Flood Insurance Study, effective September 25, 2009

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Federal Emergency Management Agency 
FLOOD INSURANCE STUDY NUMBER
25025CV000A 
SUFFOLK COUNTY,
MASSACHUSETTS
(ALL JURISDICTIONS)
COMMUNITY NAME COMMUNITY NUMBER 
BOSTON, CITY OF 250286
CHELSEA, CITY OF 250287
REVERE, CITY OF 250288
WINTHROP, TOWN OF 250289
Effective Date: September 25, 2009
SUFFOLK COUNTY

NOTICE TO
FLOOD INSURANCE STUDY USERS
Communities participating in the National Flood Insurance Program have established repositories
of flood hazard data for floodplain management and flood insurance purposes. This Flood
Insurance Study (FIS) may not contain all data available within the repository. It is advisable to
contact the community repository for any additional data.
Selected Flood Insurance Rate Map panels for the community contain information that was
previously shown separately on the corresponding Flood Boundary and Floodway Map panels
(e.g., floodways, cross sections). In addition, former flood hazard zone designations have been
changed as follows:
Old Zone New Zone
A1 through A30 AE
V1 through V30 VE
B X
C X
Part or all of this Flood Insurance Study may be revised and republished at any time. In addition,
part of this Flood Insurance Study may be revised by the Letter of Map Revision process, which
does not involve republication or redistribution of the Flood Insurance Study. It is, therefore, the
responsibility of the user to consult with community officials and to check the community
repository to obtain the most current Flood Insurance Study components.
Initial Countywide FIS Effective Date: September 25, 2009

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TABLE OF CONTENTS
Page
1.0 INTRODUCTION 1
1.1 Purpose of Study 1
1.2 Authority and Acknowledgments 1
1.3 Coordination 2
2.0 AREA STUDIED 3
2.1 Scope of Study 3
2.2 Community Description 7
2.3 Principal Flood Problems 9
2.4 Flood Protection Measures 11
3.0 ENGINEERING METHODS 12
3.1 Hydrologic Analyses 12
3.2 Hydraulic Analyses 15
3.3 Coastal Analyses 17
3.4 Vertical Datum 37
4.0 FLOODPLAIN MANAGEMENT APPLICATIONS 38
4.1 Floodplain Boundaries 39
4.2 Floodways 40
5.0 INSURANCE APPLICATIONS 45
6.0 FLOOD INSURANCE RATE MAP 46
7.0 OTHER STUDIES 48
8.0 LOCATION OF DATA 49 
9.0 BIBLIOGRAPHY AND REFERENCES 49

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TABLE OF CONTENTS - continued
Page
FIGURES
Figure 1 – Area Location Map in Revere 24
Figure 2 – Transect Schematic 37
Figure 3– Floodway Schematic 42
TABLES
Table 1 – CCO Meetings Dates for Precountywide FISs 3
Table 2 – Flooding Sources Studied by Detailed Methods 3
Table 3 – Flooding Sources Studied by Approximate Methods 5
Table 4 - Letters of Map Change 6
Table 5 - Population and Total Area by Community 7
Table 6 – Summary of Discharges 14
Table 7 – Manning’s “n” Values 17
Table 8 - Area Location Descriptions in Revere 23
Table 9 – Summary of Precountywide Stillwater Elevations 25
Table 10 – Precountywide Transect Descriptions 30
Table 11 – Summary of Precountywide Coastal Analyses 33
Table 12 – Floodway Data 43
Table 13 – Community History Map 47
EXHIBITS
Exhibit 1 - Flood Profiles
Charles River Panels 01P-05P
Mill Creek Panel 06P

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TABLE OF CONTENTS - continued
EXHIBITS - continued
Exhibit 1 - Flood Profiles - continued
Mother Brook Panels 07P-09P
Muddy River Panels 10P-16P
Neponset River Panels 17P-28P
Stony Brook Panels 29P-34P
Exhibit 2 - Flood Insurance Rate Map Index
Flood Insurance Rate Map

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FLOOD INSURANCE STUDY
SUFFOLK COUNTY [ALL JURISDICTIONS]
1.0 INTRODUCTION
1.1 Purpose of Study
This Flood Insurance Study (FIS) revises and updates information on the existence
and severity of flood hazards in the geographic area of Suffolk County, including
the Cities of Boston, Chelsea, Revere and the Town of Winthrop; (referred to
collectively herein as Suffolk County), and aids in the administration of the
National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of
1973. This study has developed flood-risk data for various areas of the community
that will be used to establish actuarial flood insurance rates and to assist the
community in its efforts to promote sound floodplain management. Minimum
floodplain management requirements for participation in the National Flood
Insurance Program (NFIP) are set forth in the Code of Federal Regulations at
44 CFR, 60.3.
In some states or communities, floodplain management criteria or regulations may
exist that are more restrictive or comprehensive than the minimum Federal
requirements. These criteria take precedence over the minimum federal criteria for
purposes of regulating development in the floodplain, as set forth in the Code of
Federal Regulations at 44 CFR, 60.3. In such cases, the more restrictive criteria
take precedence and the state (or other jurisdictional agency) will be able to explain
them.
1.2 Authority and Acknowledgments
The sources of authority for this FIS report are the National Flood Insurance Act of
1968 and the Flood Disaster Protection Act of 1973.
Boston, City of: The hydrologic and hydraulic analyses for the
November 2, 1990 study represent a revision of the
original October 1, 1983 analyses prepared by Harris-
Toups Associates for the Federal Emergency
Management Agency (FEMA), under Contract No.
H-4024. The work for the original 1983 study was
completed in November 1979. The hydrologic and
hydraulic analyses for this updated 1990 study were
prepared by Dewberry & Davis for FEMA, under
Contract No. EMW-85-C-2044. This work was
completed in December 1987.

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Chelsea, City of: The hydrologic and hydraulic analyses for the
original February 2, 1982 study were prepared by
Anderson Nichols & Co., Inc., for FEMA, under
Contract No. H-4524. This work was completed in
May 1980.
Revere, City of: The hydrologic and hydraulic analyses for the
original April 16, 1984, FIS report and the October
16, 1984, Revere FIRM (hereinafter referred to as the
1984 Revere FIS), were prepared by Stone & Webster
Engineering Corporation for FEMA, under Contract
No. H-4772, Modification No. 5. That work was
completed in April 1983.
The hydrologic and hydraulic analyses for the August
20, 2002 revision were prepared by Roald Haestad,
Inc., for FEMA, under Contract No. EMB-1999-CO-
0564. This work was completed in November 2000.
Winthrop, Town of: The hydrologic and hydraulic analyses for the
original and revised February 15, 1984 FIS were
prepared by Stone & Webster Engineering
Corporation for FEMA, under Contract No. H-4772.
This work was completed in January 1983.
For this countywide FIS, no new hydrologic or hydraulic analyses were performed.
Base map information shown on this FIRM was derived from digital
orthophotography. Base map files were provided in digital form by Massachusetts
Geographic Information System (MassGIS). Ortho imagery was produced at a
scale of 1:5,000. Aerial photography is dated April 2005. The projection used in
the preparation of this map was Massachusetts State Plane mainland zone
(FIPSZONE2001). The horizontal datum was NAD 83, GRS80 spheroid.
1.3 Coordination
The purpose of an initial Consultation Coordination Officer's (CCO) meeting is to
discuss the scope of the FIS. A final CCO meeting is held to review the results of
the study.
The dates of the initial and final CCO meetings held for the incorporated
communities within Suffolk County are shown in Table 1, “CCO Meeting Dates for
Precountywide FISs.”

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TABLE 1: CCO MEETING DATES FOR PRECOUNTYWIDE FISs
Community Name Initial CCO Date Intermediate CCO Date Final CCO Date
City of Boston April 13, 1987 * April 11, 1989
City of Chelsea May 13, 1977 July 27, 1980 July 22, 1981
City of Revere January 4, 2000 * August 28, 2001
Town of Winthrop April 13, 1978 December 13, 1979 September 26, 1983
* Data not Available
For this countywide revision, no initial CCO meeting was held. The results of the
study were reviewed at the final CCO meetings held on December 17 th , 2008 and
January 14 th , 2009, and were attended by representatives of FEMA, Massachusetts
Department of Conservation and Recreation (DCR), CDM, Ocean & Coastal
Consultants Inc. (OCC), and Suffolk County communities. All problems raised at
that meeting have been addressed in this study.
2.0 AREA STUDIED
2.1 Scope of Study
This FIS report covers the geographic area of Suffolk County, MA including the
incorporated communities listed in Section 1.1. The areas studied by detailed
methods were selected with priority given to all known flood hazards and areas of
projected development or proposed construction.
All or portions of the flooding sources listed in Table 2, “Flooding Sources Studied
by Detailed Methods,” were studied by detailed methods in the precountywide
FISs. Limits of detailed study are indicated on the Flood Profiles (Exhibit 1) and on
the DFIRM. 
TABLE 2: FLOODING SOURCES STUDIED BY DETAILED METHODS 
Flooding Source Description 
Areas of shallow flooding Along portions of Winthrop Parkway and Revere
Beach Boulevard in the City of Revere 
Atlantic Ocean For the entire coastline within the Town of
Winthrop 
Boston Harbor For the entire coastline within the Town of
Winthrop

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TABLE 2: FLOODING SOURCES STUDIED BY DETAILED METHODS – cont’d 
Flooding Source Description 
Broad Sound For its entire length within the Town of Winthrop 
Charles River From upstream of the New Charles River Dam in
the City of Boston to the City of Boston-Town of
Dedham corporate limits 
Coastal Flooding For the entire coastline within the City of Revere,
including its wave action from the Atlantic Ocean
and the tidal portions of the Saugus, Chelsea, and
Pine Rivers, as well as Belle Isle Inlet 
Linden Brook From its confluence with Town Line Brook to the
upstream corporate limits in the City of Revere 
Mill Creek From its confluence with the Chelsea River to
approximately 5,400 feet upstream. 
Mother Brook From its confluence with Neponset River to the
City of Boston-Town of Dedham corporate limits. 
Muddy River From its confluence with Charles River to Willow
Pond 
Neponset River From upstream of the dam at Lower Mills to the
Boston-Dedham corporate limits 
Stony Brook From upstream of the entrance to the Stony
Brook culvert to Turtle Pond in the City of
Boston. 
Tidal Flooding In the City of Chelsea, including its wave action
from the Atlantic Ocean affecting the Island End
River, the Mystic River, Boston Harbor, and the
Chelsea River

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TABLE 2: FLOODING SOURCES STUDIED BY DETAILED METHODS – cont’d 
Flooding Source Description 
Town Line Brook From U.S. Route 1 to the upstream corporate
limits in the City of Revere
Portions of the Muddy River within the detailed study limits are referred to locally
as the Back Bay Fens. Wherever referenced in this report, the name Muddy River
shall be assumed to include the area known as the Back Bay Fens.
All or portions of numerous flooding sources in the county were studied by
approximate methods. Approximate analyses were used to study those areas having
a low development potential or minimal flood hazards. The scope and methods of
study were proposed to, and agreed upon, by FEMA and the individual
communities within Suffolk County.
All or portions of the flooding sources listed in Table 3, “Flooding Sources Studied
by Approximate Methods,” were studied by approximate methods in the
precountywide FISs. 
TABLE 3: FLOODING SOURCES STUDIED BY APPROXIMATE METHODS 
Flooding Source Community 
Atlantic Ocean Chelsea, Revere, Winthrop 
Boston Harbor Boston, Chelsea, Winthrop 
Boston Inner Harbor Boston 
Broad Sound Winthrop 
Chandler's Pond Jamaica Pond Boston 
Charles River Boston 
Chelsea River Boston, Chelsea, Revere 
Chestnut Hill Reservoir Boston 
Dorchester Bay Boston 
Island End River Chelsea 
Linden Brook Revere 
Mill Creek Chelsea, Revere 
Mother Brook Boston 
Muddy River including Back Bay Fens Boston 
Mystic River Boston, Chelsea 
Neponset River Boston 
Pines River Revere

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TABLE 3: FLOODING SOURCES STUDIED BY APPROXIMATE METHODS – cont’d 
Flooding Source Community 
Saugus River Revere 
Sawmill Brook Boston 
Stony Brook Boston 
Town Line Brook Revere 
Unnamed Ponding Area near Genoa Street Revere 
This FIS also incorporates the determinations of letters issued by FEMA resulting
in map changes (Letter of Map Revision [LOMR], Letter of Map Revision – based
on Fill [LOMR-F], and Letter of Map Amendment [LOMA]), as shown in Table 4,
“Letters of Map Change.”
TABLE 4 – LETTERS OF MAP CHANGE
Community Case Number Flooding Source Letter Date
Boston, City of 04-01-013P Massachusetts Bay/ 07/09/2004
Boston Harbor
Boston, City of 08-01-1020P Dorchester Bay 12/05/2008
Revere, City of 07-01-0489P Broad Sound 09/20/2007 
For this countywide revision, the 1- and 0.2-percent-annual-chance floodplain
boundaries for the Atlantic coastline in Suffolk County were redelineated using
more up to date topographic information, including MassGIS and LiDAR data,
which meets the accuracy standards for flood hazard mapping
(https://www.mass.gov/mgis/ and https://maps.csc.noaa.gov.TMC/). No new
detailed or approximate studies were performed.
Detail studied streams that were not restudied as part of this revision may include a
profile baseline on the FIRM. The profile baselines for these streams were based on
the best available data at the time of their study and are depicted as they were on the
previous FIRMs. In some cases the transferred profile baseline may deviate
significantly from the channel or may be outside of the floodplain.

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2.2 Community Description
Suffolk County is located on the seacoast of the Atlantic Ocean in eastern
Massachusetts. In Suffolk County there are four (4) incorporated communities. The
Cities of Boston, Chelsea, and Revere and the Town Winthrop.
Suffolk County is bordered by the Atlantic Ocean on the east; by Essex County,
including the towns of Lynn and Saugus, to the north; by Middlesex County,
including the towns of Melrose, Malden, Everett, Somerville, Cambridge,
Watertown and Newton, to the west; and by Norfolk County, including the towns of
Needham, Dedham, Canton, Milton and Quincy, to the South. It is 44 miles from
Providence, Rhode Island, 106 miles from Portland, Maine, and 93 miles from
Hartford, Connecticut.
According to the U.S. Census, the population of Suffolk County was 689,807 in
2000. The land area of Suffolk County consists of 120.19 square miles. All
communities in Suffolk County included in this FIS, along with their population
and total area, are listed in Table 5, “Population and Total Area by Community.”
TABLE 5 – POPULATION AND TOTAL AREA BY COMMUNITY
Community Total Area (Sq. mi) 1 Population
Boston, City of 89.63 589,141
Chelsea, City of 2.48 35,080
Revere, City of 10.03 47,283
Winthrop, Town of 8.3 18,303
1 U.S. Census Bureau, 2000 Census of Population and Housing (Reference 1)
Suffolk County is the hub of a larger metropolitan area, serving some 3.25 million
people; the sixth largest population center in the United States.
The climate of Suffolk County is moderate and can be described as a continental
climate. Summers are warm and humid, while winters are cold, windy and snowy.
The hottest month is July, with an average high of 82 degrees Fahrenheit ( º F) and
an average low of 66 º F. The coldest month is January, with an average high of 36F
and an average low of 22 º F. The mean annual temperature is 50 degrees Fahrenheit
( º F). The temperature ranges from an average of 29°F in January to an average of
72°F in July (Reference 2). The average annual rainfall is 42 inches. The average
annual snowfall is approximately 40.9 inches (Reference 3). . There is no dry
season and, on the average, no dry spell lasts more than two weeks. From June to
September, rainfall usually occurs in the form of showers or thunderstorms, which
produce heavy, sometimes excessive, amounts of rain. Throughout the year, the
heaviest gales are usually from the northeast or east and are more common and
severe during the winter. Though the coastal location on the North Atlantic
moderates temperatures in Suffolk County, it also makes the County very prone to

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Nor’easter weather systems, which can result in an abundance of snow and rain.
(Reference 4).
Boston was originally a peninsula with great areas of salt marsh to the north, along
the banks of the Charles and Mystic Rivers, and at the mouth of the Neponset River
to the south. Large areas of filled land occur in the Back Bay, the West End, South
Boston, Dorchester, Charlestown and East Boston. In 1910, a dam on the Charles
River at Leverett Street was constructed to prevent tidal flooding of the lowlands, to
cover unsightly tidal flats at the mouth of the river, and to create an aesthetically
pleasing recreational pool – now known as the Charles River Basin.
However, the creation of the basin accelerated growth along its banks, which in turn
resulted in the conversion of many former open spaces to developed and paved
areas. This change increased the speed and amount of runoff above the existing
dam, making it inadequate to carry the discharges predicted. The U.S. Army Corp
of Engineers (USACE) constructed a new dam at Warren Avenue to replace the
1910 dam at Leverett Street in order to accommodate the increased run-off. The
Warren Avenue bridge was removed preconstruction of the Charles River Dam
Local Protection Project that was initiated back in November, 1972. The project
was completed in May 1978 and it situated the new dam approximately 2,250 feet
downstream of the old Charles River Dam.
The land throughout the City of Boston is densely settled, except for limited areas
in the west. 
The City of Revere is also densely developed and attracts both permanent and
transient populations. Coastal development in Revere is a mixture of residential,
commercial, industrial, and recreational. Located along the eastern shore, from
Point of Pines to Elliott Circle, is Revere Beach, a popular Metropolitan District
Commission recreational facility. The beach experiences severe erosion problems.
A breakwater is located at the southern end of Revere Beach at Cherry Island Bar.
Of the Town of Winthrop’s total land area, the majority of the land is classified as
urban land, Within urban land space, high density residential areas comprises more
than half. (Reference 5). The recreational lands consist primarily of the beaches
along the eastern shore of the town. Exposure of the beaches to the open coast has
caused severe erosion. To retard erosion, a 0.4-mile long breakwater was
constructed 0.2 mile off of and parallel to Winthrop Beach. Coastal development is
primarily residential and recreational. Because Winthrop is long and narrow in
shape, the entire town is within the Massachusetts Coastal Zone.
The coastline of the City of Chelsea is heavily developed with commercial and
industrial properties, predominately related to petroleum products and storage. The
Mill Creek watershed is heavily developed with commercial and residential
properties.
The topography of the County is generally level, with elevations ranging from sea
level to 180 feet. Occasional hills composed of glacial till, rise as high as 300 feet.

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The tidal shoreline along the Atlantic Ocean is 87.7 miles in length. Most of the
county was formed by glacial till; its coastline includes scattered coves, beaches,
and rocky shoals. Located at the northwest boundary of Winthrop is Belle Isle
Marsh, a 250-acre salt marsh that is one of the last remaining salt marshes in the
Boston Harbor region.
The Charles River has its headwaters in Echo Lake in Hopkinton. It flows generally
northeast, finally becoming the northern boundary of the City of Boston, before
discharging into Boston Harbor. It has a drainage area of approximately 300 square
miles. Mother Brook, beginning as a partial diversion of the Charles River in the
Town of Dedham, flows east through the Hyde Park section of Boston, discharging
into the Neponset River. Flows in Mother Brook are limited to approximately one-
third that of the Charles River. Muddy River rises out of Jamaica Pond and flows
north, passing through highly-developed areas of Boston and Brookline before
discharging into the Back Bay Fens. The Fens then empty into the Charles River
Basin. The Neponset River originates in the Neponset Reservoir in Foxborough. It
flows generally northeast, becoming the southern boundary for the City of Boston
before discharging into Dorchester Bay. Stony Brook originates in Turtle Pond and
flows south through Stony Brook Reservation before entering the Stony Brook
culvert.
Boston Harbor is bordered by the Atlantic Ocean to the east and is protected on the
north by Winthrop Peninsula and to the south by Hull Peninsula. From north to
south, Boston Harbor is bounded by the Logan International Airport, East Boston,
Charlestown, the Mystic and Charles Rivers, the downtown area, South Boston,
Dorchester, and the Neponset River. The harbor has a number of islands including
Deer, Spectacle, Thompson, Long and Gallops Islands. The entire coastline is
densely developed, and much of the waterfront is under redevelopment pressure.
Much of the recent construction has involved the downtown waterfront area,
including condominiums, offices, parks and commercial establishments.
2.3 Principal Flood Problems
Investigations into flooding within the corporate limits of Boston have revealed that
there has been severe flooding resulting in extensive damage, especially to the
Charles River Basin and the surrounding lowlands. The problem is caused primarily
by the difference between the established normal water level in the basin and the
high tide in the harbor. In the flood of August 1955, 12.5 inches of rain coupled
with a peak high tide of 8.2 feet resulted in raising the basin elevation to a record
high of 6.90 feet. Over 1,750 acres, mostly highly-developed Cambridge and
Boston, lying along the 8.6-mile long basin were subject to serious flooding. The
1955 hurricane, equivalent to a 1-percent-annual-chance storm, resulted in flood
damage along the lower Charles River amounting to 5.5 million dollars. The same
flood level in 1980 would have resulted in an estimated damage of 20 million
dollars. In March 1968, 7.7 inches of rain combined with the spring thaw produced
the second highest basin levels of 4.5 feet, inundating many areas along Storrow
Drive. Although the peak discharge upstream was the same as the 1955 flood, the

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river peak did not coincide with the tidal peaks as in the 1955 flood, and resulting
damage was less extensive. Flooding problems from the 1955 and 1968 storms also
occurred along the Neponset River in the Hyde Park area. Numerous private
properties, automobiles and roadways were damaged as a result of the storm.
Flooding also occurs along the coastline of Boston and Chelsea and in the low-lying
coastal areas of Revere and Winthrop, greatly influenced by storm surge elevations
of Boston Harbor that result from severe storms. The most recent example of severe
flooding was during the northeaster of February 1978, which was comparable to a
1-percent-annual-chance flood event. Elevations of flooding ranged from 8.6 to
10.1 feet, which caused one to three feet of flooding in areas such as Rowes, India,
Long, Commercial and Battery Wharves. Low-level flooding occurred at a number
of East Boston locations such as East Boston Pier, the airport access road, and
several parking lots on commercial piers. More serious damage occurred as a result
of wave action. The recorded flood elevation was 9.8 feet at the New Charles River
Dam, 9.5 feet at the U.S.S. Constitution, and 9.5 feet at the Commonwealth Pier
gage. The 1978 northeaster caused significant damage in excess of $15 million in
the City of Revere. Other significant storms to cause flooding in Revere include the
storms of December 1909 and 1959 (a flood event that had approximately 0.6- and
6.7-percent-annual-chance of occurring or being exceeded, respectively) and
February 1972 (approximate recurrence of 4-percent-annual-chance).
In Chelsea, severe flooding due to poor drainage frequently occurs near Mill Creek
upstream of U.S. Route 1. This area was not studied in detail because of its small
drainage area. Minor flooding has been reported from residents near Mill Creek
adjacent to Forbes Park (formerly Forbes Industrial Park), though no structural
damage or injuries have been reported.
The heavily developed areas of Point of Pines and Oak Island, in Revere, have
suffered severe damage from storms annually. The Point of Pines area is subject to
coastal and riverine flooding. The encroachment of development into the Saugus
River- Pines River Marsh has reduced storage capacity of the marsh and increased
the flooding potential in the area. The Beachmont area, which faces the ocean and
backs up to Belle Isle Marsh, experiences flooding as a result of storms and high
tides.
In Winthrop, the majority of storms cause damage only to low coastal roads, boats,
beaches, and seawalls. Occasionally, a major storm accompanied by strong onshore
winds results in high tides and wave activity that cause extensive property damage
and erosion. Some of the more significant storms in the Winthrop area include those
of December 1909, December 1959, February 1972, and February 1978. The storms
had approximate recurrence of 0.6-, 6.7-, 4-, and 1.1-percent annual chance,
respectively. Harbors, marinas, and residential and commercial developments were
damaged by the storms.

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2.4 Flood Protection Measures
The primary flood problem within the City of Boston is in the area along the
Charles River Basin. In 1910, a dam on the Charles River at Leverett Street was
constructed, but with newly developed and paved areas, the dam became inadequate
to carry the discharge predicted. The USACE replaced the Leverett Street dam with
the new and improved Warren Avenue Dam to accommodate the growth of
metropolitan Boston.
In the early 1970’s the Charles River Dam Local Protection Project was initiated,
thus removing the Warren Avenue Dam and replacing it with the current Charles
River Dam, which provides flood protection to 2,440 acres of urban property along
the banks of the Charles River. The project consisted of the construction of an
earthfill and concrete dam with stone slope protection stretching between Boston
and Charlestown. The dam is 400 feet long with an elevation of 12.5 feet above
mean sea level. The connecting pumping station is 190 feet long and 122 feet high
and contains six pumps. There are three navigation locks for commercial and
recreational vessels. Two of the locks, for small recreational craft, each measure
200 feet long, 22 feet wide, and eight feet deep. The third lock, 40 feet wide, 300
feet long, and 17 feet deep, accommodates commercial vessels, large recreational
boats, and the overflow of small craft during peak days.
The Baker Dam is located within the boundaries of the Dorchester/Milton Lower
Mills Industrial Complex along the Neponset River and was originally built in the
mid-1960’s for the purpose of privately owned industrial mills. In the wake of
hurricane Diane, the MDC took over the Lower Neponset, including its dams. In
1962, the MDC flood control project began, covering a stretch of the Neponset
River from the freshwater limit to upstream of the Neponset Valley Parkway and
CONRAIL crossing. The Baker dam was rebuilt in the same general style as the
original, except the top of the dam was lowered by three or more feet to improve its
discharge capacity during storm events. The average water level at Baker was also
reduced by about three feet, thus providing better flood protection. This project
also included channel straightening and channel and bridge modifications. These
measures, in conjunction with proper operation of the floodgates on the dams, will
effectively contain the 1- and 0.2-percent-annual-chance floods within the channel
banks. Much of the land bordering riverine areas has been designated as parkland,
thereby limiting development in floodplain areas. Flood control measures along the
harbor are scattered, but include such measures as seawalls and rip-rapping.
The USACE has is currently conducting a feasibility study regarding the removal of
the Baker Dam for Neponset River restoration purposes
(http://www.neponset.org/CurrentProjects.htm). It has been recommended by the
Massachusetts Riverways Program’s Technical Advisory Committee to remove this
dam, as it is no longer serving the purpose for which it was built.
In Chelsea, a tide gate exists on Mill Creek at the culvert under the east ramp of the
U.S. Route 1 interchange with State Route 16. In 1979, the state locked the gate in

12
an open position to help alleviate the occasional flooding problems upstream. There
are no other flood protection structures or measures in Chelsea.
In Revere and Winthrop, the MDC provides concrete seawalls and stone revetments
to protect coastal highways. Other protective structures are generally built and
maintained by the local municipality and private property owners to satisfy
individual requirements within their financial capabilities. These structures include
such backshore protection as timber and steel sheet piles, bulkheads, stone
revetments, concrete seawalls, and pre-cast concrete units (Reference 6). Limited
financial resources sometimes result in less than adequate protection.
3.0 ENGINEERING METHODS
For the flooding sources studied by detailed methods in the community, standard
hydrologic and hydraulic study methods were used to determine the flood-hazard data
required for this study. Flood events of a magnitude that is expected to be equaled or
exceeded once on the average during any 10-, 50-, 100-, or 500-year period (recurrence
interval) have been selected as having special significance for floodplain management and
for flood insurance rates. These events, commonly termed the 10-, 50-, 100-, and 500-year
floods, have a 10-, 2-, 1-, and 0.2-percent chance, respectively, of being equaled or
exceeded during any year. Although the recurrence interval represents the long-term,
average period between floods of a specific magnitude, rare floods could occur at short
intervals or even within the same year. The risk of experiencing a rare flood increases
when periods greater than 1 year are considered. For example, the risk of having a flood
that equals or exceeds the 1-percent-annual-chance flood in any 50-year period is
approximately 40 percent (4 in 10); for any 90-year period, the risk increases to
approximately 60 percent (6 in 10). The analyses reported herein reflect flooding
potentials based on conditions existing in the community at the time of completion of this
study. Maps and flood elevations will be amended periodically to reflect future changes.
3.1 Hydrologic Analyses
Hydrologic analyses were carried out to establish peak discharge-frequency
relationships for floods of the selected recurrence intervals for each flooding source
studied by detailed methods affecting the county
For each community within Suffolk County, the hydrologic analyses described in
their previous FIS reports have been compiled and summarized below.
Precountywide Analyses
Peak discharge estimates for the upper reach of the Charles River for the 10-, 2-, 1-,
and 0.2-percent-annual-chance floods were based on a log-Pearson Type III
analysis of the USGS gage data from the gages (no. 01104500 and no. 01103500)
located at Waltham and Charles River Village, respectively (Reference 7).

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As a result of the 8,400 cfs pumping capacity of the New Charles River Dam, peak
discharge estimates for the Charles River Basin for floods of the selected recurrence
intervals were not determined. Peak inflow hydrographs developed by the USACE
were used to determine pumping curves so as to maintain basin levels near the
normal elevation of 2.5 feet during the 10-, 2-, and 1-percent-annual-chance floods
(Reference 8). Damage resulting from floodwaters along the Charles River Basin
begins at an elevation of 3.8 feet. During a 1-percent-annual-chance event, the
pumping station will control basin levels to an elevation of 3.5 feet, which is below
the level at which damage will occur. For the 0.2-percent-annual-chance event,
basin levels will be held to an elevation of 5.2 feet and minimal damage will result.
This assumes, however, that the basin will not be drawn down and that sluicing will
not be possible.
Mother Brook acts as a diversion channel from the Charles River to the Neponset
River. The discharges for Mother Brook are limited by law to approximately one-
third of the peak discharge for the Charles River (Reference 9).
Peak discharge estimates for the Muddy River and Back Bay Fens for floods of the
selected recurrence intervals were not calculated, as the Muddy River and Back Bay
Fens act as a reservoir during periods of great runoff. For this reason, hydrologic
analyses were conducted to establish peak volume rather than peak discharge-
frequency data. Flood volume data was developed by the USACE using unit
hydrographs and rainfall-frequency analyses (References 8 and 10). This data was
checked for reasonableness and incorporated into this study.
Peak discharge-frequency estimates of the Neponset River for the 10-, 2-, 1-, and
0.2-percent-annual-chance floods were determined for the FIS for the Town of
Milton in Norfolk County and were incorporated into this study (Reference 11).
Peak discharge-frequency estimates for Stony Brook for the 10-, 2-, and 1-percent-
annual-chance floods were computed using the SCS peak discharge determination
methods for small watersheds (Reference 9). The 0.2-percent-annual-chance peak
discharge estimate was determined by linear extrapolation of a log-Pearson Type III
probability curve on the other floods.
Two high-water marks in Chelsea were obtained from the USGS. The elevation on
Mill Creek upstream of Broadway Avenue in Chelsea is 8.8, and the elevation on
the Chelsea River at the MDC Sewerage Division Maintenance Yard is 9.5
(Reference 12).
The Mill Creek discharges in Chelsea and Revere were obtained from a drainage
study of Mill Creek prepared for the Massachusetts Department of Public Works in
1975 (Reference 13). The analysis incorporated rainfall simulation modeling,
simulation of runoff, and the drainage system response to rainfall through the use of
a computerized catchments model. The 0.2-percent-annual-chance discharge was
extrapolated from the three calculated flow values.

14
Countywide Analyses
No new Hydrologic Analyses were conducted for this countywide FIS.
Peak discharge-drainage area relationships for the flooding sources studied by
detailed methods are shown in Table 6, “Summary  of Discharges”.
TABLE 6 - SUMMARY OF DISCHARGES
PEAK DISCHARGES (CUBIC FEET PER SECOND)
FLOODING
SOURCE AND
LOCATION
DRAINAGE
AREA
(SQUARE
MILES)
10-
PERCENT
ANNUAL
CHANCE
2-
PERCENT
ANNUAL
CHANCE
1-
PERCENT
ANNUAL
CHANCE
0.2-
PERCENT
ANNUAL
CHANCE
CHARLES RIVER
At upstream Boston-
Dedham corporate
limits
227 2125 3102 3578 4850
MILL CREEK
At confluence with
Chelsea River
1.3 600 1690 2300 4790
At mouth in City of
Chelsea
1.3 600 1690 2300 4790
MOTHER BROOK
At City of Boston
corporate limits
2.4 740 1210 1470 2250
NEPONSET RIVER
At dam at Lower
Mills in the City of
Boston
98 2450 3410 3730 4750

15
TABLE 6 - SUMMARY OF DISCHARGES – continued
PEAK DISCHARGES (CUBIC FEET PER SECOND)
FLOODING
SOURCE AND
LOCATION
DRAINAGE
AREA
(SQUARE
MILES)
10-
PERCENT
ANNUAL
CHANCE
2-
PERCENT
ANNUAL
CHANCE
1-
PERCENT
ANNUAL
CHANCE
0.2-
PERCENT
ANNUAL
CHANCE
STONY BROOK
At Stony Brook
culvert in the City of
Boston
13 90 150 200 286
3.2 Hydraulic Analyses
Analyses of the hydraulic characteristics of flooding from the sources studied were
carried out to provide estimates of the elevations of floods of the selected
recurrence intervals. Users should be aware that flood elevations shown on the
FIRM [Flood Insurance Rate Map (FIRM)] represent rounded whole-foot
elevations and may not exactly reflect the elevations shown on the Flood Profiles or
in the Floodway Data tables in the FIS report. Flood elevations shown on the FIRM
are primarily intended for flood insurance rating purposes. For construction and/or
floodplain management purposes, users are cautioned to use the flood elevation data
presented in this FIS in conjunction with the data shown on the FIRM.
Cross sections were field surveyed and located at close intervals above and below
bridges and culverts in order to compute the significant backwater effects of these
structures. All bridges, dams, and culverts in the county were field surveyed to
obtain elevation data and structural geometry. In long reaches between structures,
appropriate valley sections were also surveyed.
Locations of selected cross sections used in the hydraulic analyses are shown on the
Flood Profiles (Exhibit 1). For stream segments for which a floodway was
computed (Section 4.2), selected cross-section locations are also shown on the
FIRM.
The hydraulic analyses for this study were based on unobstructed flow. The flood
elevations shown on the Flood Profiles (Exhibit 1) are thus considered valid only if
hydraulic structures remain unobstructed, operate properly, and do not fail.
For each community within Suffolk County that has a previously printed FIS report,
the hydraulic analyses described in those reports have been compiled and are
summarized below.

16
Precountywide Analyses
In Boston, overbank extensions of field-surveyed channel cross sections, and
additional sections needed for hydraulic continuity were taken from topographic
maps at a scale of 1:1,200 with a 5 foot contour interval (Reference 14). Present
culvert conditions were used and recent modifications were taken into consideration
in the use of flood marks.
The overbank portions of the cross-section data for Mill Creek were obtained from
topographic maps prepared by photogrammetric methods (Reference 15). The
below-water sections were obtained by field measurement. All bridges and culverts
were field surveyed to obtain elevation data and structural geometry.
Water-surface elevations for Stony Brook, Mill Creek, Mother Brook, Neponset
River, and the upper reach of the Charles River were developed using the HEC-2
computer program developed by the USACE (Reference 16). Starting water-
surface elevations for Mill Creek were based on mean high-water elevations. The
storm surge elevations from the coastline were superimposed on the profile to the
location on Mill Creek where backwater flooding from the coast no longer exists.
Starting water-surface elevations for Stony Brook were taken from a rating curve
developed at the entrance to the Stony Brook culvert.
At one location on Mill Creek, the analysis indicates that the flow would be
supercritical. Because of the inherent instability of supercritical flow, critical depth
was assumed at this location when establishing the profile elevations for this study.
Water-surface elevations for floods of the selected recurrence intervals along the
Neponset River were obtained from a previously published report by Anderson-
Nichols Co. and the FIS for the Town of Milton in Norfolk County (References 11
and 17). They were checked for reasonableness and incorporated into this study.
For the Charles River Basin, elevations were developed using inflow hydrographs
in respect to the pumping capacity of the New Charles River Dam (References 8
and 18). Elevations along the Muddy River were developed using the "modified
puls" method of reservoir routing in conjunction with the discharge capacity of the
Charles River Basin (References 8, 10, 18 and 19). Elevations for the floods for the
Back Bay Fens, the Muddy River and the Charles River Basin were developed by
the USACE in their detailed analysis of the Charles River Basin (References 8 and
10).
In some locations, such as the Boston Harbor shoreline within Winthrop, water
levels were computed by correlating synthetically-produced water levels with
elevations obtained during historic floods (Reference 20). Historic flood damage
information was also used to ensure reasonable delineation of flood-prone areas
along the Revere and Winthrop shoreline (Reference 21).

17
The City of Revere has no qualifying bench marks within its corporate limits.
Countywide Analyses
No new Hydraulic Analyses were performed for this countywide FIS.
Roughness factors (Manning's "n") used in the hydraulic computations were
estimated based on field inspection of flood plain areas. The channel "n" and
overbank "n” values for the streams studied by detailed methods are shown in Table
7, “Manning’s “n” Values”:
TABLE 7- MANNING’S “n” VALUES
FLOODING SOURCE CHANNEL ”n” OVERBANK “n”
Charles River 0.025-0.035 0.065
Mill Creek 0.040 0.060-0.085
Mother River 0.015-0.100 0.100
Neponset River 0.035 0.060
Stony Brook 0.020-0.050 0.100
3.3 Coastal Analyses
Hydraulic analyses, considering storm characteristics and the shoreline and
bathymetric characteristics of the flooding sources studied, were carried out to
provide estimates of the elevations of floods of the selected recurrence intervals
along each of the shorelines.
Areas of coastline subject to significant wave attack are referred to as coastal high
hazard zones. The USACE has established the 3-foot breaking wave as the criterion
for identifying the limit of coastal high hazard zones (Reference 22). The 3-foot
wave has been determined as the minimum size wave capable of causing major
damage to conventional wood frame or brick veneer structures.
A wave height analysis was performed to determine wave heights and
corresponding wave crest elevations for the areas inundated by the tidal flooding. A
wave run-up analysis was performed to determine the height and extent of run-up
beyond the limit of tidal inundation. The results of these analyses were combined
into a wave envelope, which was constructed by extending the maximum wave run-
up elevation seaward to its intersection with the wave crest profile.
The methodology for analyzing the effects of wave heights associated with coastal
storm surge flooding is described in the National Academy of Sciences report
(Reference 23). This method is based on three major concepts.

18
First, a storm surge on the open coast is accompanied by waves. The maximum
height of these waves is related to the depth of water by the following equation:
Hb=0.78d
where Hb is the crest to trough height of the maximum or breaking wave and d is
the still-water depth. The elevation of the crest of an unimpeded wave is determined
using the equation:
ZW=S*+0.7H*=S*+0.55d
where Z, is the wave crest elevation, St is the still-water elevation at the site, and
H* is the wave height at the site. The 0.7 coefficient is the portion of the wave
height which reaches above the still-water elevation. Hb is the upper limit for H*.
The second major concept is that the breaking wave height may be diminished by
dissipation of energy by natural or man-made obstructions. The wave height
transmitted past a given obstruction is determined by the following equation:
Ht=BHi
where Ht is the transmitted wave height, Hi is the incident wave height, and B is a
transmission coefficient ranging from 0.0 to 1.0. The coefficient is a function of the
physical characteristics of the obstruction. Equations have been developed by the
NAS to determine B for vegetation, buildings, natural barriers such as dunes, and
man-made barriers such as breakwaters and seawalls (Reference 23).
The third concept deals with unimpeded reaches between obstructions. New wave
generation can result from wind action. This added energy is related to distance and
mean depth over the unimpeded reach.
For each coastal community within Suffolk County that has been studied prior to
this countywide update, the coastal analyses described in the previous FIS reports
have been compiled and are summarized below. This includes all communities
within Suffolk County.
Precountywide Analyses
In Boston, the coastal areas for which flood elevations have been determined
include the lands bordering Massachusetts Bay, Boston Harbor, and Dorchester
Bay, and along the Neponset, Charles, Mystic, and Chelsea Rivers to the limits of
tidal inundation. Water level fluctuations above astronomical tide levels at Boston
are caused primarily by the passage of hurricanes and winter storms known as
northeasters. Of these, the northeasters produce the more frequent and severe storm
tides.
Extreme water levels along the Boston shoreline are caused by the combination of
storm surges and high astronomical tides. Astronomical tide levels are extremely

19
important in the determination of total water levels as they have a mean range of 8.7
feet and a spring range of more than 11.2 feet. These ranges are considerably larger
than the expected storm surges, thus making the phasing of the astronomical tide
critical to the determination of total water levels.
Storm surges in the Boston area are caused mainly by onshore winds, wave setup
and low barometric pressures that cause a rise in the water-surface elevation. As
discussed above, these water level fluctuations are due primarily to the passage of
hurricanes and northeasters through the area. The dominant surge-producing storm
in the Boston area, as in most of the New England regions, is the northeaster. These
storms are typically less intense than hurricanes, but they occur more frequently and
are larger and slower-moving. Thus, they have a significantly greater probability of
combining with a high astronomical tide causing an extreme high-water level.
Hurricanes in the New England region are considerably weaker than the very
destructive storms found in the Gulf of Mexico and off the southeastern coast of the
United States. These factors, along with the relatively narrow continental shelf off
Boston, combine to reduce the effect of the hurricanes on the tide levels at the
coast.
A combined probabilistic-deterministic method was used in this study to develop
the coastal stillwater flood elevations in locations where tidal gage records are not
available. The probabilistic components of the study involved the determination of
probabilities of occurrence of various meteorological parameters that define
hurricanes and winter storms in the area. These probabilities are effectively constant
over large regions and thus may be used at locations where no direct measurements
have been made with any significant loss in accuracy. The deterministic component
of the study involved the calculation of the storm surge that would be caused by
various combinations of these meteorological parameters. The main steps involved
in the determination of flood levels are as follows:
1. Determination of probabilities of occurrence of various meteorological
parameters relevant to storm surge generation.
2. Development of numerical models to calculate the storm surge due to a particular
set of meteorological conditions. Numerical models were developed to represent the
outer coast, inner harbor and riverine areas.
3. Development of simple numerical models to allow rapid and inexpensive
calculation of surge levels at various locations.
4. "Calibration" of the simple numerical model to specific locations of interest
using the results of the more comprehensive numerical models.
5. Simulation of 500 years of storm tide data using a random generation of
meteorological parameters based on their historical probabilities of occurrence and
combination with a randomly phased astronomical tide.

20
6. Calculation of stillwater elevation return periods on the basis of the simulated
tide data.
A total of six numerical models were developed to calculated surge levels on the
open coast and inside the harbor. These models included:
WINTSRG - used to determine the open coast surge due to winter storms.
HURSRG - used to determine the open coast surge due to hurricanes.
INSRG - used to determine the surge at various locations inside the harbor due to
either winter storms or hurricanes using the output of WINTSRG or HURSRG as
boundary conditions.
RIVSRG - used to determine the surge at various locations along the riverine
sections due to either winter storms or hurricanes using the output of INSRG as
boundary conditions.
WINTSEL - used to determine the total still-water elevations due to the
combination of astronomical tides and storm surges from winter storms for the
development of 500 years of record.
HUSEL - used to determine the total still-water elevations due to the combination
of astronomical tides and hurricane surges for the development of 500 years of
record.
The development of these models is discussed in detail in the Coastal Flooding
Analysis (Reference 24). Briefly, the HURSRG, INSRG, and RIVSRG models
were developed based on the solution of the governing differential equations
outlined by Dean. The WINTSRG model was developed to account for the special
conditions caused by winter storms that control the development of open coast
surge levels. These models were used to develop surge time histories due to various
combinations of the meteorological parameters, which define the storms.
Regression analyses were performed to determine the response of the harbor to each
of the parameters while limiting the number of computer runs using the
comprehensive numerical models required.
The WINTSEL and HURSEL models were developed to randomly generate winter
storm and hurricane parameters respectively, and the resulting storm tides. The
storm tides were calculated using simple numerical models based on the regression
analyses performed using the comprehensive numerical models described above.
The numerical models were verified on the basis of historical storm records and the
continuous recording from the National Ocean Survey tidal gage located on
Commonwealth Pier.

21
Stillwater elevations were generated for return periods of 10-, 2-, 1-, and 0.2-
percent-annual-chance. In addition, a number of observations on the character of
the storms and the surge levels affecting Boston were made. In general, it was
found that winter storms were the dominant cause of high water levels on the open
coast and in the harbor. It was also found that waves contribute a significant portion
of the open coast winter storm surge and that these surges can be calculated with
sufficient accuracy using a steady state analysis.
The study indicated that the water levels for the specified return periods are lowest
at the southeastern end of Logan International Airport and increase towards
Dorchester Bay and into the Charles, Neponset, Mystic and Chelsea Rivers. It was
determined that the northeast winds that caused the majority of the storm surges,
forced water into Dorchester Bay and against the coast causing an increase in the
water levels.
Stillwater elevations for the Charles River Basin upstream of the New Charles
River Dam were obtained from a 1979 USACE report (Reference 25).
In Chelsea, storm surge elevations for the Island End River, Mystic River, Boston
Harbor, and the Chelsea River were determined by FEMA. The storm surge
elevations used in this study were obtained from FEMA to insure agreement
between all communities being studied that are adjacent to Boston Harbor.
To calculate the storm surge and total storm tide elevations produced by historic
storms in Revere and Winthrop, it was necessary to determine the storm pressure
and wind fields. A computer model was developed by the study contractor to
simulate these fields based on several, easily obtained, northeaster storm
parameters. A detailed description of this model is presented in the report titled
Development and Verification of a Synthetic Northeaster Model for Coastal Flood
Analysis (Reference 26). A different model was used to simulate the wind and
pressure fields of the hurricanes considered in this analysis (Reference 27).
Synoptic weather maps were searched to determine the northeasters and hurricanes
that could potentially produce significant flooding in the Revere and Winthrop area.
Tidal records from tide gages in the New England areas were examined to verify
which historic storms produced high-water elevations. A total of 165 storms, from
1943 to 1978, were considered in the analysis for flood levels.
The flood levels associated with historic storms were simulated using a modified
version of the FEMA storm surge model (References 28 and 29). Input to the model
consisted of wind and pressure fields generated either by the synthetic northeaster
model or a hurricane wind and pressure field model for each historic storm selected.
The study area was modeled using a square grid of sufficient resolution to
accurately represent the offshore bathymetry and shoreline configuration. The grid
mesh covered an area from Cape Cod Bay to north of Portsmouth, New Hampshire,
including Boston Harbor. Output from the model included the time history of
storm-induced surge elevations in the study area. These elevations were combined

22
with the predicted astronomical tide for the same time period to produce total
stillwater elevations for the communities in the study area. The total still-water
elevation was calibrated using historic tide elevation data at Boston, Massachusetts,
and Portsmouth, New Hampshire. Thus, the historic storm-induced flood levels in
Revere and Winthrop could be simulated for each storm considered in the analysis.
The extent and frequency of recurrence of coastal flooding in Revere were
determined by conducting a frequency analysis of annual maximum tidal heights
along the coastline of Revere. Some historic storm-tide heights, consisting of an
astronomical tide and a storm surge contribution, were determined by the
mathematical simulation of historic northeasters and hurricanes as described above;
others, for which associated storm data were not available, were obtained by a
correlation analysis using tide data from Boston to Portsmouth. The data base at the
Boston gage extended from 1978 discontinuously back to 1848; the shorter record
at Portsmouth was lengthened by a statistical correlation with data at Boston and
Portsmouth. The annual maxima of these reproduced historic stillwater elevations
were fitted with a Pearson Type III distribution. The goodness of fit was tested and
accepted at the 95-percent confidence level.
The analyses of the storm surge elevations for the 10-, 2-, 1-, and 0.2-percent-
annual-chance floods for coastal water reflect the stillwater elevation due to tidal
and wind setup effects. A detailed description of the methodology employed in this
analysis for Revere and Winthrop can be found in the report titled, Determination of
Coastal Storm Tide Levels (Reference 26).
The effects of wave action were also considered in the determination of flood
hazard areas in Revere and Winthrop. Coastal structures which are located above
stillwater flood elevations can still be severely damaged by wave run-up, wave-
induced erosion, and wave-borne debris. For example, during the February 1978 
northeaster, considerable damage among the Massachusetts coast was caused by
wave activity, even though most of the damaged structures were above the high-
water level. The extent of wave run-up past stillwater levels depends greatly on the
wave conditions and local topography.
Wave heights and corresponding wave crest elevation in Revere and Winthrop were
determined using the National Academy of Sciences (NAS) methodology
(Reference 23). The wave run-up was determined using the methodology developed
by Stone and Webster Engineering Corporation for FEMA (Reference 30).
Some areas in Revere are flooded by wave overtopping of seawalls along the coast.
Other areas are flooded by the Saugus and Pines Rivers. Estimating the elevation to
which these areas are flooded is complicated by the following factors: the
overtopping rate is a function of seawall elevation, structure slope, and exposure.
Each of these factors varies along the Revere coastline. Pumping stations and tidal
gates alleviate the flooding problems but, depending on maintenance, they operate
with varying degrees of efficiency.

23
In addition, snow banks may trap floodwaters and intensify flooding. In order to
establish flood elevations in these areas, the USACE made an intensive study of
localized flooding in Revere (Reference 31). The USACE has used engineering
methods to compute seawall overtopping rates and to determine the degree of
flooding from the Saugus and Pines Rivers. The engineering studies were supported
by surveys of the Revere residents concerning flooding from the February 1978 
blizzard. A detailed report of flooding in the Roughans Point area has been
published (Reference 31). The results of the USACE studies are incorporated into
this report. Figure 1, "Area Location Map in Revere," depicts these separate areas
along Broad Sound and Table 8, “Area Location Descriptions in Revere”, describes
each area.
TABLE 8: AREA LOCATION DESCRIPTIONS IN REVERE
Area Description
1 Between North Shore Road and Revere Beach Boulevard and South of
Dix Street
2 Between Revere Beach Boulevard and North Shore Road north of Oak
Island Street
3 Between Boston and Maine Railroad and North Shore Road and
between Revere Street and Bridge Street
4 Between Revere Beach Boulevard and North Shore road and between
Revere Street and Oak Island
5 Between American Legion Highway and Boston & Maine Railroad and
south of Washington Street
6 Between Boston and Maine Railroad and North Shore Road and
between Veterans of Foreign Wars Parkway and Calumet Street
7 Between North Shore Road and Ocean Avenue and between Revere
Street and Beach Street
8 Between North Shore Road and Revere Beach Boulevard and south of
Dix Street
Stillwater flood elevations in the Belle Isle Inlet area in Revere and on the Boston
Harbor side of Winthrop were obtained from the methods and results determined
for the City of Boston (Reference 32).

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25
The stillwater elevations of the selected recurrence intervals are shown in Table 9,
"Summary of Precountywide Stillwater Elevations."
TABLE 9 – SUMMARY OF PRECOUNTYWIDE STILLWATER ELEVATIONS
ELEVATION (feet NAVD 1 )
FLOODING SOURCE AND
LOCATION
10-
PERCENT
2-
PERCENT
1-
PERCENT
0.2-
PERCENT
ATLANTIC OCEAN
Island End River 8.3 9.2 9.5 10.4
Mystic River 8.3 9.1 9.5 10.4
Boston Harbor in the City of
Chelsea
8.2 9.0 9.4 10.2
Chelsea River from Boston
Harbor to Eastern Avenue in
the City of Chelsea
8.3 9.3 9.6 10.5
Chelsea River from Eastern
Avenue to the City of Revere
corporate limits
8.5 9.4 9.8 10.6
Entire Shoreline within the
City of Revere
8.0 8.8 9.2 10.0
At Broad Sound in the Town
of Winthrop
7.9 8.8 9.1 9.9
BELLE ISLE INLET
Entire shoreline 7.7 8.5 8.8 9.6
BOSTON HARBOR
East of Logan Airport 7.7 8.5 8.8 9.6
1 North American Vertical Datum of 1988

26
TABLE 9 – SUMMARY OF PRECOUNTYWIDE STILLWATER ELEVATIONS – cont’d
ELEVATION (feet NAVD 1 )
FLOODING SOURCE AND
LOCATION
10-
PERCENT
2-
PERCENT
1-
PERCENT
0.2-
PERCENT
BOSTON HARBOR –
cont’d
West of Deer Island 7.9 8.8 9.1 9.9
East of Governor's Island 8.0 8.7 9.1 9.9
Northeast of Spectacle Island 8.0 8.9 9.2 10.1
Southeast of Castle Island 8.1 8.9 9.3 10.1
At Long Island 8.1 9.0 9.3 10.2
East of Thompson Island 8.2 9.1 9.4 10.3
Entire shoreline in the Town
of Winthrop
7.7 8.5 8.8 9.6
BOSTON INNER HARBOR
Entire harbor shoreline in the
City of Boston
8.2 9.0 9.4 10.2
BROAD SOUND
Area 1 in Revere 7.0 7.8 8.2 9.4
Area 2 in Revere 5.0 6.0 6.8 8.6
Area 3 in Revere 3.0 4.7 5.8 7.7
1 North American Vertical Datum of 1988

27
TABLE 9 – SUMMARY OF PRECOUNTYWIDE STILLWATER ELEVATIONS – cont’d
ELEVATION (feet NAVD 1 )
FLOODING SOURCE AND
LOCATION
10-
PERCENT
2-
PERCENT
1-
PERCENT
0.2-
PERCENT
BROAD SOUND – cont’d
Area 4 in Revere 4.6 6.8 7.6 9.0
Area 5 in Revere 4.2 4.9 5.4 7.2
Area 6 in Revere 5.0 7.6 8.4 10.0
Area 7 in Revere 6.8 9.6 10.6 12.0
Area 8 in Revere 4.2 5.6 6.2 7.8
CHARLES RIVER BASIN
Immediately upstream of New
Charles River Dam
3.0 3.2 3.5 5.2
CHELSEA RIVER
Immediately upstream of
McArdle Bridge
8.3 9.3 9.6 10.5
Immediately upstream of
Chelsea Street Bridge
8.5 9.4 9.8 10.6
Entire shoreline in City of
Revere
8.5 9.4 9.8 10.6
DORCHESTER BAY
At Old Harbor 8.4 9.3 9.7 10.5
West of Thompson Island 8.6 9.5 9.9 10.7
1 North American Vertical Datum of 1988

28
TABLE 9 – SUMMARY OF PRECOUNTYWIDE STILLWATER ELEVATIONS – cont’d
ELEVATION (feet NAVD 1 )
FLOODING SOURCE AND
LOCATION
10-
PERCENT
2-
PERCENT
1-
PERCENT
0.2-
PERCENT
DORCHESTER BAY –
cont’d
At Neponset River 9.0 10.2 10.6 11.4
LINDEN BROOK
At the confluence with Town
Line Brook
* * 8.2 *
At the upstream corporate
limits
* * 8.2 *
MASSACHUSETTS BAY
At Deer and Lovell Islands 8.0 8.9 9.2 10.1
MYSTIC RIVER
Immediately upstream of
Mystic River Bridge
8.3 9.1 9.5 10.3
PINES RIVER
Entire length within the City
of Revere
7.2 7.9 8.2 9.0
SAUGUS RIVER
At General Edwards Bridge in
the City of Revere
7.2 7.8 8.2 9.0
1 North American Vertical Datum of 1988
*Data Not Available

29
TABLE 9 – SUMMARY OF PRECOUNTYWIDE STILLWATER ELEVATIONS – cont’d
ELEVATION (feet NAVD 1 )
FLOODING SOURCE AND
LOCATION
10-
PERCENT
2-
PERCENT
1-
PERCENT
0.2-
PERCENT
SAUGUS RIVER – cont’d
At confluence of Pines River 7.2 7.8 8.2 9.0
TOWN LINE BROOK
At the confluence with Pines
River
* * 8.2 *
At the upstream Revere
corporate limits
* * 8.2 *
1 North American Vertical Datum of 1988
*Data Not Available
For Boston, Revere, and Winthrop, the methodology for analyzing wave run-up was
developed by Stone and Webster Engineering Corporation (Reference 33). The
wave run-up computer program operates using an ensemble of deepwater wave
heights, Hi, the stillwater elevation, S, a wave period, Ts, and beach slope, m. For
the City of Boston, wave heights range from 2 feet up to the significant wave height
of 19 feet; the wave period equals 7 and 14 seconds. For Revere, wave heights
range from 5 feet up to the significant wave height of 30 feet; the wave period
equals 14 seconds.
These concepts and equations were used to compute wave envelope elevations
associated with the 1-percent-annual-chance storm surge. Accurate topographic
land-use and land-cover data are required for the coastal analyses. Maps of the
Boston study area, at a scale of 1:1,200 with a contour interval of 5 feet were used
for the topographic data (Reference 34). The land-use and land-cover data were
obtained by field surveys. Maps of the study area, at a scale of 1:4,800 in Revere
and 1:2,400 in Winthrop, with a contour interval of 5 feet, were used for the
topographic data (Reference 35). The land-use and land-cover data were obtained
by field surveys.
Wave heights and wave run-up were computed along transects located
perpendicular to the average mean shoreline. The transects were located with
consideration given to the physical and cultural characteristics of the land so that

30
they would closely represent conditions in their locality. Transects were spaced
close together in areas of complex topography and dense development. In areas
having more uniform characteristics, transects were spaced at larger intervals. It
was also necessary to locate transects in areas where unique flooding existed and in
areas where computed wave heights varied significantly between adjacent transects.
During the course of the wave run-up analysis, shallow flooding areas were
determined and delineated due to overland flow and the topography of the area.
Along each transect, wave envelope elevations were computed considering the
combined effects of changes in ground elevation, vegetation, and physical features.
Between transects, elevations were interpolated using topographic maps, land-use
and land cover data, and engineering judgment to determine the real extent of
flooding. The results of the calculations are accurate until local topography,
vegetation, or cultural development within the community undergoes any major
changes.
Transect Descriptions for precountywide coastal analyses are shown in Table 10
below and have been re-numbered to conform to countywide standards.
TABLE 10 - PRECOUNTYWIDE TRANSECT DESCRIPTIONS
TRANSECT LOCATION
1 From Rice Avenue, extending southeast into Broad Sound
2 From Lynnway Boulevard, extending southeast into Broad Sound
3 From just south of Essex County/Suffolk County boundary,
extending southeast into Broad Sound
4 Extending east-southeast along Argyles Street, into Broad Sound
5 North Shore Road, just north of Butler Circle, extending eastward
into Broad Sound
6 From railroad tracks just east of Garfield Jr. High School, extending
east-northeast into Broad Sound

31
TABLE 10 - PRECOUNTYWIDE TRANSECT DESCRIPTIONS – cont’d
TRANSECT LOCATION
7 From northeast of Henry Street and Dolphin Avenue, extending
eastward into Broad Sound
8 From Crescent Avenue, extending east-northeast into Broad Sound
9 From Highland Avenue and Seawall Avenue, extending north into
Broad Sound
10 From the Radio Tower in the northeast area of Winthrop, extending
east into Broad Sound
11 From southwest of Crest Avenue and Hutchinson Street, extending
eastward into Broad Sound
12 Following Wave Way, extending into Broad Sound
13 From Shirley Street at Irwin Street, extending northeast into Broad
Sound
14 From Park Avenue and Beacon Street, extending east-northeast into
Broad Sound
15 From Prospect Avenue, extending southeast into Broad Sound
16 From Hale Avenue and Undine Avenue, extending east-northeast
towards Broad Sound
17 From House of Correction Cemetery, extending northeast into Broad
Sound
18 From just south of Deer Island Reservoir, extending east into Broad
Sound
19 Governors Island, extending east-southeast into Boston Harbor

32
TABLE 10 - PRECOUNTYWIDE TRANSECT DESCRIPTIONS – cont’d
TRANSECT LOCATION
20 From Sumner Tunnel near North Street, extending southeast into
Boston Inner Harbor
21 From Castle Island's Fort Independence, extending east into Boston
Harbor
22 From Marine Park, extending east-southeast past Pleasure Bay and
into Boston Harbor
23 From Swallow Street, extending southeast into Dorchester Bay and
out to Thompson Island
24 From west side of Columbus Park, extending east-southeast into
Dorchester Bay
25 From Dorchester Ave at Linden Street, extending east into Dorchester
Bay
26 From Spectacle Island, extending northeast into Boston Harbor
27 From Long Island Head, extending northeast into Massachusetts Bay
28 From Lovell Island, extending northeast into Massachusetts Bay
29 From Georges Island, extending northeast into Massachusetts Bay

33
In Table 11, "Summary of Precountywide Coastal Analyses," the flood hazard
zones and base flood elevations for each flooding source is provided, along with the
1-percent-annual-chance stillwater elevation.
TABLE _11_ - SUMMARY OF PRECOUNTYWIDE COASTAL ANALYSES
STILLWATER ELEVATIONS (feet NAVD 1 )
FLOODING SOURCE
10-
PERCENT-
ANNUAL-
CHANCE
2-
PERCENT-
ANNUAL-
CHANCE
1-
PERCENT-
ANNUAL-
CHANCE
0.2-
PERCENT-
ANNUAL-
CHANCE ZONE
BASE
FLOOD
ELEVATION
(feet NAVD 1 )
ATLANTIC OCEAN
City of Revere 7.2 * 9.2 * VE 11.2-19.2
AE 9.2-12.2
BELLE ISLE INLET
City of Revere 7.7 * 8.8 * AE 9.2
BOSTON INNER HARBOR
City of Boston 8.2 * 9.4 * VE 11.2-13.2
AE 9.2-11.2
AE 9.2-10.2
BOSTON HARBOR
City of Boston 7.7 * 8.8 * VE 11.2-23.2
AE 9.2-11.2
AE 8.7
7.9 * 9.1 * VE 11.2
AE 9.2-11.2
8 * 9.1 * VE 11.2-14.2
AE 9.2-11.2
1 North American Vertical Datum of 1988
*Data not available

34
TABLE _11_ - SUMMARY OF PRECOUNTYWIDE COASTAL ANALYSES – cont’d
STILLWATER ELEVATIONS (feet NAVD 1 )
FLOODING SOURCE
10-
PERCENT-
ANNUAL-
CHANCE
2-
PERCENT-
ANNUAL-
CHANCE
1-
PERCENT-
ANNUAL-
CHANCE
0.2-
PERCENT-
ANNUAL-
CHANCE ZONE
BASE
FLOOD
ELEVATION
(feet NAVD 1 )
BOSTON HARBOR – cont’d
City of Boston 8 * 9.2 * VE 13.2-27.2
AE 9.2
8.1 * 9.3 * VE 13.2-20.2
VE 11.2-14.2
AE 9.2-11.2
AE 9.2-20.2
8.1 * 9.3 * VE 12.2-24.2
VE 11.2-13.2
AE 9.2-11.2
AE 9.2
8.2 * 9.4 * VE 14.2-24.2
VE 11.2-13.2
AE 9.2-11.2
BROAD SOUND
City of Revere
Area 1 7 * 8.2 * AE 8.2
Area 2 5 * 6.8 * AE 7.2
Area 3 3 * 5.8 * AE 6.2
Area 4 4.6 * 7.6 * AE 7.2
1 North American Vertical Datum of 1988
*Data not available

35
TABLE _11_ - SUMMARY OF PRECOUNTYWIDE COASTAL ANALYSES – cont’d
STILLWATER ELEVATIONS (feet NAVD 1 )
FLOODING SOURCE
10-
PERCENT-
ANNUAL-
CHANCE
2-
PERCENT-
ANNUAL-
CHANCE
1-
PERCENT-
ANNUAL-
CHANCE
0.2-
PERCENT-
ANNUAL-
CHANCE ZONE
BASE
FLOOD
ELEVATION
(feet NAVD 1 )
BROAD SOUND – cont’d
City of Revere –cont’d
Area 5 4.2 * 5.4 * AE 5.2
Area 6 5 * 8.4 * AE 8.2
Area 7 6.8 * 10.6 * AE 10.2
Area 8 4.2 * 6.2 * AE 6.2
CHARLES RIVER BASIN
City of Boston 3 * 3.5 * AE 3.7
CHELSEA RIVER
City of Boston 8.3 * 9.6 * AE 9.7
City of Revere 8.5 * 9.8 * AE 9.7-10.2
DORCHESTER BAY
City of Boston 8.4 * 9.7 * VE 16.2-21.2
VE 12.2-14.2
AE 10.2-14.2
AE 9.5
8.6 * 9.9 * VE 14.2-24.2
AE 9.7
1 North American Vertical Datum of 1988
*Data not available

36
TABLE _11_ - SUMMARY OF PRECOUNTYWIDE COASTAL ANALYSES – cont’d
STILLWATER ELEVATIONS (feet NAVD 1 )
FLOODING SOURCE
10-
PERCENT-
ANNUAL-
CHANCE
2-
PERCENT-
ANNUAL-
CHANCE
1-
PERCENT-
ANNUAL-
CHANCE
0.2-
PERCENT-
ANNUAL-
CHANCE ZONE
BASE
FLOOD
ELEVATION
(feet NAVD 1 )
DORCHESTER BAY – cont’d
City of Boston – cont’d 9 * 10.6 * VE 13.2-15.2
AE 11.2-12.2
AE 10.2-24.2
AE 10.7
MASSACHUSETTS BAY
City of Boston 8 * 9.2 * VE 11.2-28.2
VE 11.2-14.2
AE 9.2-11.2
AE 9.2-14.2
MYSTIC RIVER
City of Boston 8.3 * 9.5 * AE 9.7
PINES RIVER
City of Revere 7.2 * 8.2 * AE 8.2
SAUGUS RIVER
City of Revere 7.2 * 8.2 * AE 9.2
1 North American Vertical Datum of 1988
*Data not available
Due to map scale limitations, base flood elevations shown on the FIRM represent
average elevations for the zones depicted.

37
During the course of the wave run-up analysis, shallow flooding areas were
determined and delineated due to overland flow and the topography of the area.
Countywide Analyses
No new Coastal Analyses were performed for this countywide FIS.
The transect schematic represents a sample transect that illustrates the relationship
between the stillwater elevation , the wave crest elevation, the ground elevation
profile, and the location of the A/V zone boundary. Figure 2, “Transect Schematic.” 
Figure 2. Transect Schematic 
3.4 Vertical Datum
All FIS reports and FIRMs are referenced to a specific vertical datum. The vertical
datum provides a starting point against which flood, ground, and structure
elevations can be referenced and compared. Until recently, the standard vertical
datum used for newly created or revised FIS reports and FIRMs was the National
Geodetic Vertical Datum of 1929 (NGVD). With the completion of the North
American Vertical Datum of 1988 (NAVD), many FIS reports and FIRMs are now
prepared using NAVD as the referenced vertical datum.

38
All flood elevations shown in this FIS report and on the FIRM are referenced to the
NAVD 88. These flood elevations must be compared to structure and ground
elevations referenced to the same vertical datum. Ground, structure, and flood
elevations may be compared and/or referenced to NGVD 29 by applying a standard
conversion factor. The conversion factor from NGVD 29 to NAVD 88 is -0.8,
and from NAVD 88 to NGVD 29 is +0.8. 
For information regarding conversion between the NGVD and NAVD, visit the
National Geodetic Survey website at www.ngs.noaa.gov, or contact the National
Geodetic Survey at the following address:
Vertical Network Branch, N/CG13
National Geodetic Survey, NOAA
Silver Spring Metro Center 3
1315 East-West Highway
Silver Spring, Maryland 20910
(301) 713-3191
Temporary vertical monuments are often established during the preparation of a
flood hazard analysis for the purpose of establishing local vertical control.
Although these monuments are not shown on the FIRM, they may be found in the
Technical Support Data Notebook associated with the FIS report and FIRM for this
county. Interested individuals may contact FEMA to access these data.
The BFEs shown on the FIRM represent whole-foot rounded values. For example, a
BFE of 102.4 will appear as 102 on the FIRM and 102.6 will appear as 103.
Therefore, users that wish to convert the elevations in this FIS to NGVD 29 should
apply the stated conversion factor to elevations shown on the Flood Profiles and
supporting data tables in the FIS report, which are shown at a minimum to the
nearest 0.1 foot.
To obtain current elevation, description, and/or location information for
benchmarks shown on this map, please contact the Information Services Branch of
the NGS at (301) 713-3242, or visit their website at www.ngs.noaa.gov.
4.0 FLOODPLAIN MANAGEMENT APPLICATIONS
The National Flood Insurance Program encourages State and local governments to adopt
sound floodplain management programs. To assist in this endeavor, each FIS report
provides 1-percent-annual-chance floodplain data, which may include a combination of the
following: 10-, 2-, 1-, and 0.2-percent-annual-chance flood elevations; delineations of the

39
1- and 0.2-percent-annual-chance floodplains; and a 1-percent-annual-chance floodway.
This information is presented on the FIRM and in many components of the FIS report,
including Flood Profiles, Floodway Data tables, and Summary of Stillwater Elevation
tables. Users should reference the data presented in the FIS report as well as additional
information that may be available at the local community map repository before making
flood elevation and/or floodplain boundary determinations.
4.1 Floodplain Boundaries
To provide a national standard without regional discrimination, the
1-percent-annual-chance flood has been adopted by FEMA as the base flood for
floodplain management purposes. The 0.2-percent-annual-chance flood is
employed to indicate additional areas of flood risk in the community. For each
stream studied by detailed methods, the 1- and 0.2-percent-annual-chance
floodplain boundaries have been delineated using topographic maps (Reference 34).
Between cross sections in Boston, the boundaries were interpolated using
topographic maps at a scale of 1"=400’ with a contour interval of 5 feet (Reference
7).
For Boston’s tidal areas without wave action, the 1- and 0.2-percent-annual-chance
floodplain boundaries were delineated using the topographic maps at a scale of
1:1,200 with a contour interval of 5 feet (Reference 34). For Winthrop’s tidal areas
without wave action, the 1- and 0.2-percent-annual-chance boundaries were
delineated using topographic maps at a scale of 1:2,400 with a contour interval of 5
feet (Reference 35).
For Boston’s and Winthrop's tidal areas with wave action, the flood boundaries
were delineated using the elevations determined at each transect; between transects,
the boundaries were interpolated using engineering judgment, land-cover data, and
the topographic maps referenced above. The 1-percent-annual-chance floodplain
was divided into whole-foot elevation zones based on the average wave envelope
elevation in that zone. Where the map scale did not permit these zones to be
delineated at one foot intervals, larger increments were used (Reference 35).
In the 1984 Winthrop FIS, the boundaries were interpolated between cross-sections,
using topographic maps at a scale of 1:4,800 with a contour interval of 5 feet
(Reference 35).
Flood boundaries for areas in Boston studied by approximate methods were
obtained from the previous October 1, 1983 FIS for the City of Boston (Reference
36). For areas in Chelsea studied by approximate methods, the boundary of the 1-
percent-annual-chance flood was delineated using USGS topographic maps and a
drainage study prepared for the Massachusetts Department of Public Works
(References 13 and 37). In the 1984 Revere FIS, for areas of flooding studied by
approximate methods, the 1-percent-annual-chance flood boundary was delineated
using the topographic maps referenced above. In the Revere August 2, 2002

40
revision, an area of approximate flooding in the northeast comer of Revere was
delineated in order to match the approximate flooding in the contiguous community
of the City of Malden in Middlesex County. The delineation involved the use of
topographic maps at a scale of 1:25,000 and a contour interval of 10 feet (Reference
38)
The boundaries of the 1-percent-annual-chance flood for Town Line Brook and
Linden Brook in Revere have been delineated using the flood elevation of 9 ft,
determined for the area downstream of U.S. Route 1. This was an elevation agreed
upon by FEMA, Dewberry & Davis LLC, and Roald Haestad, Inc., after Haestad,
Inc., found a flood control dike that did not meet FEMA standards. The dike was
considered to be bypassed and thus the area upstream of U.S. Route 1 would be
affected by coastal flooding. This area was therefore delineated to the same
elevation shown for the area downstream of U.S. Route 1, which is 9 ft. The
boundaries were delineated using topographic mapping at a scale of 1:480 with a
contour interval of 2 feet and at a scale of 1:4,800 with a contour interval of 4 feet
(References 39 and 40), and using construction drawings for developments that
were constructed after the mapping was completed
The 1- and 0.2-percent-annual-chance floodplain boundaries are shown on the
FIRM. On this map, the 1-percent-annual-chance floodplain boundary corresponds
to the boundary of the areas of special flood hazards (Zones A, AE, and VE), and
the 0.2-percent-annual-chance floodplain boundary corresponds to the boundary of
areas of moderate flood hazards. In cases where the 1- and
0.2-percent-annual-chance floodplain boundaries are close together, only the
1-percent-annual-chance floodplain boundary has been shown. Small areas within
the floodplain boundaries may lie above the flood elevations, but cannot be shown
due to limitations of the map scale and/or lack of detailed topographic data.
For the streams studied by approximate methods, only the 1-percent-annual-chance
floodplain boundary is shown on the FIRM.
4.2 Floodways
Encroachment on floodplains, such as structures and fill, reduces flood-carrying
capacity, increases flood heights and velocities, and increases flood hazards in areas
beyond the encroachment itself. One aspect of floodplain management involves
balancing the economic gain from floodplain development against the resulting
increase in flood hazard. For purposes of the NFIP, a floodway is used as a tool to
assist local communities in this aspect of floodplain management. Under this
concept, the area of the 1-percent-annual-chance floodplain is divided into a
floodway and a floodway fringe. The floodway is the channel of a stream, plus any
adjacent floodplain areas, that must be kept free of encroachment so that the base
flood can be carried without substantial increases in flood heights. Minimum
Federal standards limit such increases to 1 foot, provided that hazardous velocities
are not produced. The floodways in this study are presented to local agencies as
minimum standards that can be adopted directly or that can be used as a basis for

41
additional floodway studies.
The floodway presented in this study was computed on the basis of equal
conveyance reduction from each side of the floodplain. Floodway widths were
computed at cross sections. Between cross sections, the boundaries were
interpolated. In cases where the floodway and 1-percent-annual-chance floodplain
boundaries are either close together or collinear, only the floodway boundary has
been shown. Portions of the floodway widths of Chelsea and Revere’s Mill Creek
extend beyond the corporate limits. The results of the floodway computations are
tabulated at selected cross sections for each stream segment for which a floodway is
computed (See Table 12).
Encroachment into areas subject to inundation by floodwaters having hazardous
velocities aggravates the risk of flood damage, and heightens potential flood
hazards by further increasing velocities. A listing of stream velocities at selected
cross sections is provided in Table 12, "Floodway Data." To reduce the risk of
property damage in areas where the stream velocities are high, the community may
wish to restrict development in areas outside the floodway.
Floodway encroachments were not determined for the Neponset River. This river is
located entirely within the Neponset River Reservations. In analyzing this portion
of the river using the HEC-2 program, the selected effective flow areas of the river
were well inside the boundaries of the reservation. The computer was programmed
not to recognize the areas of slack water beyond the effective flow limits. Therefore
any encroachment up to the reservation boundary will have no appreciable effect on
the river velocity or water-surface elevation. However, almost the entire land area
from the banks of the Neponset River up to the 1-percent-annual-chance flood
boundary has been subjected to an Order of Restriction in accordance with Chapter
131, Section 40A, of the General Laws of the Commonwealth of Massachusetts.
Under this law, any permanent wetland so designated by the state cannot be built
upon in any way.
The identical situation exists along the Charles River. The restricted wetlands
almost completely occupy the areas inundated by the 1-percent-annual-chance
flood. The areas not covered are so small that the delineation of a floodway would
be useless as a functional tool to be used by the community for its floodplain
management program. Therefore, no floodway has been defined for both the
Neponset and Charles Rivers. Additionally, floodways were not computed for
Muddy River and Stony Brook.
The area between the floodway and 1-percent-annual-chance floodplain boundaries
is termed the floodway fringe. The floodway fringe encompasses the portion of the
floodplain that could be completely obstructed without increasing the water-surface
elevation of the 1-percent-annual-chance flood by more than 1.0 foot at any point.
Typical relationships between the floodway and the floodway fringe and their
significance to floodplain development are shown in Figure 3, “Floodway
Schematic”.

42
In Chelsea and Revere, near the mouths of streams studied in detail, floodway
computations were made without regard to flood elevations on the receiving water
body. Therefore, "Without Floodway" elevations presented in Table 12 for certain
downstream cross sections of Mill Creek are lower than the regulatory flood
elevations in that area, which must take into account the 1-percent-annual-chance
flooding due to backwater from other sources.
Additionally, no floodways were computed for the Town of Winthrop and no
floodways extend beyond the county boundary.
. 
Figure 3. Floodway Schematic

A 502 310 / 210 2 2561 0.9 9.8 4.1 3 5.1 1.0
B 1447 140 / 40 2 753 3.1 9.8 4.1 3 5.1 1.0
C 2777 120 / 100 2 951 2.4 12.5 12.5 12.5 0.0
D 3305 80 / 60 2 897 2.6 12.6 12.6 12.6 0.0
E 4572 90 / 20 2 786 2.9 13.0 13.0 13.5 0.5
1
2
3 
CROSS
SECTION
ALL JURISDICTIONS
WIDTH
(FEET)
MEAN
VELOCITY
(FEET PER SECOND) 
FEET ABOVE CONFLUENCE WITH CHELSEA RIVER
WIDTH/WIDTH WITHIN SUFFOLK COUNTY
ELEVATION COMPUTED WITHOUT CONSIDERATION OF TIDAL FLOODING FROM CHELSEA RIVER 
REGULATORY WITHOUT
FLOODWAY
WITH
FLOODWAY INCREASE 
SUFFOLK COUNTY, MA
TABLE 12 MILL CREEK
BASE FLOOD
WATER SURFACE ELEVATION
(FEET NAVD) 
FLOODWAY DATA 
FLOODWAY
FEDERAL EMERGENCY MANAGEMENT AGENCY
SECTION
AREA
(SQUARE FEET)
FLOODING SOURCE
DISTANCE 1

A 300 45 187 7.8 43.1 43.1 43.1 0.0
B 750 52 324 4.5 43.4 43.4 43.4 0.0
C 950 50 322 4.6 43.6 43.6 43.6 0.0
D 1,100 64 414 3.6 43.8 43.8 43.8 0.0
E 1,233 64 415 3.5 43.8 43.8 43.8 0.0
F 1,600 60 321 4.6 43.9 43.9 43.9 0.0
G 2,050 60 379 3.9 44.6 44.6 44.8 0.2
H 2,725 153 646 2.3 45.6 45.6 45.8 0.2
I 4,095 84 186 7.9 48.5 48.5 48.5 0.0
J 5,000 200 1445 1.0 49.9 49.9 49.9 0.0
K 6,000 147 1036 1.4 49.9 49.9 49.9 0.0
L 7,130 102 728 2.0 50.1 50.1 50.2 0.1
1 
CROSS
SECTION
ALL JURISDICTIONS
WIDTH
(FEET)
MEAN
VELOCITY
(FEET PER SECOND) 
FEET ABOVE CONFLUENCE WITH NEPONSET RIVER 
SUFFOLK COUNTY, MA 
REGULATORY WITHOUT
FLOODWAY
WITH
FLOODWAY INCREASE 
TABLE 12 MOTHER BROOK
BASE FLOOD
WATER SURFACE ELEVATION
(FEET NAVD) 
FLOODWAY DATA 
FLOODWAY
FEDERAL EMERGENCY MANAGEMENT AGENCY
SECTION
AREA
(SQUARE FEET)
FLOODING SOURCE
DISTANCE 1

45
5.0 INSURANCE APPLICATIONS
For flood insurance rating purposes, flood insurance zone designations are assigned to a
community based on the results of the engineering analyses. The zones are as follows:
Zone A
Zone A is the flood insurance rate zone that corresponds to the 1-percent annual
chance floodplains that are determined in the FIS by approximate methods.
Because detailed hydraulic analyses are not performed for such areas, no base (1-
percent-annual-chance) flood elevations (BFEs) or depths are shown within this
zone.
Zone AE
Zone AE is the flood insurance rate zone that corresponds to the 1-percent annual
chance floodplains that are determined in the FIS by detailed methods. In most
instances, whole-foot BFEs derived from the detailed hydraulic analyses are shown
at selected intervals within this zone.
Zone AH
Zone AH is the flood insurance rate zone that corresponds to areas of
1-percent-annual-chance shallow flooding (usually areas of ponding) where average
depths are between 1 and 3 feet. Whole-foot BFEs derived from the detailed
hydraulic analyses are shown at selected intervals within this zone.
Zone AO
Special Flood Hazard Areas inundated by types of 1-percent-annual-chance flood
shallow flooding, where depths are between 1 and 3 feet. Depths are shown within
this zone
Zone V
Zone V is the flood insurance rate zone that corresponds to the 1-percent annual
chance coastal floodplains that have additional hazards associated with storm
waves. Because approximate hydraulic analyses are performed for such areas, no
BFEs are shown within this zone.
Zone VE
Zone VE is the flood insurance rate zone that corresponds to the 1-percent annual
chance coastal floodplains that have additional hazards associated with storm
waves. Whole-foot BFEs derived from the detailed hydraulic analyses are shown at
selected intervals within this zone.

46
Zone X
Zone X is the flood insurance rate zone that corresponds to areas outside the
500-year floodplain, areas within the 0.2-percent annual chance floodplain, and
areas of 1-percent annual chance flooding where average depths are less than 1 foot,
areas of 1-percent annual chance flooding where the contributing drainage area is
less than 1 square mile, and areas protected from the 1-percent annual chance flood
by levees. No BFEs or depths are shown within this zone.
6.0 FLOOD INSURANCE RATE MAP
The FIRM is designed for flood insurance and floodplain management applications.
For flood insurance applications, the map designates flood insurance rate zones as
described in Section 5.0 and, in the 1-percent-annual-chance floodplains that were studied
by detailed methods, shows selected whole-foot BFEs or average depths. Insurance agents
use zones and BFEs in conjunction with information on structures and their contents to
assign premium rates for flood insurance policies.
For floodplain management applications, the map shows by tints, screens, and symbols, the
1- and 0.2-percent-annual-chance floodplains, floodways, and the locations of selected
cross sections used in the hydraulic analyses and floodway computations.
The countywide FIRM presents flooding information for the entire geographic area of
Suffolk County. Previously, FIRMs were prepared for each incorporated community and
the unincorporated areas of the County identified as flood-prone. This countywide FIRM
also includes flood-hazard information that was presented separately on Flood Boundary
and Floodway Maps (FBFMs), where applicable. Historical data relating to the maps
prepared for each community are presented in Table 13, “Community Map History.”

COMMUNITY NAME INITIAL IDENTIFICATION
FLOOD HAZARD
BOUNDARY MAP
REVISION DATE(S)
FLOOD INSURANCE
RATE MAP
EFFECTIVE DATE
FLOOD INSURANCE
RATE MAP
REVISION DATE(S) 
Boston, City of
Chelsea, City of
Revere, City of
Winthrop, Town of
November 22, 1974
June 7, 1974
June 28, 1974
June 28, 1974
February 11, 1977
June 7, 1977
December 27, 1974
February 18, 1977
None
April 1, 1982
August 2, 1982
October 16, 1984
October 8, 1976
October 1, 1983
November 2, 1990
July 2, 1992
N/A
August 20, 2002
August 15, 1984
July 2, 1992
T
A
B
L
E
13 
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
(ALL JURISDICTIONS)
COMMUNITY MAP HISTORY

48
7.0 OTHER STUDIES
Information pertaining to revised and unrevised flood hazards for each jurisdiction within
Suffolk County has been compiled in this FIS. Therefore, this FIS supersedes all previously
printed FIS reports, FIRMs, and/or FHBMs for all of the incorporated jurisdictions within
Suffolk County.
Suffolk County is bordered by Essex County, MA to the north, Norfolk County, MA to the
south, and Middlesex County, MA to the west. At the time of this revision, all of these
counties were either undergoing revisions or were known to have revisions in the future.
They will all be in agreement with this countywide FIS.
Due to its highly developed state, the City of Boston has been subject to numerous flood-
related studies as a result of construction proposals, waterway improvements, water quality
assessments and flood plain management studies.
The Charles River and the lower Charles River Basin have been extensively studied by the
USACE, SCS, and C. E. Maguire, Inc., as a result of its serious flood problems (References
8, 10 and 18). Elevations for the floods of the selected recurrence intervals, discharge data,
inflow hydrographs and other pertinent hydrologic and hydraulic data were adopted into
this countywide FIS, as were flood elevations for the Muddy River.
Flood elevations for the Neponset River and Mother Brook were coordinated with detailed
studies done in 1971 and 1973 (References 17 and 41). Elevations were coordinated with
the FISs of the surrounding Cities of Quincy and Newton, and Towns of Milton, Dedham,
Needham, Brookline, and Winthrop (References 9, 11, and 42-46).
Tidal elevations for Boston Harbor was coordinated with the frequency curve developed by
the USACE for the tidal gage at Commonwealth Pier, and were checked with historical
elevations recorded by the USGS during the flood of February 1978 (Reference 25).
The Flood Hazard Boundary and Flood Insurance Rate Maps for the 1983 Boston FIS were
prepared on topographic maps of Boston provided by the Boston Redevelopment Authority
(Reference 34). Although these represented the best available maps at the time, they were
15 years old, and a number of areas may have been out of date, causing inaccuracies in the
flood boundary delineations. The analyses prepared for the 1990 Boston FIS, and included
as part of this countywide study, included a more detailed and up-to-date coastal analysis
than the FISs for Milton and Quincy (Norfolk County) Therefore, BFEs and transect data
computed and shown in this countywide study may differ from the results of those previous
studies. Because of the increased pumping capacity of the New Charles River Dam, the
flood elevations for the Charles River Basin included in this study are lower than those
computed in the Newton FIS (Middlesex County). Also, the flood boundaries delineated
for the Charles River at the Boston-Newton corporate limits in this countywide study do
not agree with those shown in the Newton FIS because more detailed topographic maps
were used in this study than in the previously published study. Flood elevations for Mother
Brook at the Boston-Dedham corporate limits are slightly higher in this study than in the
Dedham FIS because of more up-to-date hydraulic analyses.

49
In Chelsea, a drainage study of Mill Creek was performed for the Massachusetts
Department of Public Works in 1975 (Reference 13). The purpose of the study was to
analyze the causes of frequent flooding at the housing project near Mill Creek upstream of
U. S. Route 1. Discharges related to the drainage study were compared to discharges
developed by a Massachusetts regional equation (Reference 47). The differences between
the values determined by the two methods were so great that a third method was applied. A
SCS method derived for small watersheds was incorporated to develop additional flow
values (Reference 48). The 1-percent-annual-chance discharge determined by the SCS
method was very similar to that developed for the drainage study. As the SCS method may
not be appropriate for such extensively urbanized watersheds, the values from the drainage
study were adopted for the hydraulic analysis in this countywide study.
In Revere, the flood water-surface elevation selected for the remapping of Town Line
Brook does impact the contiguous communities of Malden and Everett (Middlesex
County). The flood limits in both of the contiguous communities have also been remapped
under the 2002 Revere FIS revision.
Using National Ocean Survey tide gage data, the USACE has predicted 10-, 2, 1, and 0.2-
percent-annual-chance flood levels at Boston, Massachusetts, and Portsmouth, New
Hampshire. The predictions compare favorably with flood levels determined for Winthrop
in view of the distance between Winthrop and the National Ocean Survey gaging stations.
8.0 LOCATION OF DATA
Information concerning the pertinent data used in the preparation of this study can be
obtained by contacting FEMA Region I, 99 High Street, 6th Floor, Boston, MA 02110.
9.0 BIBLIOGRAPHY AND REFERENCES
1. U.S. Census Bureau, 2000 Census of Population and Housing, Population and Housing
Unit Count, PHC-3-23, Massachusetts, Washington, D.C., 2003
2. National Weather Service, Taunton. Boston Daily Normals. 2006.
3. Weatherbase. Historical Weather for Boston, Massachusetts, United States of America.
2008.
4. City of Boston Film Bureau. Weather. 2007.
5. Massachusetts Agricultural Experiment Station, Remote Sensing 20 Years of Change in
Suffolk and Norfolk Counties, Massachusetts, 1951-1971 by William P. McConnell,
August 1974.
6. U.S. Army Corps of Engineers, North Atlantic Division. National Shoreline Study.
Regional Inventory Report, North Atlantic Region, Volume I. New York, 1971.

50
7. Water Resources Council, A Uniform Technique for Determining Flood Flow Frequency,
Bulletin 15, Washington, D. C., December 1967.
8. U.S. Army Corps of Engineers, New England District, Interim Report on the Charles River
for Flood Control and Navigation; Lower Charles River, Waltham, Massachusetts, May
1968.
9. U.S. Department of Housing and Urban Development, Federal Insurance Administration,
Flood Insurance Study, Town of Dedham, Norfolk County, Massachusetts, Washington,
D.C., May 1977.
10. U.S. Army Corps of Engineers, New England District, Charles River Study, Appendices D
and H, Waltham, Massachusetts, May 1972.
11. U.S. Department of Housing and Urban Development, Federal Insurance Administration,
Flood Insurance Study Town of Milton, Norfolk County, Massachusetts, Washington,
D.C., March 1977.
12. U.S. Department of the Interior, Geological Survey, Coastal Flood of February 7, 1978, in
Maine, Massachusetts, and New Hampshire, No. 79-61, Boston, Massachusetts, 1979.
13. Congdon, Gurney and Towle, Inc., prepared for the Massachusetts Department of Public
Works, Mill Creek Drainage Study, Boston, Massachusetts, 1975.
14. Stone & Webster Engineering Corporation, Development and Verification of a Synthetic
Northeaster Model for Coastal Flood Analysis, Boston, Massachusetts, October 1979
15. Moore Survey and Mapping Corporation of Shrewsbury, Massachusetts, Topographic
Maps compiled by photogrammetric methods, Scale 1"=400’, Contour Interval 5 Feet:
Chelsea, Massachusetts, 1977.
16. U.S. Army Corps of Engineers, Hydrologic Engineering Center, HEC-2 Water Surface
Profiles, Generalized Computer Program, Davis, California, October 1973.
17. Anderson-Nichols Co., Neponset River Basin Flood Plain and Wetland Encroachment
Study, Boston, Massachusetts, April 1971.
18. C.E. Maguire, Inc., The Proposed Charles River Project, Waltham, Massachusetts, October
1974.
19. U.S. Army Corps of Engineers, New England District, Charles River Locks and Dam
(Design Memorandum No. 1) Hydrology and Tidal Hydraulics, Waltham, Massachusetts,
May 1971.

51
20. U.S. Department of the Interior, Geological Survey, Water Resources Investigations 79-61,
Coastal Flood of February 7, 1978, Maine, Massachusetts, and New Hampshire, Boston,
Massachusetts, 1979.
21. Federal Disaster Assistance Administration, Damage Survey Reports & the Town of
Winthrop, Massachusetts, Washington, D.C., February 1978.
22. U.S. Army Corps of Engineers, Galveston District, Guidelines for Identifying Coastal High
Hazard Zones Galveston, Texas, June 1975.
23. National Academy of Sciences, Methodology for Calculating Wave Action Effects
Associated with Storm Surges, Washington, D. C., 1977.
24. Harris-Toups Associates, Flood Insurance Study, Coastal Flooding Analysis, Boston,
Massachusetts, Lake Success, New York, December 1977.
25. U.S. Army Corps of Engineers, New England District, Frequency of Tidal Flooding at
Boston Harbor, Waltham, Massachusetts, April 1979.
26. Stone and Webster Engineering Corporation. Development and Verification of a Synthetic
Northeaster Model for Coastal Flood Analysis. Boston, Massachusetts. October 1978,
27. Stone and Webster Engineering Corporation. Two-Dimensional Coastal Storm Surge
Model, SWECO 7501-NP-A. Boston, Massachusetts. July 1977.
28. Tetra Tech, Inc. Coastal Flooding Handbook, Parts I and II. Pasadena, California. May
1977.
29. Stone and Webster Engineering Corporation. Determination of Coastal Storm Tide Levels.
Boston, Massachusetts. October 1978.
30. Stone and Webster Engineering Corporation. Manual for Wave Runup Analysis, Coastal
Flood Insurance Studies. Boston, Massachusetts. November 1981.
31. U.S. Army Corps of Engineers, New England Division. Roughans Point, Revere,
Massachusetts, Coastal Flood Protection Study, Volume I and II. Waltham, Massachusetts.
December 1982.
32. Federal Emergency Management Agency, Federal Insurance Administration, Flood
Insurance Study, City of Boston, Suffolk County, Massachusetts, Washington, D.C.,
October 1, 1981.
33. Stone and Webster Engineering Corporation, Manual for Wave Runup Analysis, Coastal
Flood Insurance Studies, Boston, Massachusetts, November 1981.
34. Boston Redevelopment Authority, Topographic Mapping, City of Boston, Scale 1:1,200,
Contour Interval 5 Feet, Boston, Massachusetts, 1967.

52
35. James W. Sewall Co., of Old Town, Maine, Topographic Maps, Scale 1: 2,400, Contour
Interval 5 Feet: Winthrop, Massachusetts, December 1978.
36. Federal Emergency Management Agency, Flood Insurance Study, City of Boston, Suffolk
County, Massachusetts, Washington, D. C., October 1, 1983.
37. U.S. Department of the Interior, Geological Survey, 7.5-Minute Series Topographic Maps,
Scale 1:24,000, Contour Interval 10 Feet: Boston North, Massachusetts, 1971.
38. U.S. Department of Interior, USGS. Topographic Maps. Scale 1:25,000, Contour Interval
10 feet. Lynn, 1970; Boston North, 1979
39. Massachusetts Metropolitan District Commission, Construction Division mapping. Town
Line Brook Topography and Linden Brook Topography. Contour Interval 2 feet, 200-foot
grid. January 1956.
40. James W. Sewall Company of Old Town, Maine. Portion of Topographic Mapping. Scale
1:4,800, contour interval 4 feet. Malden, Massachusetts. 1984.
41. Anderson-Nichols Co., Mother Brook, Flood Control Feasibility Study, Boston,
Massachusetts, February 1973.
42. U.S. Department of Housing and Urban Development, Federal Insurance Administration,
Flood Insurance Study, City of Quincy, Norfolk County, Massachusetts, Washington, D.C.,
March 1973.
43. U.S. Department of Housing and Urban Development, Federal Insurance Administration,
Flood Insurance Study, City of Newton, Middlesex County, Massachusetts, Washington,
D.C., December 1977.
44. U.S. Department of Housing and Urban Development, Federal Insurance Administration,
Flood Insurance Study, Town of Needham, Norfolk County, Massachusetts, Washington,
D.C., November 1972.
45. U.S. Department of Housing and Urban Development, Federal Insurance Administration,
Flood Insurance Study, Town of Brookline, Norfolk County, Massachusetts, Washington,
D.C., November 1976.
46. U.S. Department of Housing and Urban Development, Federal Insurance Administration,
Flood Insurance Study, Town of Winthrop, Suffolk County, Massachusetts, Washington,
D.C., September 1975.
47. U.S. Department of the Interior, Geological Survey, Water Resources Investigations 77-39,
Estimating the Magnitude and Frequency of Floods Natural-Flow Streams in
Massachusetts by S.W. Wandle, Jr., Washington, D.C. 1977.

53
48. U.S. Department of Agriculture, Soil Conservation Service, Technical Paper 149, A
Method for Estimating Volume and Rate of Runoff in Small Watersheds, Washington,
D.C., April 1973.

65
70
75 75
80 80
85 85
90 90
95 95
100 100
105 105
110 110
124400 124600 124800 125000 125200 125400 125600 125800 126000 126200 126400 126600 126800 127000
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE MOUTH
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA 
ALL JURISDICTIONS
FLOOD PROFILES
CHARLES RIVER
01P
LIMIT OF FLOODING AFFECTING COMMUNITIES
CITY OF NEWTON
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
MIDDLESEX COUNTY
SUFFOLK COUNTY
CITY OF BOSTON

65
70
75 75
80 80
85 85
90 90
95 95
100 100
105 105
110 110
127000 127200 127400 127600 127800 128000 128200 128400 128600 128800 129000 129200 129400 129600
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE MOUTH
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
CHARLES RIVER
02P
A B C
RAILROAD
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

65
70
75 75
80 80
85 85
90 90
95 95
100 100
105 105
110 110
129600 129800 130000 130200 130400 130600 130800 131000 131200 131400 131600 131800 132000 132200
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE MOUTH
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
CHARLES RIVER
03P
D
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

60
65
70 70
75 75
80 80
85 85
90 90
95 95
100 100
105 105
132200 132400 132600 132800 133000 133200 133400 133600 133800 134000 134200 134400 134600 134800
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE MOUTH
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
CHARLES RIVER
04P
E F G
SPRING STREET
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

65
70
75 75
80 80
85 85
90 90
95 95
100 100
105 105
110 110
134800 135000 135200 135400 135600 135800 136000 136200 136400 136600 136800
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE MOUTH
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
CHARLES RIVER
05P
CITY OF BOSTON
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
SUFFOLK COUNTY
NORFOLK COUNTY
TOWN OF DEDHAM
LIMIT OF FLOODING AFFECTING COMMUNITY

-15
-10
-5 -5
0 0
5 5
10 10
15 15
20 20
25 25
30 30
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CHELSEA RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MILL CREEK
06P
A B C D E
CONFLUENCE WITH CHELSEA RIVER
LIMIT OF DETAILED STUDY
BOSTON AND MAINE RAILROAD
BROADWAY
ACCESS ROAD
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
1% BACKWATER EFFECT FROM CHELSEA RIVER

20
25
30 30
35 35
40 40
45 45
50 50
55 55
60 60
65 65
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NEPONSET RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MOTHER BROOK
07P
A B C D E F
G
CONFLUENCE WITH NEPONSET RIVER
HYDE PARK AVENUE
RAILROAD
RESERVATION ROAD
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

25
30
35 35
40 40
45 45
50 50
55 55
60 60
65 65
70 70
2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NEPONSET RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MOTHER BROOK
08P
H I
J
KNIGHT STREET
RIVER STREET
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

30
35
40 40
45 45
50 50
55 55
60 60
65 65
70 70
75 75
5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH NEPONSET RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MOTHER BROOK
09P
K L
CITY OF BOSTON
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
NORFOLK COUNTY
SUFFOLK COUNTY
TOWN OF DEDHAM
LIMIT OF DETAILED STUDY

-15
-10
-5 -5
0 0
5 5
10 10
15 15
20 20
25 25
30 30
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CHARLES RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MUDDY RIVER
10P
A B C D
CONFLUENCE WITH CHARLES RIVER
STORROW MEMORIAL DRIVE
COMMONWEALTH AVENUE
SERVICE ROAD
MASSACHUSETTS TURNPIKE
RAILROAD
FENWAY
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
INTERSTATE 90
IPSWICH STREET
BEACON STREET
CULVERT

-15
-10
-5 -5
0 0
5 5
10 10
15 15
20 20
25 25
30 30
2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CHARLES RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MUDDY RIVER
11P
E
F
AGASSIZ BRIDGE
FOOTBRIDGE
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

-15
-10
-5 -5
0 0
5 5
10 10
15 15
20 20
25 25
30 30
5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CHARLES RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MUDDY RIVER
12P
G
H FOOTBRIDGE
LOUIS PASTEUR BRIDGE
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
CULVERT

-15
-10
-5 -5
0 0
5 5
10 10
15 15
20 20
25 25
30 30
7800 8000 8200 8400 8600 8800 9000 9200 9400 9600 9800 10000 10200 10400
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CHARLES RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MUDDY RIVER
13P
I
PILGRIM ROAD
BROOKLINE AVE
RIVERWAY
RIVERWAY
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
CULVERT

-15
-10
-5 -5
0 0
5 5
10 10
15 15
20 20
25 25
30 30
10400 10600 10800 11000 11200 11400 11600 11800 12000 12200 12400 12600 12800
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CHARLES RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MUDDY RIVER
14P
J
K
LONGWOOD AVENUE
NETHERLANDS ROAD
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

-15
-10
-5 -5
0 0
5 5
10 10
15 15
20 20
25 25
30 30
12800 13000 13200 13400 13600 13800 14000 14200 14400 14600 14800 15000 15200 15400
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CHARLES RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MUDDY RIVER
15P
L M N
O
BROOKLINE AVENUE
RIVER ROAD
WASHINGTON STREET
ACCESS ROAD
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
CULVERT
LEVERETT POND

-15
-10
-5 -5
0 0
5 5
10 10
15 15
20 20
25 25
30 30
15400 15600 15800 16000 16200 16400 16600 16800 17000 17200 17400 17600 17800 18000
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH CHARLES RIVER
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
MUDDY RIVER
16P
P
LIMIT OF DETAILED STUDY
WILLOW POND ROAD
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
CULVERT
LEVERETT POND WILLOW POND

-5
0
5 5
10 10
15 15
20 20
25 25
30 30
35 35
40 40
0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
17P
A B C D E F G
DAM AT LOWER MILLS
AUTHORITY RAILROAD
CENTRAL AVENUE
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
MASSACHUSETTS BAY TRANSPORTATION

-5
0
5 5
10 10
15 15
20 20
25 25
30 30
35 35
40 40
2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
18P
H I
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

0
5
10 10
15 15
20 20
25 25
30 30
35 35
40 40
45 45
5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
19P
J K L
M
TRANSPORTATION AUTHORITY
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
MASSACHUSETTS BAY

5
10
15 15
20 20
25 25
30 30
35 35
40 40
45 45
50 50
7800 8000 8200 8400 8600 8800 9000 9200 9400 9600 9800 10000 10200 10400
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
20P
N O P
Q
BLUEHILL PARKWAY
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

10
15
20 20
25 25
30 30
35 35
40 40
45 45
50 50
55 55
10400 10600 10800 11000 11200 11400 11600 11800 12000 12200 12400 12600 12800 13000
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
21P
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

10
15
20 20
25 25
30 30
35 35
40 40
45 45
50 50
55 55
13000 13200 13400 13600 13800 14000 14200 14400 14600 14800 15000 15200 15400 15600
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
22P
R S T U
RAILROAD
TILESTON AND HOLLINGSWORTH DAM
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

15
20
25 25
30 30
35 35
40 40
45 45
50 50
55 55
60 60
15600 15800 16000 16200 16400 16600 16800 17000 17200 17400 17600 17800 18000 18200
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
23P
V
RAILROAD BRIDGE
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

15
20
25 25
30 30
35 35
40 40
45 45
50 50
55 55
60 60
18200 18400 18600 18800 19000 19200 19400 19600 19800 20000 20200 20400 20600 20800
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
24P
W X Y Z
AA
CONFLUENCE OF MOTHER BROOK
FAIRMONT AVENUE
RAILROAD
DANA AVENUE
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
STRUCTURE IS NOT SHOWN
WITHIN THIS PANEL
(BOTTOM OF ROAD 53.2)

15
20
25 25
30 30
35 35
40 40
45 45
50 50
55 55
60 60
20800 21000 21200 21400 21600 21800 22000 22200 22400 22600 22800 23000 23200 23400
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
25P
AB AC
GLENWOOD AVENUE FOOTBRIDGE
RAILROAD
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

15
20
25 25
30 30
35 35
40 40
45 45
50 50
55 55
60 60
23400 23600 23800 24000 24200 24400 24600 24800 25000 25200 25400 25600 25800 26000
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
26P
AD
TRUMAN HIGHWAY
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

20
25
30 30
35 35
40 40
45 45
50 50
55 55
60 60
65 65
26000 26200 26400 26600 26800 27000 27200 27400 27600 27800 28000 28200 28400 28600
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
27P
AE
NEPONSET VALLEY PARKWAY
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

20
25
30 30
35 35
40 40
45 45
50 50
55 55
60 60
65 65
28600 28800 29000 29200 29400 29600 29800 30000 30200 30400 30600 30800 31000 31200
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE DAM AT LOWER MILLS
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNTY, MA
ALL JURISDICTIONS
FLOOD PROFILES
NEPONSET RIVER
28P
SUFFOLK COUNTY / CITY OF BOSTON
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
NORFOLK COUNTY / TOWN OF DEDHAM LIMIT OF DETAILED STUDY

35
40
45 45
50 50
55 55
60 60
65 65
70 70
75 75
80 80
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CULVERT ENTRANCE
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNT, MA
ALL JURISDICTIONS
FLOOD PROFILES
STONY BROOK
29P
ENNEKING PARKWAY
ENNEKING PARKWAY
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
CULVERT ENTRANCE LIMIT OF DETAILED STUDY

35
40
45 45
50 50
55 55
60 60
65 65
70 70
75 75
80 80
1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CULVERT ENTRANCE
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNT, MA
ALL JURISDICTIONS
FLOOD PROFILES
STONY BROOK
30P
A B C
D
ACCESS ROAD
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

70
75
80 80
85 85
90 90
95 95
100 100
105 105
110 110
115 115
2600 2700 2800 2900 3000 3100 3200 3300 3400 3500 3600 3700 3800 3900
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CULVERT ENTRANCE
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNT, MA
ALL JURISDICTIONS
FLOOD PROFILES
STONY BROOK
31P
E
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

95
100
105 105
110 110
115 115
120 120
125 125
130 130
135 135
140 140
3900 4000 4100 4200 4300 4400 4500 4600 4700 4800 4900 5000 5100 5200
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CULVERT ENTRANCE
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNT, MA
ALL JURISDICTIONS
FLOOD PROFILES
STONY BROOK
32P
F
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION

105
110
115 115
120 120
125 125
130 130
135 135
140 140
145 145
150 150
5200 5300 5400 5500 5600 5700 5800 5900 6000 6100 6200 6300 6400 6500
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CULVERT ENTRANCE
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNT, MA
ALL JURISDICTIONS
FLOOD PROFILES
STONY BROOK
33P
G H
TURTLE POND ACCESS ROAD
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
TURTLE POND

110
115
120 120
125 125
130 130
135 135
140 140
145 145
150 150
155 155
6500 6600 6700 6800 6900 7000
ELEVATION IN FEET (NAVD 88)
STREAM DISTANCE IN FEET ABOVE CULVERT ENTRANCE
FEDERAL EMERGENCY MANAGEMENT AGENCY
SUFFOLK COUNT, MA
ALL JURISDICTIONS
FLOOD PROFILES
STONY BROOK
34P
LIMIT OF DETAILED STUDY
LEGEND
0.2% ANNUAL CHANCE FLOOD
1% ANNUAL CHANCE FLOOD
2% ANNUAL CHANCE FLOOD
10% ANNUAL CHANCE FLOOD
STREAM BED
CROSS SECTION LOCATION
TURTLE POND