Prepared in cooperation with the Federal Emergency Management Agency

High-Water Marks From Flooding in Lake Champlain 

from April through June 2011 and Tropical Storm Irene 

in August 2011 in Vermont

Data Series 763

U.S. Department of the Interior

U.S. Geological Survey
Cover. Covered bridge over Otter Creek showing a high-water mark (silt line) from tropical storm Irene, August 29. 2011.
High-Water Marks From Flooding 

in Lake Champlain from April through 

June 2011 and Tropical Storm Irene 

in August 2011 in Vermont

By Laura Medalie and S.A. Olson

Prepared in cooperation with the Federal Emergency Management Agency

Data Series 763

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:

Medalie, Laura, and Olson, S.A., 2013, High-water marks from flooding in Lake Champlain from April through June 

2011 and Tropical Storm Irene in August 2011 in Vermont: U.S. Geological Survey Data Series 763, 11 p., available at 

http://pubs.usgs.gov/ds/763/
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................2

Study Area..............................................................................................................................................2

Lake Champlain Flooding from April through June 2011 ...............................................................2

Tropical Storm Irene.............................................................................................................................4

Methods...........................................................................................................................................................8

Flagging and Documenting High-Water Marks ...............................................................................8

Surveying High-Water Marks .............................................................................................................8

Summary..........................................................................................................................................................8

References Cited..........................................................................................................................................10

Appendix 1. Report prepared by Dewberry to document the Vermont high-water mark survey, 

September 19, 2012. .......................................................................................................................11

Appendix 2. Elevations of high-water marks from flooding in Lake Champlain from April 

through June 2011 and tropical storm Irene, August 28–29, 2011, in Vermont. ...................11

Appendix 3. Map of high-water marks from flooding in Lake Champlain from April through 

June 2011 and tropical storm Irene, August 28–29, 2011, in Vermont. ..................................11

Figures

1. Map showing locations of surveyed high-water marks from flooding in Lake 

Champlain from April through June and from tropical storm Irene in August 2011 

in Vermont. .....................................................................................................................................3

2. Graph showing the gage height at the U.S. Geological Survey Lake Champlain at 

Burlington, Vermont, gaging station (04294500) from April 1 through June 20, 2011.........4

3. Map showing rainfall totals and path of tropical storm Irene, August 28–29, 2011, 

in Vermont. .....................................................................................................................................6

4. Photographs of high-water marks associated with flooding from tropical storm 

Irene in August 2011 in Vermont. These photographs represent typical manifestations 

of high-water marks and are ordered generally from best to poorest quality: A, mud 

line on a building; B, debris line on a fence; C, silt line on a tree; and D, wash line on 

the ground......................................................................................................................................9

Tables

1. Damages and responses to the floods in Vermont in 2011: in Lake Champlain 

April through June and statewide due to tropical storm Irene in August...........................2

2. Peak streamflows and stages compared to historical peaks for U.S. Geological 

Survey gaging stations with stages above National Weather Service flood stage 

in Vermont from April 1 through June 30, 2011 ........................................................................5

3. Peak streamflows and stages compared to historical peaks for U.S. Geological 

Survey gaging stations in and near Vermont, August 27–31, 2011.......................................7

4. Quantitative scale to rate accuracy of high-water marks....................................................8
iv

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

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, unless otherwise noted, 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) 

and to the Vermont State Plane Coordinate System.

Abbreviations

FEMA Federal Emergency Management Agency

GPS Global Positioning System

HWM high-water mark

NAD 83 North American Datum of 1983

NAVD 88 North American Vertical Datum of 1988

PDA personal digital assistant

USGS U.S. Geological Survey
High-Water Marks from Flooding in Lake Champlain 

from April through June 2011 and Tropical Storm Irene 

in August 2011 in Vermont

By Laura Medalie and S.A. Olson

Abstract

The U.S. Geological Survey, in cooperation with the Federal Emergency Management Agency, identified high-water 

marks after two floods in Vermont during 2011. Following a 

snowy winter, new monthly precipitation records were set in 

Burlington, Vermont, in April and May 2011, causing extensive flooding from April through June. The spring 2011 flooding resulted in a new record for stage (103.27 feet, referenced 

to the National Geodetic Vertical Datum of 1929) at the Lake 

Champlain at Burlington, Vt., gaging station (04294500). 

During August 28 and 29, 2011, tropical storm Irene delivered 

rainfall totals of 3 to more than 7 inches throughout Vermont, 

which resulted in extensive flooding and new streamflow 

records at nine streamgaging stations. Four presidential declarations of disaster were made following the 2011 flood events 

in Vermont.

Thirty-nine high-water marks were identified and flagged 

to mark the highest levels of Lake Champlain from the May 

2011 flooding, and 1,138 high-water marks were identified 

and flagged along Vermont rivers after flooding from tropical 

storm Irene in August 2011. Seventy-four percent of the highwater marks that were flagged were later found and surveyed 

to the North American Vertical Datum of 1988.

Introduction

A snowy winter capped by a snow storm that set a record 

for the greatest total snowfall of any March storm (in Burlington, Vermont), followed by monthly precipitation records 

set in April and May 2011 (also in Burlington) caused historic flooding to Lake Champlain. Just three months later, in 

August, more record-breaking rainfall and damaging winds 

from hurricane Irene (downgraded to a tropical storm before 

entering New England) resulted in extensive destruction and 

millions of dollars of damages in the eastern United States. 

During the spring event, nine streamgages on five rivers 

plus two Lake Champlain gaging stations were at or above 

National Weather Service flood stage for as much as 68 days. 

During tropical storm Irene, eight streamgages in Vermont 

measured new streamflow peaks of record, which equaled or 

exceeded the 1-percent annual exceedance probability1

 for 

events (U.S. Geological Survey, 2011). 

Presidential declarations of major disasters were made in 

June, July, and November 2011 (Federal Emergency Management Agency (FEMA) directives FEMA–1995–DR, FEMA–

4001–DR, and FEMA–4043–DR) under the Robert T. Stafford 

Disaster Relief and Emergency Assistance Act (Stafford act)2

in response to the severe storms and flooding during April and 

May 2011. Responding to the spring flooding, declarations 

were requested by Governor Peter Shumlin for individual 

assistance for 10 counties, public assistance for 11 counties, 

and hazard mitigation statewide. 

Following tropical storm Irene, the President declared 

major disaster FEMA–4022–DR for the State of Vermont 

on September 1, 2011. This declaration and its subsequent 

amendments authorized individual assistance for 12 counties, public assistance for all 14 counties, and hazard mitigation statewide. Table 1 provides a partial list of damages and 

responses to the two events.

High-water marks (HWMs) from major storm events provide evidence of the highest water-surface elevations reached 

by a flood. This information is necessary for documenting the 

magnitude and extent of flooding to support State and local 

governments and FEMA in making eligibility determinations 

under the Public Assistance and Individual Assistance Grant 

Programs. Data from HWMs also are used to determine appropriate hazard mitigation measures to minimize flood losses 

in future disasters, to prioritize and allocate disaster funding, 

and to support recovery activities authorized by the Stafford 

act. To support flood recovery efforts from the two major 

flood events in 2011 and carry out the Hazard Mitigation 

1

The 1-percent annual exceedance probability has a 1 in 100 chance of 

being equaled or exceeded in any 1 year and has an average recurrence interval of 100 years. It is often referred to as the “100-year flood.”

2

Robert T. Stafford Disaster Relief and Emergency Assistance Act, Public 

Law 93–288 (1974; codified as amended at 42 U.S.C. §§ 5121–5207). 
2 High-water marks from flooding in Lake Champlain, April–June 2011, and Tropical Storm Irene, August 2011, in Vermont

Table 1. Damages and responses to the floods in Vermont in 2011: in Lake Champlain April through June and statewide due to tropical 

storm Irene in August.

[Data are from Lake Champlain Basin Program (2012). FEMA, Federal Emergency Management Agency; VTrans, Vermont Agency of Transportation)]

April through June 2011 Lake Champlain flood Tropical storm Irene

Damages

419 homes damaged and 24 destroyed in Vermont Damage includes 30,000 homes, 500 mobile homes, 600 historic 

buildings, 500 miles of state roads, 200 miles of railroads, 1,000 

culverts, 200 bridges

All-time high phosphorus loading to Lake Champlain 34 bridges closed

Vermont State Government shut down and flooded out of the Waterbury complex1

Responses

In Vermont, FEMA awarded $1.8 million in individual assistance 

and $8.6 million in public assistance

More than 7,000 individuals registered for FEMA assistance

Road crews worked overtime to repair and establish alternative 

routes (hundreds of detours)

Volunteer and community response

VTrans asked other agencies and commissions to work with towns 

so that VTrans could focus exclusively on state transportation 

infrastructure

Established detours and restored access to communities

Assistance from National Guard (7 states) and workers and vehicles 

from the Maine and New Hampshire Departments of Transportation 

1

Approximately 1,500 employees were displaced from the Waterbury complex.

Grant Program for the State of Vermont, the U.S. Geological 

Survey (USGS), in cooperation with FEMA under Mission 

Assignment 4022–DR–VT–USGS–01, identified HWMs in 

Vermont between August and October 2011 and arranged 

a contract with a consultant to obtain surveyed elevations 

for those HWMs (appendix 1; Dewberry, written commun., 

2012). Surveyed elevations for HWMs will be used by USGS 

to generate flood inundation maps for selected study reaches 

along major flooding sources in Vermont that experienced less 

than 1-percent annual exceedance probability streamflows and 

significant damages.

Purpose and Scope

The objective of this study is to provide a quantitative 

record of the spring 2011 flooding of Lake Champlain in Vermont and the tropical storm Irene flood event in Vermont that 

will assist in implementing relief from the Stafford act for the 

major disaster declarations from these events. The cooperative 

agreement between FEMA and USGS consists of four major 

tasks related to this objective—the first of which is the subject 

of this report: locating HWMs from the flood events and surveying them into a known base datum to document the extent 

and the depth of flooding. 

Study Area

HWMs from the April through June 2011 Lake Champlain flooding were identified and flagged in four Vermont 

counties (Addison, Chittenden, Franklin, and Grand Isle) during August 2011 (fig. 1). HWMs from flooding due to tropical 

storm Irene were flagged in all Vermont counties except Essex 

and Lamoille during September and October 2011, with the 

greatest numbers in Windsor and Windham Counties (fig. 1).

Lake Champlain Flooding from April through 

June 2011 

Extensive flooding around Lake Champlain and northern Vermont occurred from April through June 2011. Lake 

Champlain levels were above the National Weather Service 

(NWS) flood stage of 100 feet3 for 68 days between April 13 

3

 Stages of Lake Champlain in this discussion of flooding are referenced 

to the National Geodetic Vertical Datum of 1929 (NGVD 29). Elevations of 

HWMs surveyed for this project are referenced to the North American Vertical 

Datum of 1988 (NAVD 88). At the USGS Lake Champlain at Burlington gaging station (04294500), elevations presented in NGVD 29 are 0.48 ft greater 

than elevations in NAVD 88.
Introduction 3

.

CHITTENDEN

LAMOILLE

CALEDONIA

WASHINGTON

ADDISON ORANGE

ORLEANS

GRAND ISLE FRANKLIN

ESSEX

RUTLAND

WINDSOR

WINDHAM

BENNINGTON

Otter Creek

Mad River

Winooski River

Lamoille River

Missisquoi River

C

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c t i c

u t R i v

e

r

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e

c t i c

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t

R i v

e

r

Lake Champlain

0

0 KILOMETERS

MILES

10 20

10 20

(BoundaryOther_BNDHASH), 1:24,000, 2012.

Base from Vermont Center for Geographic Information, boundary data layer

73 ° 72 °

45 °

44 °

43 °

Montpelier

Barre City

Burlington

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8 7

6 5

4

3 2

1

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#

12

21

20

14

19

15

10

18

16

17

11

13

High-water marks from:

EXPLANATION

County boundary

Lake Champlain flood

U.S. Geological Survey

gaging station and reference

number in tables 2 and 3

Tropical storm Irene

Figure 1. Locations of surveyed high-water marks from flooding in Lake Champlain from April through June and from 

tropical storm Irene in August 2011 in Vermont.
4 High-water marks from flooding in Lake Champlain, April–June 2011, and Tropical Storm Irene, August 2011, in Vermont

and June 18 (fig. 2) and were above the previous maximum 

observed elevation of 101.86 feet (observed on April 27, 1993) 

for 39 of those days. The stage was set for spring flooding as 

the third snowiest winter on record in Burlington was capped 

on March 6–7, 2011, with the third largest snowfall ever 

recorded in Burlington and greatest total of any March storm 

measured at the NWS Burlington International Airport station 

(Vermont State Climate Office, 2011a). Precipitation records 

continued to be set in Burlington (Vermont State Climate 

Office, 2011b) in April (7.88 inches) and May (8.67 inches); 

all together, the wettest spring on record was observed in 

Burlington (19.94 inches for March through May 2011). A 

new record for stage, 103.27 feet (ft), was recorded on May 

6 at the USGS Lake Champlain at Burlington gaging station (04294500; fig. 2). At its greatest inundation on May 6, 

2011, when stage was 103.27 ft (compared to a baseline stage 

of 94.5 ft), the surface area of Lake Champlain increased by 

approximately 15 percent (66 square miles) and the volume 

of the water in the lake increased by 12.7 percent (867 billion 

gallons) (Lake Champlain Basin Program, 2011).

Also during this flood event, snowmelt compounded by 

extensive thunderstorm rainfall resulted in record stage levels 

and streamflows in several tributaries in the Lake Champlain 

basin and subsequent localized flooding. Barre City and Montpelier in central Vermont, in particular, suffered significant 

damage by flooding (WCAX–TV, 2011)—about 200 people in 

the area were sent to emergency shelters. Otter Creek and the 

Winooski, Mad, Lamoille, and Missisquoi Rivers were above 

flood stage for 1 to 8 days during April or May 2011 (table 2; 

U.S. Geological Survey, 2012). 

Tropical Storm Irene

Just 3 months after the historic springtime flooding on 

Lake Champlain, tropical storm Irene moved through Vermont, resulting in a second presidential declaration of disaster in 2011 for Vermont, this time for the entire State. From 

August 28 through 29, 2011, rainfall from Irene totaled from 3 

to more than 7 inches throughout Vermont (National Weather 

Figure 2. Gage height at the U.S. Geological Survey Lake Champlain at Burlington, Vermont, gaging 

station (04294500) from April 1 through June 20, 2011.
Introduction 

5

Table 2. Peak streamflows and stages compared to historical peaks for U.S. Geological Survey gaging stations with stages above National Weather Service flood stage in Vermont from April 1 through June 30, 2011.[ft, feet; ft3/s, cubic feet per second; mi2, square miles; NWS, National Weather Service; USGS, U.S. Geological Survey; --, no data]

Reference 

number, as 

shown on 

figure 1

USGS 

gaging station 

number

USGS gaging station name

Drainage 

area, 

in mi2

NWS 

flood 

stage, 

in ft

Number of 

days above 

NWS flood 

stage

Highest peak, from April 1 

through June 30, 2011 Historical peak

Date Stage, in ft Stream discharge, in ft3/s Maximum stream discharge, in ft3/s Year Number of years of record

1 04282000 Otter Creek at Center Rutland 307 8 5 4/13 9.35 4,880 15,700 2011 833 04288000 Mad River near Moretown 139 9 2 4/12 9.14 6,390 24,200 2011 844 04290500 Winooski River near Essex Junction 1,044 12 8 4/12 17.24 28,100 113,000 1927 845 04292000 Lamoille River at Johnson 310 13 3 4/27 16.97 13,800 19,000 1995 856 04292201 Lamoille River at Jeffersonville 489 450 6 4/27 454.21 24,600 -- -- --7 04293000 Missisquoi River near North Troy 131 9 3 4/27 12.95 9,540 11,500 2002 808 04293500 Missisquoi River near East Berkshire 479 13 4 4/28 13.99 14,500 45,000 1927 959 04294500 Lake Champlain at Burlington -- 100 68 5/06 103.27 -- -- -- --
6 High-water marks from flooding in Lake Champlain, April–June 2011, and Tropical Storm Irene, August 2011, in Vermont

Service, 2011); heaviest amounts generally occurred along 

the storm track in the eastern axis of the State (fig. 3). New 

record streamflows were recorded at nine sites in or bordering 

Vermont and nine other sites had peak streamflows among the 

top four of record (table 3; U.S. Geological Survey, 2011). 

The magnitude of the flood, which affected 225 (88 percent) 

of municipalities in the State, approached that of the historic 

1927 flood. Damage to the transportation sector included 

more than 500 miles of road and about 200 bridges of the 

State highway system; more than 2,000 road segments, more 

than 280 bridges, and about 960 culverts of the municipal 

road system; and more than 200 miles of railroad and 6 

railroad bridges of State-owned rail system (Vermont Agency 

of Natural Resources, 2012). About 73,000 customers lost 

electric power. By November 15, 2011, significant damage 

to about 1,500 residences had been documented by FEMA, 

and 7,215 individuals and families had registered for FEMA 

assistance (Vermont Agency of Natural Resources, 2012). 

Other significant impacts were the displacement of 1,500 

State employees from their workplaces, damage to two fish 

hatcheries, the issuance of “boil-water” notices affecting 

16,590 people using about 30 public-water systems, compromised operations at 17 municipal wastewater-treatment 

facilities, and the filing of more than 450 farm loss claims 

with the U.S. Department of Agriculture to compensate for 

damage to approximately 20,000 acres of farmland at a loss of 

more than $10 million statewide (Vermont Agency of Natural 

Resources, 2012). 

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73°0' 72°0'

45°0'

44°0'

43°0'

VERMONT

NEW 

YORK

NEW HAMPSHIRE

MASSACHUSETTS

CANADA

Base from U.S. Geological Survey Data, 

1:2,000,000 digital line graphs,

GCS North American 1983 projection

EXPLANATION

Precipitation amounts, in inches

Less than 2

2.01 to 3

3.01 - 4

4.01 - 5

5.01 - 6

6.01 - 7

7.01 - 8

8.01 - 9

9.01 - 11

11.1 - 13

Path of tropical storm Irene

! Precipitation data points

UNITED STATES

0 20 40 MILES

0 20 40 KILOMETERS

Figure 3. Rainfall totals and path of tropical storm Irene, August 28–29, 2011, in Vermont.
Introduction 

7

Table 3. Peak streamflows and stages compared to historical peaks for U.S. Geological Survey gaging stations in and near Vermont, August 27–31, 2011.[ft, feet; ft3/s, cubic feet per second; mi2, square miles; USGS, U.S. Geological Survey; --, no data]

Reference 

number, as 

shown on 

figure 1

USGS 

streamgage 

number

USGS streamgage name

Drainage 

area, 

in mi2

Highest peak, August 27–31, 2011 Historical peaks

Date Stage, in ft Stream discharge, in ft3/s Rank Maximum streamflow discharge, in ft3/s Year Number of years of record

NEW HAMPSHIRE

10 01144500 Connecticut River at West Lebanon 4,092 8/29 29.66 105,000 4 136,000 1927 96

11 01154500 Connecticut River at North Walpole 5,493 8/29 31.38 99,700 1 97,000 1953 69

VERMONT

12 01133000 East Branch Passumpsic River near East Haven 54 8/28 9.79 3,250 3 4,450 1973 5013 01139000 Wells River at Wells River 98 8/28 9.03 5,170 2 5,970 1973 6914 01142500 Ayers Brook at Randolph 31 8/28 15.04 3,920 1 3,480 1973 7115 01144000 White River at West Hartford 690 8/29 28.36 90,100 2 120,000 1927 9416 01153550 Williams River near Rockingham 112 8/28 17.94 21,300 1 11,500 1987 2317 01154000 Saxtons River at Saxtons River 72 8/28 19.58 21,600 1 9,620 1936 5218 01334000 Walloomsac River near North Bennington 111 8/28 12.82 9,420 1 8,450 1938 7819 04280000 Poultney River below Fair Haven 187 8/29 23.28 12,800 2 14,800 1945 80

1 04282000 Otter Creek at Center Rutland 307 8/29 17.43 15,700 1 13,700 1938 812 04286000 Winooski River at Montpelier 397 8/28 19.05 14,600 4 57,000 1927 94

20 04287000 Dog River at Northfield Falls 76 8/28 17.26 22,200 1 10,600 1973 75

3 04288000 Mad River near Moretown 139 8/28 19.26 24,200 1 23,000 1927 824 04290500 Winooski River near Essex Junction 1,044 8/29 22.18 35,000 3 113,000 1927 825 04292000 Lamoille River at Johnson 310 8/29 16.54 13,100 3 19,000 1995 837 04293000 Missisquoi River near North Troy 131 8/29 13.93 10,900 2 11,500 2002 78

21 04296000 Black River at Coventry 142 8/29 8.20 4,070 1 3,740 1976 58
8 High-water marks from flooding in Lake Champlain, April–June 2011, and Tropical Storm Irene, August 2011, in Vermont

Methods

Flagging and Documenting High-Water Marks

From August 18–23, 2011, 39 HWMs from the Lake 

Champlain flooding in April through June 2011 were flagged 

in Addison, Chittenden, Franklin, and Grand Isle Counties 

(fig. 1). The HWMs associated with the Lake Champlain 

flooding marked flood crests of the lake; flooding along 

streams was not flagged. Marks generally were flagged at 

access areas or boat launches on the Vermont side of the lake. 

From September 2–October 18, 2011, 30 USGS personnel identified and flagged 1,138 HWMs associated with 

tropical storm Irene (figs. 1 and 4). HWMs were flagged in all 

counties except Essex and Lamoille; the HWMs ranged from 

2 in Franklin County to 435 in Windsor County. HWMs were 

flagged on 96 named streams or tributaries to named streams 

and at 6 confluences.

Each field crew consisted of at least one technician who 

had experience in finding and flagging HWMs according to 

general USGS guidelines for identifying, rating, and classifying these marks (Benson and Dalrymple, 1967). HWMs 

were rated according to a quantitative accuracy scale (table 

4; modified from Lumia and others, 1987). A system was 

established for naming HWMs and recording HWM information so that data recorded by field crews would be consistent. 

Areas targeted for flagging HWMs after tropical storm Irene 

were upstream and downstream from all structures (road and 

railroad bridges, culverts, and dams) on all stream reaches that 

had experienced major flooding in the State.

Each field crew had a preprogrammed Trimble Nomad 

personal digital assistant (PDA) equipped with a Global 

Positioning System (GPS) to determine latitude and longitude 

information. With the identification of each unique HWM, 

a text file with descriptive information and the GPS location was generated and saved to the PDA. The GPS locations 

were stored, organized, and displayed using Trimble AgGPS 

EZ–Map software (Trimble Navigation Limited, 2006). At 

least two photographs were taken for documentation that also 

could be used later by the survey crews to help find the HWM. 

Typically, one of the photographs was at close range and the 

second at some distance to provide context. In some cases, 

a backup latitude and longitude (in addition to that saved on 

the PDA) was generated and either saved in paper files or in a 

separate electronic device.

Surveying High-Water Marks

Surveying of HWM locations was performed by a 

Virginia company, Dewberry, during the 2012 field season 

through a contract with USGS. Dewberry found 74 percent of 

the HWMs that were flagged. A Microsoft Excel spreadsheet 

(appendix 2) listing the surveyed horizontal coordinates (referenced to the Vermont State Plane Coordinate System and the 

Table 4. Quantitative scale to rate 

accuracy of high-water marks.

[±, 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

North American Datum of 1988 (NAD 83)) and vertical elevations (referenced to the North American Vertical Datum of 

1988 (NAVD 88) in feet) for each HWM, and a survey report 

with metadata as well as a summary of the surveying segment 

of the project (appendix 1) were provided to the USGS (Dewberry, written commun., 2012). An explanation (for example, 

“missing/unable to locate” or “destroyed”) was provided in the 

spreadsheet for the 26 percent of HWMs that were not found. 

Most of this 26 percent not found can be attributed to the delay 

between the time of flagging (generally September or October 

2011) and that of surveying (summer 2012). Some of the data 

from the spreadsheet, including descriptions of the high-water 

marks and elevations, also are displayed on a clickable map in 

appendix 3. 

Summary

Vermont experienced two historic flood events in 2011. 

The wettest spring on record in Burlington (19.94 inches 

of precipitation from March through May) resulted in a 

new record for stage (103.27 feet on May 6, referenced to 

the National Geodetic Vertical Datum of 1929) at the Lake 

Champlain at Burlington, Vermont, gaging station (04294500). 

The water level in Lake Champlain remained above National 

Weather Service flood stage of 100 feet for 68 days between 

April 13 and June 18. Presidential declarations of major disasters were made in June, July, and November 2011 as the result 

of the severe storms and flooding during April through June 

2011 around Lake Champlain.

From August 28–29, 2011, record rainfall from tropical 

storm Irene (3 to more than 7 inches statewide) caused extensive flooding throughout Vermont on a scale not experienced 

since 1927. Eighty-eight percent of municipalities in the State 

suffered damage. New record streamflows were recorded at 

nine sites in and near Vermont and nine other sites had peak 

streamflows among the top four of record. A fourth presidential declaration of disaster was made in Vermont following 

tropical storm Irene, which (with subsequent amendments) 
Summary 9

A B

C

D

Figure 4. High-water marks associated with flooding from tropical storm Irene in August 2011 in Vermont. These photographs 

represent typical manifestations of high-water marks and are ordered generally from best to poorest quality: A, mud line on a building; 

B, debris line on a fence; C, silt line on a tree; and D, wash line on the ground.

authorized individual assistance for 12 counties, public assistance for all 14 counties, and hazard mitigation statewide.

High-water marks (HWMs) from the spring and August 

floods in Vermont were flagged by the U.S. Geological Survey 

(USGS) during the 2011 field season. The highest levels 

of Lake Champlain from the May 2011 flood peak were 

documented with 39 HWMs in four counties. These HWMs 

generally were identified and flagged at lake access areas and 

boat launches.

Flood levels of Vermont rivers after tropical storm Irene 

were documented with 1,138 HWMs in 12 counties. These 

HWMs generally were identified and flagged upstream and 

downstream from all structures in stream reaches that were 

heavily impacted by flooding. A system of protocols for identifying and recording HWM information using personal digital 

assistant devices equipped with a global positioning system 

was developed to ensure consistent data collection among field 

crews. The success rate for finding flagged HWMs by the contracted survey crews was 74 percent. The surveyors produced 

a spreadsheet with surveyed horizontal coordinates and vertical elevations and a report describing methods and metadata. 

In the next phase of this project, survey data from these flood 

elevations will be used by the USGS to generate flood inundation maps for selected study reaches in Vermont.
10 High-water marks from flooding in Lake Champlain, April–June 2011, and Tropical Storm Irene, August 2011, in Vermont

References Cited

Benson, M.A., and Dalrymple, Tate, 1967, General field and 

office procedures for indirect discharge measurements: U.S. 

Geological Survey Techniques of Water-Resources Investigations, book 3, chap. A1, 30 p.

Lake Champlain Basin Program, 2011, 2011 Lake Champlain 

flood update, draft 5/27/2011: Lake Champlain Basin Program, accessed November 13, 2012, at http://www.lcbp.org/

PDFs/2011_flood_presentation.pdf.

Lake Champlain Basin Program, 2012, Lake Champlain basin 

flood resilience conference summary: Lake Champlain 

Basin Program, accessed November 14, 2012, at http://

www.lcbp.org/PDFs/2012FloodConference/June_Conf_

Summary.pdf.

Lumia, Richard, Burke, P.M., and Johnston, W.H., 1987 

Flooding of December 29, 1984, through January 2, 1985, 

in northern New York state, with flood profiles of the 

Black and Salmon rivers: U.S. Geological Survey WaterResources Investigations Report 86–4191, 53 p.

National Weather Service, 2011, Preliminary hurricane/tropical storm Irene weather summary for the north country: 

National Weather Service, accessed November 13, 2012, at 

http://www.erh.noaa.gov/btv/events/Irene2011/.

Trimble Navigation Limited, 2006, EZ–Map software: Trimble Navigation Limited fact sheet, accessed November 26, 

2012, at http://www.patinc.info/product%20pdfs/ezmap.pdf.

U.S. Geological Survey, 2011, High flows in New Hampshire 

and Vermont from tropical storm Irene estimated: U.S. 

Geological Survey, accessed November 13, 2012, at http://

nh.water.usgs.gov/WhatsNew/Irene_aug2011.htm.

U.S. Geological Survey, 2012, Retrieve summary of recent 

flood and high flow conditions: U.S. Geological Survey 

WaterWatch, accessed November 13, 2012, at http://

waterwatch.usgs.gov/index.php?id=wwdp2.

Vermont Agency of Natural Resources, 2012, Lessons 

from Irene—Building resiliency as we rebuild: Vermont 

Agency of Natural Resources, accessed November 13, 

2012, at http://www.anr.state.vt.us/anr/climatechange/

irenebythenumbers.html.

Vermont State Climate Office, 2011a, Climate impacts 

summary, March 2011: Vermont State Climate Office, 

accessed January 28, 2013, at http://www.uvm.

edu/~vtstclim/?Page=climate_impacts.html.

Vermont State Climate Office, 2011b, Climate impacts 

summary, May 2011: Vermont State Climate Office, 

accessed November 13, 2012, at http://www.uvm.

edu/~vtstclim/?Page=climate_impacts.html.

WCAX–TV, 2011, Flooding forces evacuations in central 

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Appendixes 11

Appendix 1. Report prepared by Dewberry to document 

the Vermont high-water mark survey, September 19, 2012.

[Available separately at http://pubs.usgs.gov/ds/763/]

Appendix 2. Elevations of high-water marks from flooding 

in Lake Champlain from April through June 2011 and 

tropical storm Irene, August 28–29, 2011, in Vermont.

[Available separately at http://pubs.usgs.gov/ds/763/]

Appendix 3. Map of high-water marks from flooding in 

Lake Champlain from April through June 2011 and tropical 

storm Irene, August 28–29, 2011, in Vermont.

[Available separately at http://pubs.usgs.gov/ds/763/]

Prepared by the Pembroke Publishing Service Center.

For more information concerning this report, contact:

Director

U.S. Geological Survey

New Hampshire-Vermont Water Science Center

331 Commerce Way, Suite 2

Pembroke, NH 03275

dc_nh@usgs.gov

or visit our Web site at:

http://nh.water.usgs.gov/
Medalie and Olson—High-Water Marks From Flooding in Lake Champlain from April through June 2011 and Tropical Storm Irene in August 2011 in Vermont—Data Series 763