Prepared in cooperation with the Federal Emergency Management Agency

High-Water Marks from Tropical Storm Irene 

for Selected River Reaches in Northwestern 

Massachusetts, August 2011

Data Series 775

U.S. Department of the Interior

U.S. Geological Survey
Front cover. Photographs of Deerfield River at dam #3 at Shelburne Falls, Massachusetts. Top left photograph was taken on May 14, 2012, 

during near-normal flows. The rocky area below the dam is called the Glacial Potholes. The bottom right photograph was taken on 

August 28, 2011, during flood flows from tropical storm Irene. Photographs by John E. Robison, Amherst, Massachusetts.

Back cover. Photograph of Deerfield River at the Bridge Street bridge (left) and the Bridge of Flowers (right) at Shelburne Falls, 

Massachusetts, taken on August 28, 2011, during flood flows from tropical storm Irene. Photograph by John E. Robison, 

Amherst, Massachusetts. 
High-Water Marks from Tropical Storm 

Irene for Selected River Reaches in 

Northwestern Massachusetts, August 2011

By Gardner C. Bent, Laura Medalie, and Martha G. Nielsen

Prepared in cooperation with the Federal Emergency Management Agency

Data Series 775

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2013

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Suggested citation:

Bent, G.C., Medalie, Laura, and Nielsen, M.G., 2013, High-water marks from tropical storm Irene for selected 

river reaches in northwestern Massachusetts, August 2011: U.S. Geological Survey Data Series 775, 13 p., 

http://pubs.usgs.gov/ds/775/.
iii

Contents

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................1

Study Area..............................................................................................................................................1

Tropical Storm Irene......................................................................................................................................3

High-Water Marks .........................................................................................................................................3

Identification and Flagging..................................................................................................................9

Surveying................................................................................................................................................9

Uses of Data.........................................................................................................................................11

Summary........................................................................................................................................................11

Acknowledgments.......................................................................................................................................11

References Cited..........................................................................................................................................12

Appendix 1. Elevations of High-Water Marks Surveyed in the Deerfield and Hudson-Hoosic 

River Basins in Northwestern Massachusetts Resulting from Flooding from Tropical 

Storm Irene, August 28–29, 2011..................................................................................................13

Appendix 2. GoogleEarth Map of High-Water Marks in the Deerfield and Hudson-Hoosic 

River Basins in Northwestern Massachusetts Resulting from Flooding from Tropical 

Storm Irene, August 28–29, 2011..................................................................................................13

Figures

1. Map showing locations of U.S. Geological Survey streamgages with at least 

25 years of record in western Massachusetts ........................................................................2

2. Map showing distribution of rainfall and path of tropical storm Irene across western 

Massachusetts on August 28–29, 2011 .....................................................................................4

3. Hydrographs for U.S. Geological Survey streamgages A, Hoosic River near 

Williamstown (station 01332500) and B, Deerfield River near West Deerfield 

(station 01170000) in Massachusetts, showing a rapid rise in gage height due to 

tropical storm Irene, August 28–29, 2011..................................................................................6

4. Photographs showing examples of high-water marks associated with flooding 

from tropical storm Irene in the Deerfield and Hudson-Hoosic River Basins in northwestern Massachusetts, August 28–29, 2011: A, B, mud and debris line on buildings; 

C, debris on the ground; D, wash line on the ground; and E, debris on tree.......................7

5. Map showing locations of surveyed high-water marks from flooding due to tropical 

storm Irene in the Deerfield and Hudson-Hoosic River Basins in northwestern 

Massachusetts, August 28–29, 2011..........................................................................................8
iv

Tables

1. Peak streamflows and gage heights compared to historical peaks for U.S. 

Geological Survey streamgages in western Massachusetts, August 28–29, 2011 ...........5

2. Quantitative scale to rate accuracy of high-water marks.....................................................9

3. Quality assurance of survey equipment used by the U.S. Geological Survey to 

determine positions of high-water marks from tropical storm Irene relative to 

National Geodetic Survey benchmarks in and near the Deerfield and HudsonHoosic River Basins, western Massachusetts, June through August 2012 .....................10

Conversion Factors, Datum, and Abbreviations

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2)

Flow rate

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Elevation, as used in this report, refers to distance above the vertical datum.

Abbreviations

FEMA Federal Emergency Management Agency

GPS Global Positioning System

HWM High-water mark

NGS National Geodetic Survey

USGS U.S. Geological Survey
High-Water Marks from Tropical Storm Irene for 

Selected River Reaches in Northwestern Massachusetts, 

August 2011

By Gardner C. Bent, Laura Medalie, and Martha G. Nielsen

Abstract

A Presidential Disaster Declaration was issued for 

Massachusetts, with a focus on the northwestern counties, 

following flooding from tropical storm Irene on August 28–

29, 2011. Three to 10 inches of rain fell during the storm on 

soils that were susceptible to flash flooding because of wet 

antecedent conditions. The gage height at one U.S. Geological 

Survey (USGS) streamgage rose nearly 20 feet in less than 

4 hours because of the combination of saturated soils and 

intense rainfall. Eight of 16 USGS long-term streamgages in 

western Massachusetts set new peaks of record on August 28 

or 29, 2011. 

To document the historic water levels of the streamflows 

from tropical storm Irene, the USGS identified, flagged, and 

surveyed 323 high-water marks in the Deerfield and HudsonHoosic River basins in northwestern Massachusetts. Areas 

targeted for high-water marks were generally upstream and 

downstream from structures along selected river reaches. 

Elevations from high-water marks can be used to confirm peak 

river stages or help compute peak streamflows, to calibrate 

hydraulic models, or to update flood-inundation and recovery 

maps. For areas in western Massachusetts that flooded as a 

result of tropical storm Irene, high-water marks surveyed for 

this study have helped to confirm or determine instantaneous 

peak river gage heights at several USGS streamgages.

Introduction

The 3 to 10 inches of rainfall from tropical storm Irene 

resulted in historic rainfall and flooding on August 28–29, 

2011, in western Massachusetts. On the basis of preliminary 

damage assessments, President Obama declared a major 

disaster in the Commonwealth of Massachusetts on 

September 3, 2011, with individual and public assistance 

available for Berkshire and Franklin Counties (Federal 

Emergency Management Agency, 2013). On October 20, 

2011, the Presidential Disaster Declaration (FEMA-4028-DR) 

also designated Hampden and Hampshire Counties in 

western Massachusetts (plus five other counties in eastern 

Massachusetts) as eligible for public assistance (Federal 

Emergency Management Agency, 2013). As of February 2013, 

Federal financial assistance to Massachusetts for recovery 

from tropical storm Irene allotted more than $11 million for 

individual assistance and more than $53 million for public 

assistance (Federal Emergency Management Agency, 2013).

In response to the Presidential Disaster Declaration for 

Massachusetts resulting from tropical storm Irene (DR-4028), 

a Federal Emergency Management Agency (FEMA) Mission 

Assignment was authorized for the U.S. Geological Survey 

(USGS) to identify and flag high-water marks (HWMs) in 

northwestern Massachusetts, specifically along river reaches 

in the Deerfield and Hudson-Hoosic River Basins and to 

survey their elevations. An April 2012 Interagency Agreement 

between FEMA Region I (New England) and USGS 

authorized the surveying of HWM elevations to the North 

American Vertical Datum of 1988 (NAVD 88) for selected 

river reaches in northwestern Massachusetts as a result of 

tropical storm Irene.

Purpose and Scope

The purpose of this report is to document and provide 

data on HWMs from tropical storm Irene on August 28–29, 

2011, for selected river reaches in the Deerfield and HudsonHoosic River Basins in northwestern Massachusetts. Methods 

used to identify, flag, and survey HWMs to vertical and horizontal datums are described. This report also presents a summary of gage heights and peak streamflows, in some instances 

verified by HWMs, resulting from tropical storm Irene at 

USGS streamgages throughout western Massachusetts.

Study Area

HWMs were identified in the Deerfield and HudsonHoosic River Basins in northwestern Massachusetts (fig. 1). 

Elevations in northwestern Massachusetts range from Mount 

Greylock at 3,487 feet (ft) to the mouth of the Deerfield 

River at about 120 ft above sea level (NGVD 88). Western 
2 High-Water Marks from Tropical Storm Irene for Selected River Reaches in Northwestern Massachusetts, August 2011

EXPLANATION

Major river basin

Connecticut

Deerfield

Farmington

Housatonic

Hudson-Hoosic

Westfield

# U.S. Geological Survey 

 streamgage station and reference 

 number in table 1.

Study area

Base from U.S. Geological Survey digital data, 1:2,000,000

Geographic coordinate system North American Datum 1983

73°30' 72°45'

42°45' 

42°

Mount

Greylock

MASSACHUSETTS

NEW 

YORK

CONNECTICUT

VERMONT

NEW 

HAMPSHIRE

 Berkshire 

County

Franklin 

County 

Hampden 

County 

Hampshire 

County

9

8

7

6

5

4 3

1 2

13

12

10

16 15

14

11

# #

# #

#

#

#

#

#

# #

#

#

#

#

#

Mill River

Housatonic River

River

Deerfield 

Hoosic 

River

West Branch 

Farmington River

Westfield River

River

Connecticut 

0 10 20 KILOMETERS

0 10 20 MILES

Figure 1. Locations of U.S. Geological Survey streamgages with at least 25 years of record in western Massachusetts.
High-Water Marks 3

Massachusetts is fairly rural with most of the population living 

in the valleys of the major river basins. The Deerfield River 

has a drainage area of 665 square miles (mi2) in Vermont 

and Massachusetts (347 mi2 in Massachusetts), has multiple 

hydroelectric facilities, and is a popular fishing destination 

for native and stocked trout (Deerfield River Watershed 

Association, 2005). The Hudson-Hoosic River Basin in 

Massachusetts covers about 240 mi2 and sustains native wild 

trout (Commonwealth of Massachusetts, 2013). The largest 

tributary drainage area of the Hudson River in Massachusetts 

is that of the Hoosic River, which originates in western 

Massachusetts and flows north and west through Vermont and 

into New York State.

Tropical Storm Irene

After leaving a wake of destruction through the 

Caribbean, eastern North Carolina, and eastern New Jersey, 

Irene made landfall east of New York City as a tropical storm 

and then moved northeast over northwestern Connecticut 

and into western Massachusetts before continuing northeast 

to Vermont (Fanelli and Fanelli, 2011) (fig. 2). The highest 

observed rainfall totals from Irene in western Massachusetts 

were 9.92 inches (in.) in Conway and 9.75 in. in Ashfield 

(National Weather Service, 2011). The Northeast Regional 

Climate Center ranked August 2011, with an average rainfall 

for Massachusetts of 10.05 in., as the second wettest August 

in 117 years of precipitation records for Massachusetts; the 

wettest year was 1955 with 13.52 in. of rainfall (Northeast 

Regional Climate Center, 2011). Precipitation in western 

Massachusetts during August 2011 was 11.21 in., more than 

3 times higher than the average August precipitation (3.41 in.) 

(Massachusetts Department of Conservation and Recreation, 

2011). During August 2011 before the arrival of tropical storm 

Irene, western Massachusetts already had saturated soils from 

abundant rainfall, resulting in conditions susceptible to flash 

flooding (Northeast Regional Climate Center, 2011). 

Peak gage heights and streamflows from tropical storm 

Irene were recorded at 16 long-term (25 or more years of 

record) USGS streamgages in western Massachusetts on 

August 28 or 29, 2011 (fig. 1 and table 1). Most of the 

streamgages reached peak gage heights within about 20 hours 

of the start of the rainfall, similar to USGS 01332500 

Hoosic River near Williamstown, Mass. (fig. 3A). Some 

streamgages reached a peak gage height in about 4 hours; for 

example, the gage height at USGS 01170000 Deerfield River 

near West Deerfield, Mass. (reference number 4 on fig. 1), 

increased from about 5 ft to nearly 24 ft in less than 4 hours 

(fig. 3B). This rapid response resulted from wet antecedent 

soil conditions and very intense rainfall. Eight of 16 USGS 

streamgages in western Massachusetts with long-term records 

(ranging from 27 to 108 years) set new records for peak 

streamflows (U.S. Geological Survey, 2013) during tropical 

storm Irene (table 1). 

High-Water Marks

HWMs are the evidence of the highest water levels during a flood (Benson and Dalrymple, 1967). Bits of material, 

such as seeds, tree needles, grass, leaves, woody debris, trash, 

or sediment, that are transported by floodwaters sometimes 

remain on tree bark, buildings, or fences at the highest water 

level, leaving a trail to document the height of water (fig. 4). 

Scour lines in streambanks generally are less accurate and 

more variable than HWMs from debris or stains. The most 

useful HWMs tend to result from water that was moving at 

a low velocity with minimal wave action, usually at some 

distance from the main river channel or water body. Optimally, 

HWMs are identified immediately following peak flood levels 

because over time, rain, wind, and sun can wash, blow, or fade 

away the HWM material that depict the peak. The general 

methods used to identify and document HWMs are described 

by Benson and Dalrymple (1967).

The Deerfield and Hudson-Hoosic River Basins in northwestern Massachusetts, identified by FEMA as having more 

flood damage from tropical storm Irene than other areas of 

western Massachusetts, were the focus of this effort to document HWMs. From August 31 through September 30, 2011, 

the USGS identified and flagged 323 HWMs in those two river 

basins (fig. 5 and appendix 1). In the Deerfield River Basin, 

260 HWMs were flagged at 104 locations on 12 different 

stream reaches. In the Hudson-Hoosic River Basin, 63 HWMs 

were flagged at 30 locations on 3 different stream reaches. Of 

the 323 HWMs that were flagged, 318 were surveyed directly, 

and 5 were surveyed by an estimated method (described in the 

section “Surveying”). 
4 High-Water Marks from Tropical Storm Irene for Selected River Reaches in Northwestern Massachusetts, August 2011

Conway

Ashfield

MASSACHUSETTS

NEW YORK

VERMONT

CONNECTICUT

NEW HAMPSHIRE

73°30' 72°30'

43° 

42°30' 

42°

EXPLANATION

Precipitation amounts, in inches

> 3 to 4

> 4 to 5

> 5 to 6

> 6 to 7

> 7 to 8

> 8 to 9

> 9 to 11

> 11 to 13

Study Area

Path of tropical storm Irene

Precipitation data points

0 10 20 40 MILES

0 20 40 KILOMETERS

Base from U.S. Geological Survey Data, 1:2,000,000 digital line graphs,

Geographic coordinate system North American Datum 1983

Figure 2. Distribution of rainfall and path of tropical storm Irene across western Massachusetts on August 28–29, 2011. 

Information on the precipitation data points and the path of tropical storm Irene is from the National Oceanic and Atmospheric 

Administration (2011a and b). (>, greater than)
High-Water Marks 

5

Table 1. Peak streamflows and gage heights compared to historical peaks for U.S. Geological Survey streamgages in western Massachusetts, August 28–29, 2011.[Source of peak streamflow data is U.S. Geological Survey (USGS), 2013; mi2, square miles; ft, feet; ft3/s, cubic feet per second; --, data are not available]

Reference 

number 

for 

figure 1

USGS 

station 

number

USGS station name

Drainage 

area 

(mi2)

August 2011 peak streamflow 

(bold indicates new peak of record) Historical peak streamflow

Date

Gage 

height 

(ft)

Streamflow 

(ft3/s)

Time to 

peak from 

base flow 

(hours)

Date

Gage 

height 

(ft)

Streamflow 

(ft3/s)

Number of 

years of 

record

Deerfield River Basin

1 01168500 Deerfield River at Charlemont, Mass. 361 8/28/2011 20.17a 54,000 -- 9/21/1938 20.17 56,300 982 01169000 North River at Shattuckville, Mass. 89 8/28/2011 17.99 56,100 12 10/9/2005 12.32 18,800 723 01169900 South River near Conway, Mass. 24 8/28/2011 14.27 13,000 15 10/9/2005 11.90 8,770 454 01170000 Deerfield River near West Deerfield, Mass. 557 8/28/2011 23.77 103,000 18 4/5/1987 17.71 61,700 715 01170100 Green River near Colrain, Mass. 41 8/28/2011 13.98 19,400 9 10/9/2005 9.14 6,540 44

Connecticut River Basin

6 01170500 Connecticut River at Montague City, Mass. 7,860 8/28/2011 35.91 127,000 16 3/19/1936 49.20 236,000 1087 01171500 Mill River at Northampton, Mass. 53 8/28/2011 16.42b 7,020 13 8/19/1955 11.78 6,300 73

Westfield River Basin

8 01181000 West Branch Westfield River at Huntington, Mass. 94 8/28/2011 16.78 32,400 -- 8/19/1955 15.27 26,100 769 01183500 Westfield River near Westfield, Mass. 497 8/28/2011 19.92 26,200 15 8/19/1955 34.20 70,300 97

Farmington River Basin

10 01185500 West Branch Farmington River near New Boston, Mass. 92 8/28/2011 11.50 17,300 12 8/19/1955 14.06 34,300 98

Housatonic River Basin

11 01197000 East Branch Housatonic River at Coltsville, Mass. 58 8/28/2011 8.20c 6,410 19 9/21/1938 10.80 6,400 76

12 01197500 Housatonic River near Great Barrington, Mass. 282 8/29/2011 9.62d 6,780d 29 1/1/1949 12.08 12,200 9813 01198000 Green River near Great Barrington, Mass. 51 8/28/2011 12.46 7,550 17 7/13/1996 9.84 6,740 27e

Hudson-Hoosic River Basin

14 01331500 Hoosic River at Adams, Mass. 47 8/28/2011 9.50b 2,690 15 9/21/1938 8.25 5,080 8015 01332500 Hoosic River near Williamstown, Mass. 126 8/28/2011 14.58 14,900 14 12/31/1948 14.85 13,000 7116 01333000 Green River at Williamstown, Mass. 43 8/28/2011 6.67 4,140 -- 12/21/1973 5.68 4,060 62

aThe rating curve (relation between gage height and streamflow) has changed between 1938 and 2011; thus, the same gage height (20.17 ft) for the peaks in 2011 and 1938 produces different streamflows.bGage height is higher than the historical peak gage height due to a change in the gage datum.cGage height is lower than the historical peak gage height due to a change in the gage datum.dPeak streamflow of water year 2011 occurred on a different date.eRecord of streamflow is not continuous.
6 High-Water Marks from Tropical Storm Irene for Selected River Reaches in Northwestern Massachusetts, August 2011

Missing data

A

B

Figure 3. Hydrographs for U.S. Geological Survey streamgages A, Hoosic River near Williamstown (station 01332500) 

and B, Deerfield River near West Deerfield (station 01170000) in Massachusetts, showing a rapid rise in gage height 

due to tropical storm Irene, August 28–29, 2011. About 14 hours of data are missing in the station 01170000 hydrograph 

due to equipment malfunction.
High-Water Marks 7

A. HWM-MA-EBNORTH-160 C. HWM-MA-HOOSIC-276

E. HWM-MA-EBNORTH-157

D. HWM-MA-CHICKLEY-225

B. HWM-MA-GREEN-079

Figure 4. Examples of high-water marks associated with flooding from tropical storm Irene in the Deerfield and Hudson-Hoosic River 

Basins in northwestern Massachusetts, August 28–29, 2011: A, B, mud and debris line on buildings; C, debris on the ground; D, wash line 

on the ground; and E, debris on tree.
8 High-Water Marks from Tropical Storm Irene for Selected River Reaches in Northwestern Massachusetts, August 2011 Base from U.S. Geological Survey digital data, 1:24,000 Geographic coordinate system North American Datum 1983 MILES

0 5 100 5 10

KILOMETERS

Deerfield R. 

Connecticut R. 

Green R. 

South R. 

Hoosic 

North Branch 

Cold R. 

Chickley R. 

Pelham Brook 

Mill B ook r

North R. 

Clesson B

W

ook r

est Branch North R. 

East Branch North R. 

Hoosic R. 

R. 

Hoosic R.

Deerfield R. 

MASSA

CHUSETT

S

VERMON

T

MountGreylock

72°40' 73°0'

42°45' 42°30' 

EXPLAN

ATION

River basin

DeerfieldHudson-Hoosic 

Surveyed high-water marks

Figure 5. Locations of surveyed high-water marks from flooding due to tropical storm Irene in the Deerfield and Hudson-Hoosic River Basins in northwestern Massachusetts, August 28–29, 2011.
High-Water Marks 9

Identification and Flagging

USGS field personnel working in pairs identified and 

flagged HWMs at locations upstream and downstream from 

structures along the largest stream reaches within the 

Deerfield and Hudson-Hoosic River Basins. Targeted structures included bridges for State, city, or town roads, trains, 

driveways, or pedestrians; dams; wastewater-treatment and 

other infrastructure facilities; and USGS streamgages. At each 

structure, attempts were made to find at least one upstream and 

one downstream HWM whose quality could be characterized 

as “good” or “excellent” according to a quantitative accuracy 

scale (table 2; modified from Lumia and others, 1987). For 

each HWM, a durable identification mark was made using 

a USGS HWM disk, stake, chisel mark, or permanent pen 

(fig. 4). Survey flagging was placed at each HWM location 

to facilitate the ability of survey crews to find the location 

at a later date. Information recorded on field forms for each 

HWM included a physical description of the HWM, horizontal 

location by latitude and longitude using measurements from a 

handheld Global Positioning System (GPS), rating of general 

accuracy (Lumia and others, 1987), description of the durable 

identification mark left by the USGS crew, and directions for 

survey crews to find the HWM. Photographs of the HWMs 

and the surrounding area were taken as part of the documentation1

 and to help future survey crews find the marks.

Surveying

Elevations of most of the HWMs that had been 

identified and flagged during August and September 2011 

were surveyed from June through August 2012 to NAVD 

88 using the Global Navigation Satellite System, survey 

grade GPS receivers, and total station surveying equipment. 

Surveying methods followed those described by Rydlund 

and Densmore (2012). Eleven of the HWMs flagged during 

August and September 2011 were surveyed during April and 

May 2013. Five of the original 323 HWMs could not be found 

(HWM-MA-CLESSON-202, HWM-MA-DEERFIELD-031, 

HWM-MA-GREEN-092, HWM-MA-GREEN-093, and 

HWM-MA-WBNORTH-175 in appendix 1) because either the 

HWM had been removed or the elevation had clearly changed. 

The elevations for these five HWMs were estimated by 

surveying at the ground elevation that was described when the 

site was flagged in August and September 2011 and adding the 

distance from the ground to the HWM, as measured by tape 

and recorded in the field notes. GPS surveys were conducted 

using Trimble® R8 GPS system receivers. If the HWM itself 

could not be physically accessed for the survey, other options 

1

Photographs of the HWMs are available by contacting the Chief of the 

Massachusetts-Rhode Island Office of the New England Water Science Center, 

dc_ma@usgs.gov.

Table 2. Quantitative scale to rate accuracy of high-water 

marks (modified from Lumia and others, 1987).

[±, plus or minus; >, greater than]

Rating Accuracy, 

in feet

Excellent ±0.02

Good ±0.05

Fair ±0.10

Poor ±0.20

Very poor > ±0.20

were to (1) survey a point directly above or below the HWM 

and measure the elevation difference to the HWM with a tape 

measure or (2) survey a surrogate point nearby and use a total 

station to measure the elevation difference. The GPS receiver 

was reinitialized (flipped upside down for several seconds 

or rotated 180 degrees to lose the GPS signals) several times 

at each point to obtain multiple independent readings. If the 

vertical elevations of the multiple readings differed by more 

than about 0.10 ft, additional readings were taken until the 

differences were less than 0.10 ft. In most cases, agreement 

within 0.05 ft was reached.

Continuous real-time differential corrections to the 

GPS horizontal and vertical positions were made using a 

proprietary fixed-base station GPS network of receivers 

operated by KeyNetGPS, Inc. (2013). The fixed-base station 

GPS network of receivers and associated software determined 

corrections for satellite signals received by the field GPS 

receiver for ionosphere and other atmospheric disturbances. 

The fixed-base station GPS network of receivers continuously 

streamed data to a central server that calculated corrections in 

real time to the field GPS receiver. The five fixed-base station 

GPS receivers closest to the western Massachusetts survey 

area (HAMP in western Massachusetts, NYAB and NYHS in 

eastern New York, and VTBE and VTD2 in southern Vermont) 

composed the network that was utilized for these corrections 

(KeyNetGPS, Inc., 2013).

Checks on the accuracy of the GPS measurements were 

made by comparing instrument readings from two types of 

survey equipment at 10 National Geodetic Survey (NGS) 

benchmarks with vertical datums throughout the study area 

between June and August 2012 (table 3). Differences in elevations between NGS benchmarks and those determined using 

survey equipment at the benchmarks yielded a vertical root 

mean square error of 0.15 ft. 
10 High-Water Marks from Tropical Storm Irene for Selected River Reaches in Northwestern Massachusetts, August 2011

Table 3. Quality assurance of survey equipment used by the U.S. Geological Survey to determine positions of high-water marks 

from tropical storm Irene relative to National Geodetic Survey benchmarks in and near the Deerfield and Hudson-Hoosic River 

Basins, western Massachusetts, June through August 2012.

[NAD 83, North American Datum of 1983; NAVD 88, North American Vertical Datum of 1988; NGS, National Geodetic Survey; ft, feet; WGS 84, World 

Geodetic System of 1984]

Date

Benchmark

County

Surveyed, 

in NAD 831 NGS reference, 

NAVD 88 

elevation, 

adjusted

(ft)

Elevation 

difference 

between NGS 

and surveyed 

values

(ft)

Designation 

(stamped 

name)

Permanent 

identifier

Latitude 

(north)

Longitude 

(west) NAVD 88 

elevation

(ft) Decimal 

degrees

Decimal 

degrees

Trimble TSC2® Survey Unit

6/5/2012 P9 MZ0415 BERKSHIRE 42.632368 73.113672 759.88 760.02 0.14

6/7/2012 L9 MZ0409 BERKSHIRE 42.553868 73.165154 974.58 974.67 0.09

6/12/2012 E11 MZ0280 FRANKLIN 42.616148 72.743125 506.44 506.36 -0.08

6/14/2012 X40 MZ1181 FRANKLIN 42.580416 72.599227 144.21 144.19 -0.02

6/19/2012 S5 MZ0232 FRANKLIN 42.568834 72.591037 188.66 188.66 0.00

6/21/2012 X40 MZ1181 FRANKLIN 42.580416 72.599227 144.10 144.19 0.09

8/2/2012 X40 MZ1181 FRANKLIN 42.580416 72.599227 144.39 144.19 -0.20

8/10/2012 S5 MZ0232 FRANKLIN 42.568834 72.591037 188.68 188.66 -0.02

8/21/2012 S5 MZ0232 FRANKLIN 42.568834 72.591037 188.59 188.66 0.07

8/23/2012 D33 NEPA MZ0286 FRANKLIN 42.560074 72.678673 240.19 240.29 0.10

Trimble TSC3® Survey Unit

6/6/2012 N11 MZ0369 BERKSHIRE 42.738259 73.210933 593.49 593.57 0.08

6/13/2012 X40 MZ1181 FRANKLIN 42.580416 72.599227 144.17 144.19 0.02

6/15/2012 Y9 MZ0287 FRANKLIN 42.561383 72.679986 240.34 240.42 0.08

6/21/2012 D33 NEPA MZ0286 FRANKLIN 42.560075 72.678673 240.49 240.29 -0.20

6/26/2012 X40 MZ1181 FRANKLIN 42.580416 72.599227 144.14 144.19 0.05

7/12/2012 J33 MZ0266 FRANKLIN 42.642113 72.923880 601.82 602.19 0.37

7/12/2012 F11 MZ0265 FRANKLIN 42.642158 72.924815 603.21 603.30 0.09

7/17/2012 E11 MZ0280 FRANKLIN 42.616147 72.743124 506.62 506.36 -0.26

7/19/2012 E11 MZ0280 FRANKLIN 42.616148 72.743125 506.65 506.36 -0.29

8/15/2012 X40 MZ1181 FRANKLIN 42.580416 72.599227 144.01 144.19 0.18

8/21/2012 S5 MZ0232 FRANKLIN 42.568834 72.591037 188.72 188.66 -0.06

1

Units of the original horizontal survey were in WGS 84; transformation to NAD 83 results in negligible differences.
Acknowledgments 11

Uses of Data

HWM elevations are used in hydrologic studies in 

several ways: to confirm peak river stages, to help compute 

peak streamflows, to calibrate hydraulic models, and to 

update flood inundation and flood insurance rate maps. In 

western Massachusetts, HWMs from tropical storm Irene 

have been used to determine or confirm instantaneous peak 

river gage heights at 10 USGS streamgages, 2 of which were 

up to 20 miles outside the study area. For example, at USGS 

streamgage Deerfield River at Charlemont (01168500), flood 

streamflows overtopped the instrument shelter, and HWMs 

were used to determine the peak river gage height that would 

otherwise have been lost. At USGS streamgages North River 

at Shattuckville (01169000), South River near Conway 

(01169900), Green River near Colrain (01170100), West 

Branch Westfield River at Huntington (01181000, outside the 

study area), and Green River at Williamstown (01333000), 

the HWMs were used to adjust the streamgages recorded peak 

gage heights to higher values; this was needed to fix values 

that were incorrectly recorded too low as a result of drawdown 

or intakes with slow response times. At USGS streamgages 

Deerfield River near West Deerfield (01170000), Mill River at 

Northampton (01171500, outside the study area), Hoosic River 

at Adams (01331500), and Hoosic River near Williamstown 

(01332500), HWMs were used to confirm peak river stages 

that were either recorded electronically or observed from a 

crest-stage gage. 

Summary

On August 28–29, 2011, intense rainfall from tropical 

storm Irene of 3 to 10 inches caused widespread flooding 

in western Massachusetts. August precipitation in western 

Massachusetts prior to tropical storm Irene had already 

saturated the ground resulting in conditions prone to flooding. 

Eight of 16 long-term U.S. Geological Survey (USGS) 

streamgages in western Massachusetts that had been in 

operation for more than 25 years recorded new streamflow 

peaks from tropical storm Irene. In order to document the peak 

river stage elevations from tropical storm Irene in western 

Massachusetts, the Federal Emergency Management Agency 

authorized a Mission Assignment for the USGS to identify and 

flag high-water marks (HWMs) along affected river reaches in 

the Deerfield and Hudson-Hoosic River Basins and to survey 

their elevations.

From August 31 through September 30, 2011, the U.S. 

Geological Survey identified and flagged 323 HWMs: 260 

in the Deerfield River Basin at 104 locations on 12 different 

stream reaches and 63 in the Hudson-Hoosic River Basin at 

30 locations on 3 different stream reaches. The HWMs were 

typically identified upstream and downstream from structures 

(bridges, dams, and wastewater-treatment facilities, or USGS 

streamgages) on the selected river reaches. At each flagged 

HWM, information including the physical description of the 

HWM, horizontal location (latitude and longitude), rating of 

accuracy, description of the durable marker left by the USGS 

crew, and directions for finding the HWM at a later date by 

survey crews, was recorded on field forms. In addition, photographs of the HWM and surrounding area were taken. 

Elevations of HWMs were surveyed from June through 

August 2012, and April and May 2013 vertically to the North 

American Vertical Datum of 1988 (NAVD 88) and horizontally to the North American Datum of 1983 (NAD 83) using 

the Global Navigation Satellite System, survey grade Global 

Positioning System (GPS) receivers, and total station surveying equipment. Continuous real-time differential corrections 

to the GPS positions were made using a proprietary fixedbase station GPS network of receivers. Quality-assurance 

GPS measurements made at 10 established National Geodetic 

Survey benchmarks with a vertical datum throughout the study 

area yielded a vertical root mean square error of 0.15 feet. 

Five of the original 323 HWM elevations that could not be 

found were surveyed at estimated points. 

Acknowledgments

The authors thank the following U.S. Geological Survey 

(USGS) field personnel for identifying and flagging highwater marks during September 2011: Christopher Bruet, Paul 

Friesz, Pam Lombard, Steven O’Brien, John O’Byran, Gene 

Parker, David Thompson, and Andrew Waite. The authors 

thank the following USGS field personnel for surveying highwater marks from June through August 2012, and April and 

May 2013: Roy Apostle, David Armstrong, Dennis Claffey, 

Adam Hudziec, Andrew Massey, and William Podolski. The 

authors also thank the many landowners who allowed access 

to their property to identity, flag, and survey high-water marks.
12 High-Water Marks from Tropical Storm Irene for Selected River Reaches in Northwestern Massachusetts, August 2011

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Appendixes 13

Appendix 1. Elevations of High-Water Marks Surveyed 

in the Deerfield and Hudson-Hoosic River Basins in 

Northwestern Massachusetts Resulting from Flooding from 

Tropical Storm Irene, August 28–29, 2011

[Available separately at http://pubs.usgs.gov/ds/775/]

Appendix 2. GoogleEarth Map of High-Water Marks in the 

Deerfield and Hudson-Hoosic River Basins in Northwestern 

Massachusetts Resulting from Flooding from Tropical Storm 

Irene, August 28–29, 2011

[Available separately at http://pubs.usgs.gov/ds/775/]
Prepared by the Pembroke and West Trenton Publishing 

Service Centers.

For more information concerning this report, contact:

Office Chief

U.S. Geological Survey

New England Water Science Center 

Massachusetts-Rhode Island Office

10 Bearfoot Road

Northborough, MA 01532

dc_ma@usgs.gov

or visit our Web site at:

http://ma.water.usgs.gov
Printed on recycled paper

Bent and others—High-Water Marks from Tropical Storm Irene for Selected River Reaches in Northwestern Massachusetts, August 2011—Data Series 775