4.1.1 Nutrients
The concern regarding impact of nutrients on benthic sediments in the area surrounding the
outfall, is that eutrophication, as discussed in the Water Column Monitoring section, might
lead to hypoxia (low oxygen) in the bottom water overlying the seafloor and, consequently,
decreased oxygen within the sediments.
A normal healthy benthic faunal community depends upon well-oxygenated overlying water
to deliver the oxygen necessary for benthic respiration and metabolism. The burrowing and
other activities of the animals assist the penetration of the oxygenated water down into the
sediments, Generally, the healthier the community, with larger and more active animals
present, the deeper the penetration of oxygen into the sediment. Thus, the depth of oxygen
penetration in soft sediments is monitored by MWRA as a measure of environmental health
with respect to sediment oxygen supply and demand.
4.1.2 Toxic Contaminants
Many toxic substances attach to solids, or in the case of metals, may precipitate out of the
water column, so are of concern when monitoring the health of the sediments. The solids
settle to the bottom, and the contaminants associated with the solids may concentrate, par-
ticularly in muddy areas of the bottom where sediments accumulate (sediment deposition
areas). Toxic contaminant concentrations in sediments are monitored by MWRA to assess
the validity of the prediction that discharge of wastewater from the outfall will not lead to
toxic contamination of the sea floor.
4.1.3 Solids and Organic Material
Solids of concern are tiny particles (mud, sand, organic debris) that might be present in the
effluent discharged at the outfall. A potential impact of solid particles on the benthic habi-
tat is smothering caused by particulate deposition. Such an impact could occur if the rate
of deposition became so great that benthic organisms could not maintain contact with the
surface, by burrowing upward, where oxygenated water is available. The problem would
be even greater if the settling solids consist of organic material that consumes oxygen.
4.2 Monitoring Program Design
The benthic monitoring program is designed to provide qualitative and quantitative descrip-
tions of the benthic environments of Boston Harbor and Massachusetts and Cape Cod Bays.
The goals of the benthic program are twofold. The first objective is to document the recov-
ety of benthic conditions in Boston Harbor following the cessation of sludge discharge and
improvements in Combined Sewer Overflow (CSO) treatment and discharge. Comparison of
benthic parameters measured before and after termination of sludge disposal into the har-
bor has provided valuable information on bottom sediment response and benthic ecosystem
recovery. Further improvement in sediment quality in Boston Harbor should be seen after
the transfer of sewage from the existing Deer Island outfall to the new Massachusetts Bay
outfall in 1998.
I The depth of oxygen penetration,
or depth to the redox potential
discontinuity (RPD), is the loca-
tion where the sediments change
from oxic (having oxygen) to
anoxic. The RPD depth can be
accurately measured using a
microelectrode, but more readily
can be estimated (apparent RPD)
by visual examination of sedi-
ment cores or, more reliably, sedi-
ment profile images. The appear-
ance of the oxygenated (aerobic)
near-surface layer is light-col-
ored; the deeper anaerobic (hav-
ing no oxygen) layer is generally
full of sulphides and looks dark
blue or black.
FIGURE 4-1
Benthic Nutrient Flux
Sampling Locations
FIGURE 4-2
Boston Harbor Benthic
Sampling and Sediment
Profile Imaging Stations
ans
ora
ans
704s" 0°40" os
The second objective is to collect background data on
physical, chemical, and biological processes in the benthic
environment near the outfall location in Massachusetts
Bay. These data are essential to assessing potential
impacts of the discharged effluent on the surrounding ben-
thic ecosystem.
The benthic monitoring program uses a different defini-
tion of nearfield from that used by the water column
monitoring program. For the water quality program the
nearfield is a rectangle with sides 5 km (3 miles) from
the outfall, and farfield stations are those outside that
rectangle. The benthic program originally followed a sim-
ilar convention but with greater sophistication of its spa-
tial analyses now discriminates between three areas of
the Bay: the nearfield is 0-2 km from the outfall, the
midfield is 2-7 km, and the farfield is greater than 7 km.
This convention was not strictly followed in the 1992-1995
surveys, but was included in the 1996 program. The
nearfield definition coincides with the area that will be impacted according to the SEIS.
The midfield is farther from the
outfall and should not show impacts. The station design
for the biological program provides the minimum number (12) of samples, necessary for
detection of change (Coats, 1995), in each area. There are 8 stations (2 with triplicate
samples = 12 samples) in the nearfield, 15 stations (4 with triplicate samples = 23 sam-
ples) inthe midfield, and 8 stations (all with triplicate samples = 24 samples) in the
farfield. Three of the midfield stations, FF10, FF12, and FF13 retain their prior farfield
station names to eliminate the necessity of assigning totally new numbers to them; there
Key: 4
+ Traditional Stations
© Sediment Profile
°
‘maging Stations.
are already station designations for MF10, MF12,
and NF13.
«am Three types of benthic surveys are performed:
nutrient flux surveys, soft-bottom surveys, and
hard-bottom video surveys. Each of the three sur-
vey types is described below.
ad 4.2.1 Nutrient Flux Surveys
Nutrient flux surveys are designed to measure
nutrient interactions between sediments and the
water column in Boston Harbor and Massachusetts
Bay. The nutrient flux surveys take place five
times per year at seven sampling locations; in
1995, an eighth station (Quincy Bay), was sampled
during the last three surveys (Figure 4-1). Using a
sediment coring technique, vertical columns of
sediment are removed and brought to the surface
42°18"
+ a2i6
intact. For each sediment core, measurements are
made of sediment oxygen demand and oxygena-
tion, sediment nutrient flux, and sediment pore
MWRA - OUTFALL MONITORING REPORT: 1995 / 88
water (water contained between sediment particles) nutri-
ents. Analysis of these parameters provides information
required to assess nutrient and oxygen exchanges
between sediments and the water column, as well as the
potential for sediment and water column oxygen impacts.
4.2.2 Soft-Bottom Surveys
Soft-bottom benthic surveys are the core of the benthic
monitoring program because they focus on muddy deposi-
tional areas which tend to accumulate suspended materi-
al. The surveys are designed to assess sediment quality
and the status of the benthic communities living in
Boston Harbor and Massachusetts and Cape Cod Bays.
The soft-bottom surveys use a combination of sediment
grab samples and sediment profile images from specified
locations to examine the benthic infauna, and physical
and chemical sediment parameters, including the apparent
redox potential discontinuity (RPD) depth. The four sam-
pling regions are Boston Harbor, the nearfield close to the
outfall, the midfield, and the farfield area ranging east to
Gloucester and southeast into Cape Cod Bay.
The Boston Harbor soft-bottom surveys, designed to mea-
Fi T
MFS
1 4 a
———s .
"
Frio mes MFA .
+ a
MET a
ea
+ “
MF21 a“
i + — —) 42°24"
MFB wes Ko \
/ NFB NF23
MF10
* Future Outfall
+ “7
+ FFI2 Mri2 1 NFI3 Pee
fos Pd
{ NEW
+ +
a \ NPIS" AFIT * yrza
mrzp MFI6 \
\,
\ * nrg
nai aT ee
7 > Nearfleld/Mldfleld ~-—-———-— - aya
Boundary
° N
° Mrz )
re) <P
<— * ME2
J] ane
+ FFIS
1 i Il
ase mse so aw
FIGURE 4-3
Nearfield and Midfield Soft
sure long-term recovery in benthic communities and sedimentary conditions at a variety of
locations, are performed twice annually. Grab samples are collected during both surveys at
eight stations. Sediment profile images are collected from the same eight stations, as well
as an additional 52 stations during the summer survey (Figure 4-2).
Massachusetts Bay soft-bottom surveys in the outfall nearfield
and midfield areas provide baseline data on the sedimentary
environment, contaminant concentrations, and benthic infau-
nal communities that can be used as a benchmark to evaluate
the effects of sewage disposal from the future outfall when it
becomes operational. Surveys of the nearfield and midfield
benthos are performed once per year with sampling at eight
nearfield (less than 2 km from the diffuser) and fifteen mid-
field (between 2 km and 7 km from the outfall) stations
(Figure 4-3). In 1995, sediment profile images were collected
from all eight nearfield and twelve midfield stations.
Farfield soft-bottom sediments are also sampled once per
year at eleven locations (Figure 4-4) throughout
Massachusetts and Cape Cod Bays. Eight farfield stations
are outside of the 7 km midfield boundary; three are in the
midfield. The farfield baseline is used as reference for the
nearfield and midfield stations and as true monitoring sta-
tions in the unlikely event that the effects of the sewage dis-
charge extend farther than expected.
Bottom Stations
FIGURE 4-4
Soft Bottom Benthic
Stations in the Bays
+ Near/midfield Stations
© Farfield Stations
ao
4200"
ras?
36 / OUTFALL MONITORING REPORT: 1995 - MWRA
4.2.5 Hard-Bottom Surveys
A nearfield hard-bottom video survey is performed annually to supplement the nearfield
soft-bottom surveys. The hard-bottom survey provides visual information on the benthic
habitat and organisms occupying rock and cobble areas near the future outfall. The con-
cern is that the organisms may be particularly susceptible to the smothering which could
occur during the stratified period when low currents may allow particles to accumulate on
the rocks. The hard-bottom survey is performed using a remotely operated vehicle (ROV)
equipped with a color video camera and a 35-mm camera. These surveys permit assess-
ment of topography and substrata, populations of attached and mobile marine organisms,
and other evidence of biological activity. Each survey is performed along pre-specified tran-
sects to permit detection of year-to-year changes. In 1995, six hard-bottom transects were
surveyed (Figure 4-5).
Both video and still photographs are valuable for establishing baseline data of the drumlin
areas near the outfall. The still photographs are used to show finer details of the structure
of benthic communities inhabiting hardbottom areas in the vicinity of the new sewage out-
fall than can be discerned from a review of the video tapes. The two techniques are com-
plementary: the video survey provides greater areal coverage, whereas the still photographs
provide more accurate assessments of the benthic communities inhabiting these areas.
FIGURE 4-5 4.8 Threshold Comparison
Nearfield Hard-Bottom Benthic
Survey Transects Trigger parameters and their thresholds for the benthic sediments and 1995 monitoring
results are summarized in Table 41. The basis of the
70°49'W 70°48 W 70°47" W 70°46 W trigger parameters and threshold values, as well as
2°24'N
progress in comparing monitoring results to threshold
au
=) 7 values are discussed below.
BOS \
RESS
Z| 130°
Benthic Community Structure.
42°24'N
TT C |
Lo Benthic community thresholds are intended to verify
2 the prediction in the SEIS that there will not be appre-
SSN IY ciable change in the benthos outside the 2 km outfall
“oO ae = boundary. The trigger level to describe communi
y. the triggel ty
change is under development, and MWRA has been
considering the utility of various measures of benthic
species composition, diversity, and relative abundance.
<q The trigger level developed will involve comparison of
NS a measure of the community in the midfield with its
baseline values.
‘
2°23'N
42°23'N
women __ Diversity values using the 1995 data are shown on Table
ow 4-2. Three measures of species diversity, Shannon-
Wiener diversity (H’), evenness (J’), and Hurlbert rar-
CO efaction are given. These results show that, by most cri-
teria, FF13 (just east of Point Allerton, i.e., Hull) is the
—— least diverse station and FF10 (east of Nahant) is the
1 0 1 most diverse of the midfield stations.
2°22'N
MWRA - OUTFALL MONITORING REPORT: 1995 / 37
Parameter
Community Structure
(Diversity, Species
Composition, and
Species Abundance)
in outfall midfield area
TABLE 4-1
Benthic Thresholds Compared to 1995 Monitoring Results
Caution Level
Species diversity, composition,
and relative abundance patterns
Measured in the midfield appre-
ciably depart from those mea-
sured during the baseline moni-
toring period, after factoring out
the effect of storms on sediment
texture, Specific diversity thresh-
old values are being developed.
Warning Level
None.
1995 Results
Shannon-Wiener Diversity Index
Midfield mean = 2.71
(Range 2.18 - 3.13)
{See also Table 4-2)
Depth of Oxygenated
Sediments [Redox
Potential
Discontinuity (RPD)
Depth] in outfall
nearfield area.
RPD depth declines by half.
The threshold value is under
development.
None.
Nearfield mean = 3.5 cm
(Range 1.8 - >6.2 cm)
Toxic Contaminant
Concentrations in
outfall nearfield area.
Nearfield mean toxic contami-
nant concentrations greater than
90% of EPA sediment criteria.
Nearfield mean toxic contaminant concentra-
tions greater than EPA sediment criteria or the
NOAA Effects Range Median (ER-M) value.
Examples: NOAA ER-M values:
PCBs = 180 ng/g
Mercury = 0.71 pug/g
Example Results:
PCBs:
Geometric Mean = 4 ng/g
Range = 1.1 - 53 ng/g
Mercury:
Geometric mean = 0.16 g/g
(See also Table 4-3)
Trigger Parameter
TABLE 4-2
1995 Diversity Data for the Midfield Stations (2-7 km from the outfall)
Caution Level
Warning Level
Range and Mean (x )
Shannon-Wiener H’ Appreciable change No criteria 2.18 8) 3's {FF10)
K =2.
Evenness J” Appreciable change No criteria 0.52 (FF13) - 0.69 (MF4)
x = 0.64
Hurlbert Rarefaction Appreciable change No criteria 12.97 (FF13) - 20.63 (FF10)
# spp./50 ind. x= 16.48
Hurlbert Rarefaction Appreciable change No criteria 18.20 (MF8) + 30.11 (FF10)
# spp./100 ind. X = 23.12
Hurlbert Rarefaction Appreciable change No criteria 34,43 (MF8) - 58.63 (FF10)
# spp./500 ind. x= 44.07
38 / OUTFALL MONITORING REPORT: 1995 - MWRA
Establishment of the final threshold values and comparison of threshold values to post-dis-
charge monitoring results will need careful consideration. A decrease in species diversity or
a change in species composition is not necessarily a measure of "degradation". While a
moderate organic enrichment of the sediment may cause the disappearance of some sensi-
tive species, the overall effect may not necessarily be detrimental if increased biomass is
available as a food source for bottom fishes. Also, the existing data from previous years
shows that dramatic changes in diversity or other community parameters can occur in the
natural system from year to year even without any discharge effect.
Redox Potential Discontinuity
The Redox Potential Discontinuity (RPD) depth is the location where the sediment changes
from oxic, or oxygenated, to anoxic, or depleted of oxygen. The RPD depth provides an
important measure of the overall health of the benthic infauna habitat. In the absence of a
state standard for the RPD depth, a threshold was developed to measure and evaluate sig-
nificant changes in RPD depth which could provide an indication of adverse impacts from
the deposition of discharged organic material. The RPD depth threshold is applicable to the
nearfield area.
The 1995 RPD depth results indicate that, in general, sediments appear to be well-oxygenat-
ed and are healthy with respect to the depth of oxygenated sediments. The 1995 RPD
depth data showed a range of 1.8 cm to greater than 6.2 cm (sediments oxygenated at max-
imum depth reached), with a mean value of 3.5 cm. Comparison of the results from 1995
and previous years indicates that RPD depth values are similar and have not changed signif-
icantly.
Toxic Contaminants
Thresholds for toxic contaminants in sediments are established to be protective of benthic
organisms. Monitoring results from the post-discharge operation period will be compared to
sediment threshold values to verify predictions of potential toxic contaminant concentration
in sediments and to assure that adverse toxic effects to benthic organisms do not occur.
Specific threshold values are based on EPA sediment criteria and NOAA ER-M values. Draft
EPA sediment criteria exist for five organic contaminants: acenaphthene, fluoranthene,
phenanthrene, dieldrin, and endrin. NOAA ER-M values are available for a variety of organ-
ic and metal contaminants.
Comparison of 1995 sediment concentration data to relevant thresholds is provided on
Table 4-3. The trigger parameter is expressed as a sediment concentration averaged over
the nearfield stations (less than 2 km from the future outfall). As in previous years,
organic contaminant concentrations were generally low and did not exceed any of the
thresholds; even station NF24 with a TOC concentration of 2.77% had organic compound
concentrations well under EPA sediment criteria that assumed 1% TOC. Metal concentra-
tions were similar to those measured in previous years. The nearfield mean concentra-
tions for all heavy metals were below the warning level. One individual nearfield station,
however, had a mercury concentration of 1.69 jig/g (NF24, Fig 4-3), exceeding the warn-
ing level of 0.71 g/g. Outside the nearfield, station MF21 also had elevated mercury
(0.68 g/g). Elevated mercury was also apparent in the 1994 data and reflects the very
highly depositional nature of those sites (data prior to 1995 are unavailable because these
stations were added in 1994).
MWRA - OUTFALL MONITORING REPORT: 1995 / 39
TABLE 4-3
Toxic Contaminant Thresholds and 1995 Data for the Eight Nearfield Stations (0-2 km from the outfall)
Trigger Parameter Caution Level: Warning Level: Range and Mean (x), and
(units) 90% EPA criterion’ EPA criterion’ or (Geometrical Mean)
(NOAA ER-M) level
Organic Contaminants
Total PAH - (44,792) 78 (NF17) - 10,903 (NF24)
(ng/g) X = 2,380; (870)
Acenaphthene 1170 1300 ND (2 stations) - 41(NF24)
(ng/g) (600) X= 11; (NAY
Fluoranthene 5580 6200 8.8 (NF17) - 1050 (NF24)
(ng/g) (5100) X = 245; (96)
Phenanthrene 1620 1800 4 (NF17) - 570 (NF24)
{ng/g) (1500) 3 = 132; (49)
Total PCB _ (180) 1.1 (NF43, NF17, NF23) - 53 (NF24)
(ng/g) ¥ = 10; (4)
Total Chlordane - (6) ND (7 stations) - 1.09 (NF24)
(ng/g) X = 0.136; (NA)*
Total Dieldrin 99 110 ND*(8 stations)
(ng/g) (8) x =0; (NA)
Endrin 87.8 42. NDB (8 stations)
(ng/g) X =0; (NA)
Total DDT - (46.1) ND (3 stations) - 11.21 (NF24)
(ng/g) X = 2.2; (NA)!
Trace Metal Contaminants
Cadmium = (9.6) 0.05 (NF13) - 0.46 (NF24)
(ug/g) X = 0.12; (0.09)
Chromium - (370) 28.2 (NF23) - 177.0 (NF24)
(ug/g) X = 53.5; (41.7)
Copper — (270) 3.41 (NF23) - 54.25 (NF24)
(ug/9) XK = 16.60; (11.22)
Lead ~_ (218) 25.8 (NF23) - 92.9 (NF24)
(ug/g) XK = 44.9; (41.3)
Mercury - {0.71) 0.029 (NF28) - 1.69 (NF24)
(9/9) X = 0.36; (0.16)
Nickel _ (51.6) 7.2 (NF17) - 31.8 (NF24}
(ug/g) ¥ = 13,8; (12.3)
Silver = (3.70) 0.08 (NF17) - 1.1 (NF24)
(ug/a) K =0.3; (0.2)
Zinc - (410) 25.2 (NF17) - 131.5 (NF24)
(ug/g) X = 49.5; (42.7)
* Values for EPA sediment quality criteria assume 1% organic carbon. Hull and Suter (1995)
2 NOAA ER-M levels taken from Long ef al. (1995)
3 From Long and Morgan (1992)
* NA = Not Available. Geometric means cannot be calculated for data sets that include zeroes,
5 Detection levels: Dieldrin = 0.022 ng/g; Endrin = 0.0061 ng/g.
40 / OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
Figure 4-6
Distribution of Amphipod Tube
Mats in Boston Harbor from
1991 Through 1995.
Maps courtesy of Brian Howes and Tony
Millham, Woods Hole Oceanographic
Institution,
M@ Ampelisca abdita, and A. vado-
rum are pollution sensitive,
deposit-feeding amphipod crus-
taceans capable of building tube
mats, Tube mats are often sev-
eral centimeters thick, and may
reach densities of over 100,000
individuals per square meter.
The widespread colonization of
Boston Harbor sediments by
this infaunal complex has
increased both the degree of sed-
iment oxidation and rates of
sediment/water column
exchange through bioturbation
and burrow ventilation.
4.4 Monitoring Results
Data from the benthic study monitoring
program can be broadly categorized as
physical, biological and chemical study
results, The physical nature of the bottom
sediments define the benthic habitat.
Benthic organisms that inhabit muddy,
sandy, or hard bottom gravel substrates are
significantly different.
In Boston Harbor, most surficial sediments
consist of mud (silt + clay) rather than
sand. In channel and shallow areas near
islands, however, fine sediments are
washed away by currents and waves, and
sandy sediments predominate.
In Massachusetts Bay, there is an overall
trend toward finer sediments offshore.
However, in western Massachusetts Bay
near the outfall, the bottom characteristics
are highly variable, ranging from erosional
hard bottom (cobbles, gravel, and rock) to
soft bottom consisting of sands and muds.
These various bottom types are widely
interspersed with patch sizes on the order
of hundreds of meters. Furthermore, the
sediment profile camera has revealed that the sediment spatial pattern between the hard-
bottom environment nearest the outfall and the fine sedimentary depositional area further
west is temporally dynamic, showing significant movement and redeposition of sediments
following major storms. In contrast, the benthic environment in Cape Cod Bay is relatively
homogeneous and stable over time.
Percent of stations
Ey Us 393
‘Years Sampled
Fz Mat al least patchy,
Bi Full armphipou mat pasnyia
im) Mal patchy or few amphipods present
4.4.1 Biological Study Results
Surveys of benthic biological communities are used by MWRA to evaluate the overall
ecological health and environmental quality of the Massachusetts Bay and Cape Cod
Bay systems.
4.4.1.1 Boston Harbor
One of the more intriguing findings of the Boston Harbor surveys has been widespread
development of dense tube mats of the opportunistic, yet pollution-sensitive amphipod
Ampelisca abdita. The ampeliscid tube mats have contributed to the appearance of other
amphipods as well. Since 1991, there has been a steady increase in the area covered by
amphipod tube mats in the harbor (Figure 4-6). Prior to the elimination of sludge dis-
charge, less than 20 percent of stations surveyed showed the presence of amphipod tube
mats. By 1995, more than 60 percent of the monitoring stations showed well-developed
MWRA + OUTFALL MONITORING REPORT: 1995 / 41
tube mats. This phenomenon is likely related
to improving sediment and water quality fol-
lowing sludge discharge abatement and possibly
to the October 1991 storm which dramatically
altered the sediment structure in the Harbor.
Ampelisca colonization has led to increased
sediment oxygenation and improved sediment
quality.
Although the benthic infaunal communities in
the harbor differ from station to station, they
have historically fallen into two groups.
Northern stations, closest to the outfalls, have
been characterized by opportunistic, highly vari-
able assemblages that are able to tolerate high
organic sediment loading. Southern stations
have generally exhibited more consistent and
predictable assemblages dominated by organisms
that require better sediment quality (eg., tube-
dwelling amphipods). Sludge abatement has
changed the infauna at some northern stations
so that they have become progressively more
similar to the southern stations.
Infauna species richness increased harborwide
since 1991, especially at the northern stations.
Several species that were previously rare or
absent are increasing significantly in numbers (e.g., the polychaete worm, Chaetozone vivip-
ara, and amphipods belonging to the genus Corophium). The change in species richness is
probably due to habitat modifications caused by Ampelisca, which in turn may be related to
the sludge abatement.
4.4.1.2 Massachusetts Bay
Benthic biology surveys in Massachusetts Bay provide baseline data that can be used as a
benchmark to evaluate the potential effects of sewage disposal from the future outfall when
it becomes operational.
0
e MILES
30
Ox
T) aan
2
e a
a
e e™ a“ | one
" 3 @ °°
25
mY 28 Future
/ Outtall
® 21 * e@, Pam
a
7 i «& a
KEY: e
23 9
mi e' @.,
e 18 - 20 species/100 Individuals 2 mm
e 24 - 28 spectes/100 individuals 2 \
124 - 26 species/100 Individuals \ e.
27-30 speci f ~ “
@ [27-30 spoctesst00 individuals weortamen -
oO v 7
° y
e
2
e .
2
*s
i | 1 1
HPS We52 TOS" Tae"
Figure 4-7
Nearfield and Midfield Soft-bottom Community
The results of the 1995 Massachusetts and Cape Cod Bays benthic surveys were similar to
those seen in the previous year's baseline monitoring data. The structure of the benthic
communities in the nearfield and midfield was largely determined by sediment grain-size.
In finer-grained sediments, some marine worm species (capitellid and spionid poly-
chaetes) were most abundant, while in sandier sediments, other worm species (syllid and
paraonid polychaetes), amphipod crustaceans, and certain oligochaetes predominated.
These basic community structures have been observed in the area since inception of this
program, with changes at individual stations reflecting the shifting of sediments at indi-
vidual stations by storm-generated currents.
Soft-Bottom Benthic Community
Diversities at Nearfield and
Midfield Stations.
Wf Sediment carbon and nutrient
cycling data are sensitive indica-
tors of the changing ecological
health of Boston Harbor and are
key elements for evaluating the
oxygen balance of
Massachusetts Bay bottom
waters. Results from studies of
the sediment-infauna habitat
within Boston Harbor provide an
example of the complex response
of marine systems to changes in
organic matter loading rates and
the need for direct measurement
of benthic processes.
-] soe
42 / OUTFALL MONITORING REPORT: 1995 - MWRA
Wi Benthic Community Diversity is
often used to evaluate environ-
mental change. Examples of
changes in community diversity
include changes in the relative
abundance of various species, or
changes in the numbers and
kinds of species that live in a
particular habitat.
lf Diversity of marine organisms
is often used as a measure of
environmental health; typically,
the more diverse the assemblage
(ie., the more species present,
taking into account the number
of animals collected) the healthi-
er the community. One way to
look at diversity is to calculate
how many species would have
been collected if a sample had
only contained a specific num-
ber of organisms. This tech-
nique, known as rarefaction,
allows samples differing in size
to be compared.
The results of the soft-bottom surveys suggest that biological variability in the vicinity of
the future outfall is greater than expected from pre-baseline monitoring. For example,
there was an appreciable change in the dominant spionid polychaete species present in
1995 compared to 1992-1994. In 1992-1994, Spio limicola dominated, but in 1995 the
dominant species was Prionospio steenstrupi, last found to be abundant in the 1987-1988
reconnaissance surveys.
Densities of benthic infauna in Massachusetts Bay are often high, but do not generally reflect
stressed environments like those existing in parts of Boston Harbor. The dominant species in
the bay are not typically associated with deteriorated benthic habitats but are species that
often are found in areas with suspended organically-enriched material in the water column.
Certain dominant taxa such as spionid polychaetes are able to clear organic-rich material
from the water column, and use it for food and material for tube construction.
In 1995, faunal diversities at the nearfield and midfield stations were similar (Figure 4-
7). The number of species in the nearfield ranged from 19 to 29 species per 100 organ-
isms, whereas in the midfield, diversity ranged from 18 to 30 species per 100 organisms
(Table 4-2).
Farfield Soft-Bottom Communities.
Benthic community structure in the farfield was mostly influenced by water depth and also
by location (Massachusetts Bay versus Cape Cod Bay). The most common species in the
farfield were generally similar to those in the nearfield. The two Cape Cod Bay stations dif-
fered the most from the Massachusetts Bay stations, probably because of a different sedi-
mentary environment. The spionid polychaete Prionospio steenstrupi ranked first at all
Massachusetts Bay stations, but was not among the most dominant species at the Cape Cod
Bay stations where cossurid polychaetes dominated.
Diversity was basically similar to that of the nearfield and midfield, ranging from 16 to 26
species per 100 organisms. Species diversity, species composition, and infaunal density all
exhibit large swings from year to year, as they do in the nearfield. These variations proba-
bly reflect changes in area-wide environmental conditions that in turn influence the timing
and success of larval settlement of benthic organisms. However, faunal assemblage patterns
in the farfield are more consistent than in the nearfield so that sampling in the farfield will
help distinguish changes due to natural processes from those caused by anthropogenic ones
related to the operation of the outfall. Similarities between the benthic community at mid-
field stations and a farfield station near Gloucester Harbor indicate that the Gloucester sta-
tion can serve as a good qualitative reference site for benthic communities in the vicinity of
the future outfall.
Nearfield and Midfield Hard-Bottom Communities
The complex topography in the hard-bottom areas in western Massachusetts Bay has a sub-
stantial influence on epibenthic communities. These communities are primarily determined
by depth, with red algae dominating the shallower drumlin tops (about 70 feet deep) and
macroinvertebrates dominating the deeper bottoms. Location on the drumlins, depth, bot-
tom type, and habitat relief all appear to play a role in determining the structure of benthic
communities inhabiting hard-bottom areas. Some species show strong preferences for spe-
cific habitats, while others are broadly distributed. Some areas are homogeneous in terms
of bottom type and the fauna inhabiting them, while others exhibit more patchiness.
MWRA + OUTFALL MONITORING REPORT: 1995 / 43
4.4.2 Sediment Chemistry Results
The MWRA benthic surveys have obtained data necessary to evaluate the sediment quality
and related habitat quality conditions and factors in Boston Harbor and Massachusetts and
Cape Cod Bays.
4.4.2.1 Boston Harbor
The 1995 study results indicate that sediment quality in Boston Harbor is improving due to
the breakdown of the organic matter that had settled on the harbor bottom during sludge
discharge, which ended in December 1991. While sludge was being discharged, the benthic
community was apparently overwhelmed by the amount of settling organic material. When
this practice stopped, the benthic community began to degrade the material that had accu-
mulated over the years. Rates of the organic matter breakdown process, or remineraliza-
tion, were more than twice as high in 1995 than reported in any previous monitoring peri-
od. The remineralization rate increase is likely due to the expansion of Ampelisca popula-
tions, as discussed above.
The increased remineralization rate has important implications for sediment and water qual-
ity in Boston Harbor. Remineralization of organic matter containing nitrogen has resulted in
an increased flux of nutrients from sediments into the water column. The remineralization
process involves respiration, a DO consumption process. As a result, sediment respiration
has an important influence on sediment and water column DO in Boston Harbor. Even
though the increased rate of remineralization is improving Boston Harbor sediment quality,
organic carbon concentrations remain relatively high and it will likely take several years for
natural levels to return.
4.4.2.2 Massachusetts Bay
Dissolved Oxygen/Nutrients
In 1995, rates of sediment oxygen uptake and nutrient remineralization in Massachusetts
Bay were comparable to those measured in previous years, in contrast to the changes that
have occurred in the Harbor. The sediments at all stations were relatively well oxidized
with relatively high RPD values and undetectable dissolved sulfide within the sediment
porewaters, Rates of oxygen uptake were low, consistent with measured low rates of nutri-
ent release and porewater nutrient pools. The stability of these measures indicates that
they will be sensitive tools for detecting relatively small changes in carbon enrichment.
The Massachusetts Bay benthic environment plays less of a role in contributing to nutrient
flux and DO depletion than it does in Boston Harbor. The greater water depth in
Massachusetts Bay allows more remineralization to take place within the water column
before particles reach the benthos, and stratification tends to isolate the benthos from the
upper water column. Bottom waters may be affected by the benthos during periods of
stratification.
Toxic Contaminants
Organic constituents in the sediments collected in 1995 (Table 4-3) are similar qualitatively
and quantitatively to those from prior years. Concentrations of organic constituents are
generally low and in no case exceed any relevant environmental standard.
Mi Sediment quality guidelines are
useful screening tools to evalu-
ate potential impacts to sedi-
ment-dwelling organisms, The
National Oceanographic and
Atmospheric Administration
(NOAA) has developed effects-
based guidelines based on a
weight of evidence from many
studies. Chemical concentra
tions below the NOAA “Effects
Range-Low” (ER-L) values are
rarely associated with toxic
effects, whereas chemical con-
centrations above the NOAA
“Bffects Range Median” (ER-M)
values often are associated with
toxic effects.
44 / OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
Sediment metal concentrations in Massachusetts and Cape Cod Bays in 1995 (Table 4-3)
were also similar to those measured in previous years. These metal concentrations are
generally below NOAA ER-M values. The existing effluent metal data, and ambient sedi-
ment and water quality data, indicate that metal ER-Ms are unlikely to be exceeded after
outfall relocation, even with the effluent at the existing primary treatment level. Possible
exceptions to this may occur in localized areas if a large accumulation of organic matter
results in anoxic conditions near the sediment-water interface. Under those conditions, pre-
cipitation of insoluble metal sulfides could enhance sediment metal concentrations.
However, since sulfide-bound metals have been demonstrated to be nontoxic, there would
not be an increase in sediment toxicity even if such metal precipitation were to occur. Also,
the impending treatment plant upgrade from primary to secondary treatment is expected to
result in a decrease in effluent metal concentrations, making an adverse increase in sedi-
ment metal concentrations even less likely.
MWRA + OUTFALL MONITORING REPORT: 1995 / 45
5.0 Fish and Shellfish
5.1 Fish and Shellfish Issues
The impending relocation of the outfall has raised questions concerning the effects of the
effluent on water quality and marine life. Toxic contaminants in the effluent have the
potential to cause a variety of problems throughout the food chain. Because many toxic
contaminants adhere to particles, toxic impacts on marine animals are likely to primarily @ Fish and Shellfish Action Levels.
affect bottom-dwelling organisms and the animals that feed on them, such as flounder and The U.S. Food and Drug
lobster, Shellfish, such as mussels and clams, that feed by filtering suspended matter from Administration (FDA) has estab-
large quantities of water are also potentially vulnerable to toxic contaminants. Exposure of lished action levels for toxic or
flounder to toxic contaminants may result in fin rot and other diseases. Consumption of deleterious substances inhuman
contaminated organisms results in exposure of predators through the food chain including food and animal feed. Action lev-
ultimately human consumers of fish and shellfish. els represent limits at or above
which FDA may take action to
5.2 Monitoring Program Design remove products form the mar-
ket, For example, the FDA legal
limit for contaminants in fish
and shellfish is 2.0 ppm for total
The fish and shellfish monitoring program addresses potential risks to human health and
the environment arising from contamination of ecologically significant and economically
important fish and shellfish stocks. The primary goals of this monitoring program are (1) to
evaluate the health of these marine resources in terms of disease, and (2) to evaluate organ- PCBs and 1.0 ppm for mereury.
ic and inorganic contaminant concentrations in the organs and edible tissues of these organ-
isms. Bioaccumulation data are collected from flounder, lobster, and mussel populations in
Boston Harbor, Massachusetts Bay, and Cape Cod Bay. Comparison of the data between FIGURE 5-1
stations and between pre- and post-discharge periods will allow evaluation of spatial and Sampling Stations for Winter
temporal trends in the fisheries. In addition, the biomonitoring programs will provide base- Flounder, Lobster and Mussels
line data that may be used to assess the potential during 1995.
environmental impact of the effluent discharge on Y
STATIONS: N
Massachusetts Bay, and to evaluate the facility's
compliance with the NPDES effluent discharge per-
mit requirements. The three biomonitoring surveys
are outlined below.
1 — Deer Island Outtall — flounder, lobster, mussels
2— Nantasket Beach — flounder
3 — Broad Sound — flounder
4 — Future Outtall Site — flounder, lobster, mussels
5 — Cape Cod Bay Site — flounder, lobster
4 6—N.E. Aquarium Discovery Site — mussels
The flounder survey is designed to collect sufficient
mature winter flounder to perform general and
histopathological examinations and determine bioac-
cumulation of priority pollutant organics, metals,
and other constituents. Flounder surveys began in
1991 and are performed annually at five locations:
the Deer Island outfall, future outfall site, Cape Cod
Bay site, Broad Sound and Nantasket Beach (Figure
5-1). Fish are collected using a bottom trawl
deployed by a commercial dragger.
Massachusetts
Bay
Similarly, the lobster survey is designed to collect
sufficient mature lobster specimens to provide data
on gross abnormalities and provide sufficient tissue
samples for determination of physiological condition
and body burden of contaminants. Once each year
Cape Cod Bay
46 / OUTFALL MONITORING REPORT: 1995 - MWRA
I The presence of physical
abnormalities in fish and shell-
fish can be a sensitive indicator
of contaminant exposure.
Tumors, lesions, finrot, and
gross deformities are physical
abnormalities that may be
attributable to pollution.
Certain physical abnormalities
such as liver lesions may only be
detected through histopathology,
the study of adverse changes in
tissue structures.
since 1992, lobsters have been collected in 25 to 30 commercial lobster traps deployed at
each of three locations: the Deer Island outfall, future outfall site, and Cape Cod Bay site
(Figure 5-1).
In the mussel bioaccumulation survey, blue mussels are obtained from a clean location,
deployed, and recovered for determination of biological condition and short-term accumula-
tion of contaminants in tissues. Mussels are used as test organisms because of the exten-
sive database available on the rate at which they bioaccumulate contaminants and because
they provide good spatial and temporal experimental control. Each year since 1987, mus-
sels have been deployed in replicate arrays consisting of moored cages in waters near Deer
Island and in Massachusetts Bay near the outfall location (Figure 5-1). Mussel arrays are
deployed using a subsurface and surface buoy system.
5.3 Threshold Comparison
To track the chronic environmental impact of the toxic contaminants, the MWRA measures
the concentrations of a variety of toxic contaminants in flounder, lobster, and mussels from
various locations in Boston Harbor and Massachusetts and Cape Cod Bays. Thresholds for
fish and shellfish, summarized in Table 5-1, are designed to identify any effects on marine
life and potential effects on human consumers of fish and shellfish. The thresholds apply
to the new outfall site.
Of the five monitoring thresholds, three are associated with the potential for edible tissue
(flounder, lobster, mussel) to exceed Warning Levels for mercury, lead, or PCBs. Except for
lead, the Caution Levels are 50% of the U.S. Food and Drug Administration (FDA) Action
Limits; the Warning Levels are 80% of the FDA Action Limits. Lead thresholds are based
on an EPA risk assessment that determined the amount of lead that can be consumed with-
out adverse health effects. The mussel arrays set out at the future outfall site in 1995 were
lost. The flounder and lobster data show that current tissue concentrations are generally an
order of magnitude or more below the Warning and Action Levels (Table 5-1). Values
approaching the Warning or Action Levels should be readily detectable.
Because some toxics tend to concentrate in lipid-rich (fatty) tissues, a lipid-normalized
threshold was established to protect against increases in these contaminants. This thresh-
old is exceeded if bioaccumulative lipophilic contaminants double and remain at that level
for three consecutive years. The three-year specification was chosen to smooth the highly
variable nature of these measurements. The concentrations for 1995 are shown in
Table 5-1. The interim Caution Level was not available for this report but will be included
in the 1996 report. One finding was that the contaminants in flounder liver and lobster
hepatopancreas, which are not considered edible tissue for any of the thresholds, was rela-
tively high in 1995. The validity of the analytical tests was checked and confirmed.
In order to monitor and assess the potential impacts of toxic contaminants on flounder, a
threshold concerning the prevalence of flounder liver CHV was developed which compares
the postdischarge prevalence of CHV with the baseline average prevalence in the Harbor.
The 1995 CHV prevalence at the future outfall site (14%) is below the interim threshold
value (Fig 5-2). The monitoring design will be able to detect changes approaching the
Caution Level.
MWRA - OUTFALL MONITORING REPORT: 1995 / 47
5.4 Monitoring Results
5.4.1 Flounder M Replicates are multiple samples
that are used to increase the
reliability and accuracy of exper-
imental data. Multiple arrays of
mussels are used to increase the
sample population and thereby
reduce the uncertainty in the
results.
The results of the fish and shellfish program have revealed temporal and areal patterns, and
illustrated the variability of the ecosystem. In general, levels of contaminants and the num-
ber of physical abnormalities in the fish and shellfish studied, have decreased over the
study period. Boston Harbor organisms are the most affected by toxic contaminants, while
those in Cape Cod Bay are least affected. The following sections present the 1995 fish and
shellfish monitoring results, along with comparisons to previous data.
In 1995, fifty winter flounder were collected at each of the five monitoring program sites:
Deer Island Flats, the future outfall site, Nantasket Beach, Broad Sound, and eastern Cape
Cod Bay (Figure 5-1). All flounder were examined for physical abnormalities, and
histopathological liver lesions. In addition, the tissue from fifteen of the fifty flounder from
three locations (Deer Island Flats, future outfall site, eastern Cape Cod Bay) was analyzed
for concentrations of organic and inorganic contaminants.
Physical Condition and Histology
The external condition of the collected fish indicated few abnormalities, although fin ero-
sion was seen in fish from all stations. The flounder from the future outfall site and Cape
Cod Bay showed significantly lower levels of fin rot than other stations. The amount of
TABLE 5-1
Fish and Shellfish Thresholds Compared to 1995 Monitoring Results
Parameter Caution Level Warning Level 1995 Resuits
Mercury in fish Annual mean mercury concentration in flounder, lob- | Annual mean mercury concentration in | Flounder - 0.06 ug/g
and shellfish ster, and caged mussel meat greater than 0.5 ug/g | flounder, lobster, and caged mussel Lobster - 0.13 ug/g
from Outfall site | wet weight (50% of the US FDA action level). tissue is greater than 0.8 pg/g wet Mussel - NA’
weight (80% of the US FDA action
level).
PCBs in fish and | Annual mean PCB concentration in flounder, lobster, } Annual mean PCB concentration in Flounder - 0.041 yig/g
shellfish from and caged mussel meat greater than 1 L1g/g wet flounder, lobster, and caged mussel Lobster - 0.015 pg/g
Outfall site weight (50% of the US FDA action level). tissue is greater than 1.6 j1g/g wet Mussel - NA"
weight (80% of the US FDA action
level).
Lead in mussels | Annual mean lead concentration in caged mussel Annual mean lead concentration in Mussel - NA’
at Outtall site meat greater than 2 g/g wet weight. caged mussel tissue is greater than
3 y19/g wet weight.
Lipid-normatized | Lipid-normalized toxic concentrations in flounder, None. Concentrations in ig
toxics in fish and | lobster and caged mussel meat greater than two toxic per gm lipid
shellfish from times the baseline concentrations. Lobster PCBs: 2.9
Outfall site Lobster DDT: 0.4
Flounder PCBs: 11.4
Flounder DDT: 1.4
Liver disease Flounder liver disease (CHV) incidence greater None. Flounder CHV prevalence:
incidence in fish } than in Boston Harbor. The 1991-95 average is 14%
from Outfall site 48%.
' Outfall site mussel cage arrays were lost in 1995.
48 / OUTFALL MONITORING REPORT: 1995 - MWRA
FIGURE 5-2 80 [
Prevalence of CHV near
the Future Outfall Site, et
1991-1995. > OOF
iz) | Caution Level
c
2
o
>
2
a
>
rz
(o)
Year
fin erosion observed throughout is considered low, and is well below that observed in the
late 1980s.
The flounder liver histology results indicated that flounder from all sampling locations expe-
rienced liver lesions. The flounder from Deer Island Flats and Broad Sound exhibited the
greatest prevalence of lesions. The prevalence of one type of liver lesion, centrotubular
hydropic vacuolation (CHV), has been used by MWRA since 1991 as a sensitive indicator of
contaminant exposure in flounder from Boston Harbor and the bays.
Although there is significant regional variability, sampling results indicate that the incidence
of CHV in winter flounder has been decreasing since 1991. The presence of CHV in fish
from the future outfall site has dropped steadily from about 30% of the population in 1992,
to 14% in 1995. Meanwhile, the prevalence of CHV in flounder from Broad Sound has
dropped from more than 75% to about 30% over the same period. In other areas, such as
Cape Cod Bay and Nantasket Beach, the prevalence of CHV has been relatively constant.
Bioaccumulation
In 1995, contaminant concentrations were measured in 15 flounder meat samples, and 15
flounder liver samples from the Deer Island Flats, future outfall site, and East Cape Cod Bay
sampling locations. All samples were analyzed for PCBs, chlorinated pesticides, and mer-
cury. The liver samples were also analyzed for a number of other organic and inorganic
contaminants.
The monitoring results (Figure 5-3) indicate that contaminant concentrations in flounder
meat and liver are generally higher in Boston Harbor near the Deer Island outfall and at the
future outfall site than at the Cape Cod Bay site. Contaminant concentrations at the future
outfall site are generally intermediate between values at Deer Island and the Cape Cod Bay
site. However, several metals in flounder liver (copper, lead, silver, and zinc) were higher at
the future outfall site than at Deer Island in 1995. Two notable features of the 1995 floun-
der liver data when compared to previous years are 1) elevated concentrations of DDT and
PCBs, and 2) reduced chlordane levels. These variations are likely due to a number of com-
plex factors, including the transport and mobility of contaminated sediments and the effects
of exposure of fish to contaminants in sediments and resuspended sediments.
MWRA : OUTFALL MONITORING REPORT: 1995 / 49
5.4.2 Lobster ;
Mercury in Flounder Meat PCB in Flounder Meat
Fifteen northern lobsters were collected as _ 1
from each of three sites (Deer Island ue - i a
Flats, future outfall site, East Cape Cod bu {| &
Boos §
Bay; Figure 5-1) for the 1995 monitor- Eos z
ing program. Muscle and hepatopan- gee é
creas samples were taken from each o}imsly LL a
lobster and analyzed for PCBs, chlori- | Saulonteve'=05ppm __+ °ien Caution eve= 1000p) ow
ted pesticid d : Th
nated pesticides, and mercury. The
hepatopancreas samples were also ana-
lyzed for a number of other organic and Mercury in Lobster Meat PCB in Lobster Meat
inorganic contaminants. >. —_
z Fo
H 2 &
With the exception of one incidence of | 3°" aa
shell erosion at the future outfall site, Boo ; *
no deleterious external conditions were | &* 3”
° °
noted. caution Level = 08 ppm Se Eaton “ Caution Level = 1000 ppb_——S"° ietuon “
Asin previous years, the 1995 mean DI = Deer Istand Outfall NB =Nantasket Beach BS=Broad Sound FOS= Future Outfall Site © CCB = Cape Cod Bay Site
concentrations of organic compounds in FIGURE 5-3
edible tail meat tissue were generally highest at Deer Island Flats and lowest in East Cape PCB and Mercury
Cod Bay. However, PCB concentration levels were similar at Deer Island and the future out- Concentrations in Flounder
fall site (Figure 5-3). In a departure from previous years, the 1995 mean concentrations of and Lobster Meat, 1992-1995.
organic compounds in the hepatopancreas were generally higher at the future outfall site
than at either of the other two sampling locations. The major changes in organic contami-
nant levels in 1995 were: 1) a decrease in chlordane in tail meat, and 2) an increase in
PCBs and pesticides in the hepatopancreas.
Mean mercury concentrations in tail meat were highest at the future outfall site (Figure 5-
3), while mercury concentrations in the hepatopancreas were similar among stations.
The concentrations of other metals in the hepatopancreas were similar at all sampling
locations, although typically a bit lower in East Cape Cod Bay. Silver concentrations in
1995 were markedly higher than in previous years at all sampling locations. For example,
the silver concentration doubled at the future outfall site between 1994 and 1995.
Otherwise, 1995 metal concentrations in the hepatopancreas were generally lower than
those measured previously.
5.4.3 Blue Mussel
A series of mussel bioaccumulation studies has been conducted since 1987 to determine
whether selected contaminants (PCBs, pesticides, PAHs, and metals) bioaccumulate in shell-
fish. Mussels were collected from two relatively clean locations: Gloucester and Sandwich,
MA and deployed in cages in three locations (Figure 5-1): near the present outfall location
at Deer Island Flats; at the future outfall site; and in the inner Harbor (hanging from the
New England Aquarium’s barge, the Discovery). After 60 days, mussels were harvested for
biological and chemical analyses. In 1995, the arrays were successfully retrieved at the
Deer Island Flats and Discovery sites, but not at the future outfall site. The loss of the
future outfall site array was apparently due to entanglement with fishing gear.
50/ OUTFALL MONITORING REPORT: 1995 - MWRA
LMW PAH Concentration ( ppm wet weight)
o7 ° @MWRA Data Overall, study contaminant levels
06 @ NOAA Status and Trends Data at the Boston Harbor stations
(Deer Island and Discovery) have
084 decreased significantly since 1987.
04 For example, as shown in Figure
03 5-4, low molecular weight PAH
“| levels near the Deer Island outfall
02 ° decreased by over a factor of five
at ° ° : between 1987 and 1995. The spa-
3 e i tial distribution of contaminant
° concentrations shows higher levels
1987 1988 1989 1990 {eet 1992 1993 1904 1995 of most contaminants at the
FIGURE 5-4 Discovery site, and lower levels at
Total LMW PAH the Deer Island Flats sampling location. The 1995 predeployment contaminant levels were
Bioaccumulation in Mussels substantially lower than all locations, for all contaminants.
Near Deer Island Discharge,
1987-1995. [Previous to 1995
mussels were analyzed for the
NOAA status and trends list for
PAHs. In 1995, mussels were
analyzed for an extended set of
PAHs, which includes the NOAA
list, but modestly overestimates
the concentrations. See Mitchell
et. al. 1996]
PAH and pesticide (DDT, chlordane, dieldrin) body burdens for all sites were comparable to
1994 levels (Table 5-2). Lead tissue concentrations were somewhat higher at the Discovery
site than at Deer Island in 1995. Mercury concentrations in mussel tissue were low in 1995,
and not appreciably different among sites. The low concentration of mercury at Deer Island
compared to the previous year may indicate the need for further study.
TABLE 5-2
Comparison of Average Body Burdens of Deployed Mussels
for Selected Organic Compounds and Metals
Predeployment Future Discovery | Predeployment Deer Discovery
Parameters Gloucester | Outfall Site Deer Island Average Gloucester Island Average
PAH (ppb wet weight)
LMW PAH 21.2 12.2 43.4 15.8 21.0 68.0 41.2
HMW PAH 31.6 12.2 126 435 21.8 84.2 247.6
Total PAH 52.8 24.4 170 451 42.8 152.1 288.8
Pesticides (ppb wet wt)
Total Chlordane 2 1.8 5.4 5.8 0,79 2.6 44
Total DDT 54 3.8 10 17.2 §.75 9.0 18.4
Polychlorinated Biphenyls
(ppb wet weight)
Total PCB 21.4 17.8 32.2 100 18.7 43.1 88.2
Metals (ppb wet wt)
Mercury 036 0.026 0.042 032 0.013* 0.014 0.014
Lead 172 96 18 1.33 1.212 1.598 1.708
Source: Downey et al., 1995
* predeployment Sandwich, MA
MWRA + OUTFALL MONITORING OVERVIEW REPORT: 1995 / References
References
Butler, E., M. Higgins, J. Chiapella, and W. Sung. 1997. Deer Island Effluent
Characterization Studies: January 1995 — December 1995. MWRA Environmental
Quality Department Technical Report Series. No. 97-3. Massachusetts Water Resources
Authority, Boston, MA. 91 pp.
Cibik, S.J., B.L. Howes, C.D. Taylor, D.M. Anderson, C.S. Davis, and T.C. Loder III. 1996.
1995 Annual water column monitoring report. MWRA Environmental Quality
Department Technical Report Series No. 96-7. Massachusetts Water Resources Authority,
Boston, MA. 241 pp.
Coats, D.A. 1995. 1994 annual soft-bottom benthic monitoring: Massachusetts Bay out-
fall studies. MWRA Environmental Quality Department Technical Report Series No. 95-20.
Massachusetts Water Resources Authority, Boston, MA. 184 pp.
Galya, D.P, J. Bleiler, and K. Hickey. 1996. Outfall monitoring overview report: 1994.
MWRA Environmental Quality Department Technical Report Series No. 96-4.
Massachusetts Water Resources Authority, Boston, MA. 50 pp.
Hilbig, B., J.A. Blake, E. Butler, B. Hecker, D.C. Rhoads, G. Wallace, and LP. Williams. 1997.
Benthic Biology and Sedimentology: 1995 Baseline Conditions in Massachusetts and
Cape Cod Bays. MWRA Environmental Quality Department Technical Report Series
No. 96-5. Massachusetts Water Resources Authority, Boston, MA. 230 pp.
Hilbig, B., J.A. Blake, D.C. Rhoads, and LP. Williams. 1997. Boston Harbor Soft-Bottom
Benthic Monitoring Program: 1995 Results. MWRA Environmental Quality Department
Technical Report No. 96-8. Massachusetts Water Resources Authority, Boston, MA. 94 pp.
Hull, RN. and G.W. Suter. 1995. Toxicological benchmarks for screening contaminants
of potential concern for effects on sediment-associated biota:1994 revision.
Oak Ridge National Laboratory Report ES/ER/TM-95/R1. 28 pp.
Hydroqual. 1995. A Water Quality Model for Massachusetts and Cape Cod Bays:
Calibration of the Bays Entrophication Model (BEM). MWRA Environmental Quality
Department Technical Report Series No. 95-8. Massachusetts Water Resources Authority,
Boston, MA. 402 pp.
Long, E.R. and L.G. Morgan. 1990. The potential for biological effects of sediment-
absorbed contaminants tested in the National Status and Trends Program. NOAA
Technical Memorandum NOS OMA 52. U.S. National Oceanic and Atmospheric
Administration, Seattle, Washington, 175 pp.
Long, E.R., D.D. MacDonald, S.L. Smith, FD. Calder. 1995. Incidence of adverse biological
effects within ranges of chemical concentrations in marine and estuarine sediments.
Environmental Management. 19(1):81-97.
References / OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
Mitchell, D.F.,, T. Mounce, J. Morton, K. Sullivan, M. Moore, and P. Downey. 1996. 1995
Annual fish and shellfish report. MWRA Environmental Quality Department Technical
Report Series No. 96-3. Massachusetts Water Resources Authority, Boston, MA. 112 pp.
Mitchell, D.F., M. Wade, W. Sung, and M. Moore. 1997.
1996 Toxics Issues Review Report. Draft.
MWRA. 1991. Massachusetts Water Resources Authority - Effluent Outfall Monitoring
Plan Phase I: Baseline Studies. MWRA Environmental Quality Department Misc. Report
No. ms-2. Massachusetts Water Resources Authority, Boston, MA. 95 pp.
MWRA. 1995. Massachusetts Water Resources Authority - Effluent Outfall Monitoring
Plan Phase II: Post Discharge Monitoring (Draft). Massachusetts Water Resources
Authority, Boston, MA. Draft 11/95.
MWRA. 1997. Contingency Plan. Massachusetts Water Resources Authority. 41 pp.
MWRA Web Site. http:\www.mwra.com
National Research Council. 1993. Managing Wastewater in Coastal Urban Areas. National
Academy of Sciences, National Academy Press, Washington, D.C.
Glossary / OUTFALL MONITORING OVERVIEW REPORT: 1995 - MWRA
Glossary
The following descriptions are not formal definitions but convey the sense of usage in this
report.
Algae - phytoplankton, the microscopic plants that drift with the currents. They are usually
single celled but may form colonies. There are many species that form the community
assemblage in a sample of seawater. Phytoplankton are eaten (grazed on) by zooplankton,
larger but still very small animals which also drift with the currents. Zooplankton, in turn,
are eaten by animals higher up the food chain. Large multicellular algae are called
macroalgae and are usually attached to the sea floor. Although plants are an essential part
of the food chain, excess nutrients may make them too numerous or favor undesirable
forms.
Apparent redox potential discontinuity depth - RPD. The visually measured thickness of
upper light-colored, and thus apparently well-oxygenated, layer in bottom sediments.
Bioturbation - mixing of the sediment strata by animals, which bring deeper sediment to
the surface as they burrow, and flush aerated bottom water into the mud by way of their
burrows and feeding activity.
Chlorophyll - the green pigment in plants that supports photosynthesis in the presence of
adequate light. Chlorophyll a is commonly used as a measure of total algal biomass.
Denitrification - the reduction of nitrate to nitrite and then to nitrogen gas.
Drumlin - elongated piles of glacial debris left behind after the glacier recedes.
Epibenthic organisms - bottom-dwelling animals that live upon, rather than within, a sub-
strate such as impenetrable rock.
Eutrophication - a process of excessive algal growth that may result in dissolved oxygen
depletion (hypoxia).
Hypoxia - a state of low dissolved oxygen in which sensitive animals may suffocate.
Infauna - bottom-dwelling animals that live within the sediments.
Mixing zone - region in the immediate vicinity of the diffuser where initial mixing and dilu-
tion occurs. The defined size of the mixing zone reflects the designed dilution properties of
the diffusers. An outfall would violate expectations if dilution is not sufficient to meet
water quality criteria at the edge of the mixing zone.
MWRA + OUTFALL MONITORING OVERVIEW REPORT: 1995 / Glossary
Nearfield or near field - a region near the new outfall which receives more intensive
sampling due to the expectation that effects are most likely to be manifest there. The def-
inition of the nearfiled varies with the study type, reflecting the mobility of water as com-
pared to sediments. Water column monitoring defines the nearfield as the area within a
rectangle with sides 5 km from the outfall. Beyond that is the farfield, which includes the
rest of Massachusetts Bay, Cape Cod Bays, and Boston Harbor. Benthic monitoring
defines the nearfield as the area within 2 km of the new outfall. Beyond that is the mid-
field (2-7 km away) and the farfield (greater than 7 km).
Primary production - the process by which algae produce organic carbon from carbon
dioxide through photosynthesis. Growth requires this carbon as well as nitrogen for pro-
tein and phosphorus for nucleic acids. In addition, silica is required by diatoms for their
outer cell walls.
Remineralization - Degradation of algal biomass into soluble components which are then
available again for uptake and growth by other algae. The carbon, nitrogen, and phospho-
tus in particulate organic matter are decomposed to carbon dioxide, urea, nitrate, ammonia,
and phosphate. Remineralization is the reverse of growth.
Respiration - the process of dissolved oxygen consumption by living organisms. It is the
reverse of photosynthesis.
MWRA + OUTFALL MONITORING OVERVIEW REPORT: 1995 / Acronyms
Acronym Summary
BOD
cBOD
CHV
DECS
DIN
DO
EPA
ER-L
ERM
LABs
biochemical oxygen demand
carbonaceous biochemical oxygen
demand
centrotubular hydropic vacuola-
tion, a fish liver lesion
Detailed Effluent Characterization
Study
dissolved inorganic nitrogen
dissolved oxygen
U.S. Environmental Protection
Agency
NOAA low effects range values for
sediment, rarely associated with
toxic effects
NOAA median effects range values,
often associated with toxic effects
linear alkyl benzenes
LC50 concentration for 50% lethality of
bioassay test organisms
MADEP Massachusetts Dept. of
Environmental Protection
nBOD nitrogenous biochemical
oxygen demand
NMFS _ National Marine Fisheries Service
NOEC no observable effect concentration
NPDES National Pollutant Discharge
Elimination System
PAHs _ polyaromatic hydrocarbons
PCBs polychlorinated biphenyls
ppb parts per billion
ppm __ parts per million
RPD redox potential discontinuity
TSS __ total suspended solids
USGS U.S. Geological Survey
WQC = Water Quality Criteriarelated records
Records whose documents say similar things, nearest first.
- Water & harborMassachusetts Water Resources AuthorityDeer Island outfall monitoring overview, 1999
- Water & harborMassachusetts Water Resources AuthorityDeer Island outfall monitoring overview, 2000
- Environmental permitU.S. Environmental Protection AgencyDeer Island treatment plant discharge permit (MA0103284), 2023 draft
- Water & harborMassachusetts Water Resources AuthorityDeer Island outfall monitoring overview, 1996
- Water & harborMassachusetts Water Resources AuthorityDeer Island outfall monitoring overview, 2002