U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2009–5102

Prepared in cooperation with the 

Federal Emergency Management Agency

Flood of April 2007 in Southern Maine
Cover. Photograph of Great Works River at Emery Bridge Road washout, South Berwick, Maine, April 2007.
Flood of April 2007 in Southern Maine

By Pamela J. Lombard

Prepared in cooperation with the Federal Emergency Management Agency

Scientific Investigations Report 2009–5102

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Lombard, P.J., 2009, Flood of April 2007 in southern Maine: U.S. Geological Survey Scientific Investigations Report 

2009–5102, 34 p., available only online at http://pubs.usgs.gov/sir/2009/5102.
iii

Contents

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

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

Antecedent Hydrologic Conditions.............................................................................................................4

Soil Moisture..........................................................................................................................................4

Precipitation...........................................................................................................................................4

Streamflow.............................................................................................................................................4

Storm Characteristics ...................................................................................................................................4

Precipitation Amounts .........................................................................................................................4

Rainfall Frequency................................................................................................................................4

Peak Stream Elevations and Flows.............................................................................................................8

Peak Water-Surface Elevations .........................................................................................................8

Peak Streamflows.................................................................................................................................8

Determination of Peak Streamflows through Stage/Discharge Rating Curves ..............13

Determination of Peak Streamflows through Hydraulic Modeling using 

Indirect Methods..........................................................................................................13

Flow-Frequency Analyses.................................................................................................................14

Characteristics of the Flood in the Mousam River Watershed............................................................16

Square Pond ........................................................................................................................................16

Mousam Lake ......................................................................................................................................19

Estes Lake ............................................................................................................................................19

Combined Impact of Dams ................................................................................................................19

Historical Floods in Southern Maine ........................................................................................................20

Comparison of the April 2007 Flood Data to Flood Insurance Studies................................................21

Summary and Conclusions.........................................................................................................................23

Acknowledgments.......................................................................................................................................24

References Cited..........................................................................................................................................24
iv

Tables

1. Peak water-surface elevations for April 2007 flood in York and Cumberland 

Counties, Maine ..........................................................................................................................26

2. Peak flows for selected recurrence intervals and peak flows calculated for the 

April 2007 flood in southern Maine ..........................................................................................12

3. Mousam River watershed drainage areas, streamflows, and reservoir storage, 

southern Maine...........................................................................................................................18

4. April 2007 peak flows in comparison to May 2006 peak flows in southern Maine..........20

5. Relation of computed April 2007 flood discharges and high-water mark elevations 

to flood-insurance study data for selected locations in southern Maine.........................22

Figures

1. Photograph showing Keay Brook washout of Ridlon Road, April 2007, 

Berwick, Maine.............................................................................................................................2

2. Map showing location of study area and data-collection sites, southern Maine.............3

3. Map showing total precipitation for 3-day period from April 15 through 18, 2007, 

southern Maine and New Hampshire (from Jensenius and others, 2007)..........................5

4. Map showing 24-hour rainfall in southern Maine and New Hampshire from 7:00 a.m. 

April 15 through 7:00 a.m. April 16, 2007....................................................................................6

5. Map showing change in water content in snowpack from April 10 through 19, 2007, 

southern Maine.............................................................................................................................7

6. Photograph showing marker indicating high-water elevation, April 2007 flood, 

southern Maine.............................................................................................................................9

7. Photograph showing marker at debris line on bark of tree indicating high-water 

elevation, April 2007 flood, southern Maine.............................................................................9

8. Photograph showing debris line indicating high-water elevation along Little River 

near Longswamp Road, April 2007 flood, Berwick, Maine..................................................10

9. Map showing location of sites where high-water marks were surveyed following 

the April 2007 flood in southern Maine ...................................................................................11

10. Photograph showing streamflow measurement taken with acoustic Doppler 

current profiler on Nezinscot River, April 17, 2007, Turner, Maine .....................................13

11. Map showing peak streamflow recurrence intervals for selected sites, April 2007 

flood, southern Maine................................................................................................................15

12. Map showing location of dams and U.S. Geological Survey streamflow-gaging 

stations in the Mousam River watershed, southern Maine ................................................17
v

Conversion Factors and Datum

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

Area

square mile (mi2) 2.590 square kilometer

Volume

cubic foot (ft3) 0.02832 cubic meter

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

 °C=(°F–32)/1.8

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).

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

Up to 8.5 inches of rain fell from April 15 through 18, 

2007, in southern Maine. The rain—in combination with up to 

an inch of water from snowmelt—resulted in extensive flooding. York County, Maine, was declared a presidential disaster 

area following the event. 

The U.S. Geological Survey, in cooperation with the 

Federal Emergency Management Agency (FEMA), determined 

peak streamflows and recurrence intervals at 24 locations and 

peak water-surface elevations at 63 sites following the 

April 2007 flood. Peak streamflows were determined with 

data from continuous-record streamflow-gaging stations where 

available and through hydraulic models where station data 

were not available. The flood resulted in peak streamflows 

with recurrence intervals greater than 100 years throughout 

most of York County, and recurrence intervals up to 50 years 

in Cumberland County. Peak flows for selected recurrence 

intervals varied from less than 10 percent to greater than 

100 percent different than those in the current FEMA floodinsurance studies due to additional data or newer regression 

equations. Water-surface elevations observed during the 

April 2007 flood were bracketed by elevation profiles in 

FEMA flood-insurance studies with the same recurrence 

intervals as the recurrence intervals bracketing the observed 

peak streamflows at seven sites, with higher elevation-profile 

recurrence intervals than streamflow recurrence intervals at 

six sites, and with lower elevation-profile recurrence intervals 

than streamflow recurrence intervals at one site.

The April 2007 flood resulted in higher peak flows and 

water-surface elevations than the flood of May 2006 in coastal 

locations in York County, and lower peak flows and watersurface elevations than the May 2006 flood further from 

the coast and in Cumberland County. The Mousam River 

watershed with over 13 dams and reservoirs was severely 

impacted by both events. Analyses indicate that the April 2007 

peak streamflows in the Mousam River watershed occurred 

despite the fact that up to 287 million ft3 of runoff was stored 

by 13 dams and reservoirs. 

Introduction

The April 2007 storm, which is commonly referred to 

in Maine as the Patriots’ Day Storm, produced strong winds, 

tornadoes, high waves, beach erosion, and riverine and coastal 

flooding in communities from South Carolina to Maine from 

April 15 through 18, 2007. The storm, resulting from a major 

low-pressure system, reached peak intensity on April 16 off 

the coast of New Jersey but still produced up to 8.5 in. of rain 

in southern Maine (National Weather Service, written commun., 2007). The storm produced hurricane-force winds and 

extreme rainfall in Maine, causing storm surges and flooding 

in coastal areas and extensive flooding of streams and rivers 

inland. The State of Maine declared a state of emergency as a 

result of the flooding caused by the Patriots’ Day Storm. 

Federal disaster areas were declared in Androscoggin, 

Cumberland, Franklin, Hancock, Kennebec, Knox, Lincoln, 

Oxford, Sagadahoc, Somerset, Waldo, Washington, and 

York Counties. The Maine Emergency Management Agency 

(MEMA) estimated damages to public infrastructure associated with the Patriots’ Day Storm at $45 million, including 

$31.5 million to roads alone (fig. 1). Damage to private homes 

and property also was extensive. Over $16.2 million was spent 

by the Federal Emergency Management Agency (FEMA) on 

1,600 damage-repair projects in the 13 counties associated 

with the April 2007 flood (Federal Emergency Management 

Agency, written commun., 2007). 

The documentation of peak flood-water heights and 

peak-streamflow magnitudes and frequencies associated with 

extreme events provides water-resource managers and emergency-management workers with essential data for the delineation of floodplains necessary for accurate land-use planning 

and for flood-mitigation decisions. Peak-flood data are important for the calibration of models used to establish and assess 

100-year and 500-year floodplain limits and profiles. 

The magnitude and frequency of flooding are critical 

engineering information used by the Maine Department of 

Transportation and local public-works officials to accurately 

size new bridges and culverts. An oversized bridge will cost 

additional money to build, and an undersized bridge will 

increase the risk of the structure getting damaged or destroyed 

during its design life. Flood analyses guide improvements 

to emergency-action plans for affected communities. Flood 

documentation in a disaster area is crucial for the development 

of mitigation measures to prevent future flood losses and for 

appropriate allocation of disaster-assistance funding when the 

next extreme event occurs.

The U.S. Geological Survey (USGS), in cooperation 

with FEMA, began a study in 2007 to document the antecedent conditions, precipitation, and streamflows associated with 

the severe riverine flooding in Maine in April 2007 caused 

Flood of April 2007 in Southern Maine

By Pamela J. Lombard
2 Flood of April 2007 in Southern Maine

by the Patriots’ Day Storm. Initially, the USGS identified, 

flagged, and surveyed high-water marks (HWMs) in southern 

Maine and provided FEMA with locations and elevations for 

the HWMs in June 2007. As a part of this preliminary work, 

the USGS computed peak flows and recurrence intervals for 

the Mousam River near West Kennebunk and for the Little 

Ossipee River near South Limington associated with the 

April 15 through 18, 2007 extreme flooding in these areas. 

Recurrence intervals between 100 and 500 years were documented at the above locations on the Mousam and Little 

Ossipee Rivers for the April 2007 flood (Hodgkins and 

others, 2007).

The April 2007 flood affected many of the same 

locations and rivers as the May 2006 flood in York County. 

Peak streamflows and recurrence intervals for 9 streams and 

peak water-surface elevations at 25 sites were published for 

the May 2006 flood (Stewart and Kempf, 2008). One stage/

discharge rating extension and six calibrated hydraulic models 

developed after the May 2006 flood were also used to compute 

peak discharges for the April 2007 flood. In addition, 11 new 

hydraulic models and 5 new rating extensions were developed 

specifically for this study. 

Severe flooding occurred in the Mousam River watershed (fig. 2) during both the May 2006 and April 2007 floods. 

This watershed is characterized by numerous small dams and 

reservoirs, and has the potential to be highly regulated. It was 

unclear to water-resource managers how much of an impact 

the dams could have on events equivalent to or greater than 

the 100-year event. This study includes estimates of how the 

storage capacities, inflows, and outflows of the many reservoirs might have interacted cumulatively to affect flooding 

in the Mousam River watershed during the April 2007 flood. 

Reservoir volumes and surface areas and dam dimensions 

were obtained from the Maine Department of Environmental 

Protection (MaineDEP) Emergency Action Plans and include 

many assumptions. 

Figure 1. Keay Brook washout of Ridlon Road, April 2007, Berwick, Maine.
Introduction 3

Figure 2. Location of study area and data-collection sites, southern Maine.

York

Wells

Gray

Standish

Saco

Acton

Hiram

Lebanon

Gorham

Sebago

Sanford

Lyman

Hollis

Casco

Buxton

Waterboro

Porter

Naples Denmark

Windham

Parsonsfield

Berwick

Alfred

Durham

Raymond

Baldwin

Limington

Brownfield

Shapleigh

Newfield

Scarborough

Freeport

Eliot

Limerick

Falmouth

Biddeford

Kennebunk

Pownal

Bridgton

Arundel

New Gloucester

Cornish

Poland

North

Berwick

Fryeburg Auburn

Dayton

South Berwick

Portland

Lisbon

Cumberland

North

Yarmouth

Yarmouth

Otisfield

Westbrook

Kennebunkport

Cape

Elizabeth

South

Portland

Ogunquit

Lewiston

Old Orchard

Beach

Harrison

Brunswick

Kittery

Snow survey site

and identifier

Precipitation station

and identifier

Streamflow gagingstation and number—

See table 1

EXPLANATION

14

Hollis

Mousam River watershed

Study area

MAINE

71° 70°15'

44°

43°15'

HOLLIS

Cornish

CORNISH

Newfield

West

Kennebunk

Eliot

Hollis

Cumberland

Gray

SANFORD

2

22

8

58

55

49

42

63

33

28

12

16

13

15

3

62

37

39

60

59

38

51

57

17

61

Base from U.S. Geological Survey and

Maine Office of Geographic Information System digital files,

North American Datum 83, Universal Transverse Mercator grid, Zone 19 NEW HAMPSHIRE MAINE

Atlantic

Ocean

0

0

10 MILES

10 KILOMETERS

HOLLIS
4 Flood of April 2007 in Southern Maine

Antecedent Hydrologic Conditions

Hydrologic conditions in the weeks and months prior to 

a flood can have a substantial impact on peak streamflows and 

peak elevations resulting from the flood. Antecedent hydrologic conditions that can affect the severity of a flood include 

stream stage and discharge, percent soil saturation and (or) 

degree of frozen soils, and ground-water levels. Relatively little hydrologic information that describes hydraulic conditions 

prior to the April 2007 flood in southern Maine is available; 

however, soil moisture, precipitation, and streamflow records 

that are available are summarized below. 

Soil Moisture

Soil moisture was from 0 to 40 mm above average in 

southern Maine from December 2006 through February 

2007 (accessed from the National Oceanic and Atmospheric 

Administration National Weather Service at http://www.nws.

noaa.gov/ost/climate/STIP/nasm_fcst_07.htm on May 5, 

2009). In March 2007, soil moisture was average in York and 

Cumberland Counties, Maine. In April 2007, most of Maine 

had soil moisture that was 20 mm above normal, but this 

period includes the precipitation from the Patriots’ Day Storm. 

Precipitation

Portland, Maine, received 14.3 and 14.1 in. of snowfall 

in February and March 2007, respectively, which was 1.5 and 

1.1 in. above normal for those months based on 126 years of 

record (National Oceanic and Atmospheric Administration, 

2002). On April 9, 2007, a thin, wet snowpack covered the 

ground in the Mousam and Little Ossipee River Basins. Snowpack was measured at four locations in or near the basins on 

April 9, 2007, as part of the Maine Cooperative Snow Survey 

program—West Kennebunk, Newfield, Hollis, and Cornish 

(fig. 2). Snowpack depths ranged from 2.4 to 5.3 in. and had 

an equivalent water content of 0.8 to 1.5 in. 

Portland, Maine, received 3.01 in. of rain in March 2007, 

which was 1.13 in. below normal (National Oceanic and 

Atmospheric Administration, 2002) based on 137 years of 

precipitation record at this site. Gray, Maine, received 3.94 in. 

of rain during March 2007 (National Weather Service, 2008).

Streamflow

The largest streamflows in Maine typically occur in the 

spring (March, April, and May) when rain falls on a dense 

(ripe) snowpack or on saturated soils. Streamflows recede as 

snowmelt ends and evapotranspiration increases. In the spring 

of 2007, there were no active continuous-record streamflowgaging stations in York County, Maine. March 2007 mean 

streamflow on the Saco River at Cornish in Cumberland 

County, Maine (site 62, fig. 2), was 2,490 ft3/s, which is in 

the normal range for March. March 2007 mean streamflow 

on Stony Brook at East Sebago, Maine (also in Cumberland 

County) (site 61, fig. 2), was 2.37 ft3/s. Although this is in the 

normal range for March, there are only 12 years of record at 

this site. On the basis of the limited data available, antecedent streamflow conditions were in the normal range in March 

2007 in southern Maine.

Storm Characteristics

Precipitation Amounts

Large amounts of rainfall fell in southern Maine from 

April 15 through 18, 2007. Rainfall totals for the 3-day storm 

were 8.42, 8.56, 7.08, and 6.83 in. at precipitation stations in 

Eliot, Sanford, Hollis, and Cornish, respectively (Jensenius 

and others, 2007) (figs. 2 and 3). Twenty-four hour precipitation totals from 7:00 a.m. Sunday, April 15, through 7:00 a.m. 

Monday, April 16, at these same locations were 6.93, 5.92, 

4.02, and 3.2 in., respectively (fig. 4). Maximum 24-hour 

precipitation during the Patriots’ Day Storm occurred from the 

afternoon of April 15 through the afternoon of April 16, 2007, 

and was calculated to be 7.58, 4.97, and 4.60 in. at continuously recording precipitation stations in Sanford, Hollis, and 

Cornish, respectively (T. Hawley, National Weather Service, 

written commun., 2007; Hodgkins and others, 2007). 

Snowpack was measured at West Kennebunk, Newfield, 

Hollis, and Cornish in York and Cumberland Counties on 

April 19, 2007 (snowpack was measured at the same locations 

on April 9) (see section Antecedent Hydrologic Conditions) 

above. There was either no snow or trace amounts of snow 

at these sites on April 19 (Maine Cooperative Snow Survey, 

2007). The reduction in snowpack water content from April 9 

to 19 averaged 1 in. throughout most of York and Cumberland 

Counties. Extreme northern parts of this region had no 

substantial change in snowpack water content (fig. 5). A storm 

on April 12 and 13 may have changed the equivalent water 

content in the snowpack prior to the April 2007 flood 

(T. Hawley, National Weather Service, written commun., 

2007). The reduction in snowpack water content that took 

place during the April 2007 flood augmented runoff from 

storm precipitation totals in streams. 

Rainfall Frequency

The Atlas of Precipitation Extremes for the Northeastern 

United States and Southeastern Canada contains maps with 

recurrence-interval isolines for 1-, 2-, 4-, 7-, and 10-day 

rainfall totals (Wilks and Cember, 1993). The T-year (where T 

equals 100, 50, 25, 10, 5, and 2) rainfall recurrence intervals 

for southern Maine were interpolated from these maps. The 

recurrence interval is the average period of time between 

rainfalls that are greater than or equal to a specified magnitude. 

The 100-year rainfall is the rainfall that would be equaled or 
Storm Characteristics 5

Figure 3. Total precipitation for 3-day period from April 15 through 18, 2007, southern Maine and New Hampshire 

(from Jensenius and others, 2007).

0

0

10

10

20 MILES

20 KILOMETERS

MAINE

NE

W HAMPSHIRE

MASSACHUSETTS

CANADA

NEW HAMPSHIRE

7

5

3.4

3.7

5.4

5.6

4.5

5.71

3.51

5.52

6.25

5.43

5.86

3.29

4.52

4.47

5.98

4.58

4.71

7.21

3.69

5.61

2.27 5.79

6.97

6.38

6.44

4.85

6.11

8.55

1.79

5.61

6.51

5.26

5.17

4.23

6.12

8.56

5.96

5.88

4.35

5.97

5.48

7.08

6.77

4.86

5.35

6.07

8.42

6.61

6.83

5.69

5.74

5.88

4.04

5.25

4.37

EXPLANATION

Line of equal rainfall, in inches

Town boundary

6.44

Atlantic

Ocean

71° 70°

44°

43°

National Weather Service station

location and rainfall amount,

in inches

Base from U.S. Geological Survey and

Maine Office of Geographic Information System digital files,

North American Datum 83, Universal Transverse Mercator grid, Zone 19

5

4

5

5

6

5

4

5

6

6

5

8

7

6

6

8

5

4

5

4

2

3

8

8

5

5

5

4

5

5

6

5

4

4

5

6

6

6

5

8

7

7

7

6

6

8

5

4

5

4

4

3

8

8
6 Flood of April 2007 in Southern Maine

Figure 4. Twenty-four-hour rainfall in southern Maine and New Hampshire from 7:00 a.m. April 15 through 7:00 a.m. 

April 16, 2007.

3

EXPLANATION

National Weather Service station

location and rainfall amount,

in inches 

Line of equal rainfall, in inches

Town boundary

0.37

3

Base from U.S. Geological Survey and

Maine Office of Geographic Information System digital files,

North American Datum 83, Universal Transverse Mercator grid, Zone 19

2

3

4

5

5

2

5

1

2

2

3

2

2

5

Atlantic

Ocean

MAINE

NEW HAMPSHIRE

VERMONT

MASSACHUSETTS

VERMONT

CANADA

CANADA

3.3

2.9

3.9

4.3

3.6

0.8

0.3

1.6

2.3

1.3

2.7

1.2 1.2

1.5

0.3

2.7

3.2

1.05

1.43

2.17

0.37

0.61

1.81

3.82

0.61

2.25

2.34

2.62

1.22

2.18 1.22

0.29

1.41

4.56

0.82

4.34

0.82

1.38

2.93

4.94

3.32

4.26

2.76

2.38

1.68

1.14

1.07

3.03

3.63

2.58

2.74 2.51

0.71

2.46

3.73

1.68

2.49

0.75

2.09

1.29

5.92

1.54 2.17

0.85

3.45

0.63

1.91

2.08

1.08

1.11

1.68

0.27

0.95

2.51

2.51

1.58

3.78

4.02

2.37

0.38

0.93

2.73

3.18

1.68

0.61

2.68

4.36

2.89

0.43

2.37

1.35

0.76

1.87

2.16

1.39 1.92

1.59

1.17

0.56

2.12

2.7

6.93

4.37

4.35

72° 69°

46°

43°

MAINE

0

0

50 MILES

50 KILOMETERS

1

1

2

3

4

5

6

2

5

1

2

2

3

2

2

2

1

3

3

4

4

5

2

3

4

6

2

5

1

2

2

3

2

2

2

2

1

1

3

3

4

4

5

1
Storm Characteristics 7

Figure 5. Change in water content in snowpack from April 10 through 19, 2007, southern Maine.

EXPLANATION

-3 inches

-2 inches

-1 inch

Less than +/- 1 inch

+ 1 inch

Change in water content

in snowpack

0

0

200 MILES

200 KILOMETERS

100

71° 70°

44°

43°

York County 

Kittery

Biddeford

Portland

Cumberland County

Snow survey site

NEW HAMPSHIRE

MAINE

Base from U.S. Geological Survey and

Maine Office of Geographic Information System digital files,

North American Datum 83, Universal Transverse Mercator grid, Zone 19

DATA CONTRIBUTORS: U.S. Geological Survey,

National Weather Service and SAPPI

MASSACHUSETTS
8 Flood of April 2007 in Southern Maine

exceeded on average once every 100 years. This means there 

is a 1.0 percent chance that a rainfall of this magnitude will be 

equaled or exceeded in any given year. The 100-year rainfall 

totals for 2-, 4-, 7-, and 10-day periods in southern Maine are 

8, 9, 11, and 12 in., respectively (Wilks and Cember, 1993). 

The average rainfall, based on the National Weather Service 

precipitation records during the Patriots’ Day Storm in April 

of 2007 was roughly equivalent to the 100-year recurrence 

interval for 2-day rainfall totals near Sanford, Maine (fig. 2).

Peak Stream Elevations and Flows

The rain that fell in York and Cumberland Counties 

between April 15 and 18, 2007, in addition to up to an inch 

of equivalent water from snowmelt, resulted in extreme 

water-surface elevations and streamflows in rivers in parts 

of southern Maine. Peak water-surface elevations and the 

magnitude and recurrence interval of peak streamflows are 

described below. 

Peak Water-Surface Elevations

Peak water-surface elevations are based on recorded 

stage at continuously recording streamflow-gaging stations 

or crest-stage gaging stations where available and on HWMs 

identified using the techniques of Benson and Dalrymple 

(1967) where station data are not available. No continuousrecord streamflow-gaging stations on unregulated streams 

were in operation in April 2007 in the regions of York and 

Cumberland Counties most heavily impacted by the flood. 

The Presumpscot River at Westbrook, Maine (USGS station 

number 01064118, site number 63, fig. 2), crested at 

38.0 ft NAVD 88 at 7:45 p.m. on April 16, 2007, 10 ft above 

the National Weather Service flood stage of 27.7 ft NAVD 88. 

The Presumpscot River is regulated at the outlet of Sebago 

Lake. The Saco River at Cornish (USGS station number 

01066000, site number 62, fig. 2) and Stony Brook at East 

Sebago (USGS station number 01063310, site number 61, 

fig. 2) are on the outskirts of the region affected by the April 

2007 flood. Stony Brook at East Sebago crested at 282.5 ft 

NAVD 88 at 1:00 p.m. on April 16, 2007, and the Saco River 

at Cornish crested at 274.1 ft NAVD 88 at 11:15 p.m. on 

April 16, 2007 (table 1 in back of report). The Saco River at 

Cornish is regulated by several upstream power plants. Peak 

water-surface elevations were measured at Chenery Brook 

near Cumberland (USGS station number 01060070, site 

number 60, fig. 2) and unnamed brook at Gray (USGS station 

number 01059845, site number 59, fig. 2) with crest-stage 

gaging stations in operation during the April 2007 flood 

(table 1 in back of report).

HWMs such as debris lines or wash lines caused by the 

flooding event can be located, marked, and rated in the days 

following a storm (fig. 6). Debris lines usually consist of fine 

material such as silt, hemlock needles, or seeds deposited by 

peak water surfaces on trees (fig. 7), bridge abutments, buildings, or streambanks (fig. 8). Wash lines are defined by the 

removal or washing away of soil, debris, and leaves by flood 

peaks. It is essential to mark all HWMs as soon as possible 

after the event because they can quickly fade or wash away in 

subsequent storms. HWMs are rated on the basis of the type 

and quality of the debris line or wash line as well as other 

corroborating evidence in the area. The accuracy of the mark 

is defined as follows: a high-water mark having an excellent 

rating is estimated to be within 0.05 ft of the actual peak water 

surface; a good mark is within 0.1 ft; a fair mark is within 

0.2 ft; and a poor mark may be greater than 0.2 ft from the true 

peak water surface during the event.

Peak water-surface elevations were determined for 

160 points at 62 sites on 33 rivers and streams in York and 

Cumberland Counties, Maine, following the April 2007 flood 

(table 1 in back of report, fig. 9). Most of the documented 

HWMs were upstream or downstream of bridges, culverts, and 

dams or at discontinued streamflow-gaging stations or creststage gaging stations. The locations of sites where HWMs 

were identified (one to four marks per site) are shown on 

figure 9, and the elevations of the HWMs are listed in 

table 1 (in back of report). All HWMs included in this report 

were referenced to NAVD 88 using High Precision Global 

Positioning System (GPS) instrumentation. At sites where a 

continuous-record streamflow-gaging station was in operation, 

peak water-surface elevations were recorded by the station 

and the identification of HWMs was unnecessary. The time of 

the peak elevation or the peak flow from the April 2007 flood 

is not known for any of the points listed in table 1 (in back 

of report) except at the continuously recording streamflowgaging stations (sites 61–63).

Peak Streamflows

Peak streamflows associated with the April 2007 flood 

were calculated at 24 sites in York and Cumberland Counties, 

Maine (table 2). Methods used to determine peak streamflows 

include the development of a relation between streamflow and 

water-surface elevation (a rating curve) at a continuous-record 

station or crest-stage station, which is periodically updated 

with streamflow measurements at or near the peak flow 

(fig. 10), and the development of hydraulic models and indirect methods at sites where a rating curve was not available or 

was unreliable for extremely high flows. Indirect methods are 

based on hydraulic modeling in which peak flows are estimated as those flows which produce modeled water-surface 

elevations that match HWMs observed in the field. Indirect 

methods of determining peak flow are based on hydraulic 

relations between flow and the geometry of the channel or 

hydraulic structures such as bridges or culverts (Benson and 

Dalrymple, 1967; Matthai, 1967). Peak streamflows were 

determined with rating curves at eight sites and hydraulic 

models and indirect methods at 16 sites in York and 

Cumberland Counties following the April 2007 flood. 
Peak Stream Elevations and Flows 9

Figure 6. Marker indicating high-water elevation, April 2007 flood, southern Maine.

Figure 7. Marker at debris line on bark of tree indicating high-water elevation, 

April 2007 flood, southern Maine.
10 Flood of April 2007 in Southern Maine

Figure 8. Debris line indicating highwater elevation along Little River near 

Longswamp Road, April 2007 flood, 

Berwick, Maine.
Peak Stream Elevations and Flows 11

Figure 9. Location of sites where high-water marks were surveyed following the April 2007 flood in southern Maine. NE

W HAMPSHIRE

MAINE

York

Wells

Gray

Standish

Saco

Acton

Hiram

Lebanon

Gorham

Sebago

Sanford

Lyman

Hollis

Buxton

Waterboro

Porter

Naples Denmark

Windham

Parsonsfield

Berwick

Alfred

Durham

Raymond

Baldwin

Limington

Brownfield

Shapleigh

Newfield

Scarborough

Freeport

Eliot

Limerick

Falmouth

Biddeford

Kennebunk

Pownal

Bridgton

Arundel

New Gloucester

Cornish

Poland

North Berwick

Fryeburg

Auburn

Dayton

South Berwick

Portland

Lisbon

Cumberland

North Yarmouth

Yarmouth

Otisfield

Westbrook

Kennebunkport

Cape

Elizabeth

South

Portland

Ogunquit

Lewiston

Old Orchard

Beach

Harrison

Brunswick

Kittery

Casco

9

8

7

6 5 4

2 3

1

62

61 60

59

58

57

56

55

54 53

52

51

50

49

48

47 46

45

44

43 42

41

40

39

38

37

36 35

34

33

32

31

28

30

29

27

25

26

24

23

22

21

19 20

18

17

16

15

14 13

12

11

10

Study area

MAINE

EXPLANATION

High-water mark and

site number—See

table 1

37

71° 70°15'

44°

43°15'

0

0

10 MILES

10 KILOMETERS

Base from U.S. Geological Survey and

Maine Office of Geographic Information System digital files,

North American Datum 83, Universal Transverse Mercator grid, Zone 19

e

Atlantic

Oc

an
12 Flood of April 2007 in Southern Maine Table 2. Peak flows for selected recurrence intervals and peak flows calculated for the April 2007 flood in southern Maine. [USGS, U.S. Geological Survey; mi2, square miles; ft3/s, cubic feet per second; yr, year; Rt., route; >, greater than; RR, railroad; nr, near; N, north; S, south; <, less than] Site num- ber USGS station number Stream and location Road crossing Drainage area (mi2) Percent- age of wetlands in basin Peak flow (ft3/s) for given recurrence interval April 2007 10-yr 50-yr 100-yr 500-yr Peak flow (ft3/s) Recurrence interval (yrs) Calculated with regression equationsa Computed with indirect methods 2 01068910b Mousam River, Sanford Rt. 4 45.0 14.4 1,610 2,310 2,640 3,420 2,400 50–100 8 Little River, Berwick Long Swamp Road 51.3 15.8 1,630 2,310 2,630 3,380 4,640 >500 12 Cape Neddick River, York Rt. 1 9.47 15.1 439 653 755 1,000 1,010 500 13 Ogunquit River, Ogunquit North Village Road 12.1 12.4 645 966 1,120 1,490 2,230 >500 15 Blacksmith Brook, Wells Rt. 1 2.01c 21.0 83.9 126 147 197 260 >500

16 Merriland River, Wells RR bridge nr Rt. 1 15.4 22.6 385 547 623 800 1,860 >50022 Kennebunk River, Kennebunk Rt. 1 42.4 11.9 1,830 2,660 3,040 3,980 5,730 >50028 Great Works River Dam, N Berwick Canal Street 36.8 17.5 1,110 1,580 1,795 2,310 2,780 >50033 Pump Box Brook, Shapleigh Rt. 11 5.72 9.81 421 651 761 1,040 1,070 50037 01066500 Little Ossipee River nr S Limingtond Sand Pond Road 168 12.2 4,280 6,770 7,990 11,300 8,220 100–50042 Stroudwater River Dam, Portland Westbrook Street 27.6 4.93 2,100 3,180 3,690 4,970 2,780 10–5049 Crooked River, Naples Edes Falls Road 129 7.61 6,030 8,680 9,900 12,900 6,150 10–5055 Pleasant River, Windham Pope Road 46.9 13.8 1,790 2,690 3,100 4,160 2,050 10–5057 01064200 Mill Brook nr Old Orchard Beache Rt. 98 1.3c 2.52 211 350 419 599 294 10–5058 Carl Branch Brook, Waterboro Straw Mill Road 3.37 12.9 223 345 403 548 500 100–50060 01060070 Chenery Brook near Cumberlande Middle Road 0.84c 6.45 114 187 224 318 101 5–10

Flood-frequency analysesf Computed with rating curves

3 01069500 Mousam River nr West Kennebunkd Whichers Mill Road 99.0 16.0 3,010 5,630 7,240 12,700 9,230 100–500

17 01069700 Branch Brook near Kennebunkg Rt. 9a 10.8 9.97 700 1,220 1,480 2,200 1,330 50–10038 01059800 Collyer Brook near Gray Rt. 202 13.8 8.57 1,030 1,450 1,650 2,120 1,450h 50

39 01060000 Royal River at Yarmouth East Main Street 141 9.28 6,610 9,510 10,800 14,100 8,160 10–5051 01065500 Ossipee River at Cornish River Road 452 9.8 7,900 11,300 12,900 16,700 9,600 10–5059 01059845 Unnamed Brook at Gray Yarmouth Road 0.35c 6.74 55.4 93.3 112 162 96 5061 01063310 Stony Brook at East Sebagog Rt. 11 0.81 13.5 119 208 253 374 125 10–5062 01066000 Saco River at Cornish Rt. 117 1,293 8.6 22,000 29,200 32,200 39,200 17,000 <5aHodgkins (1999).bThis station was started as a continuous-record station on April 9, 2008, after the 2007 flood.cThese stations have drainage areas that are outside the bounds of those for which the regression equations were designed. Errors of the estimates are unknown and could be substantial.dHodgkins and others (2007).eAlthough these stations are current or discontinued crest-stage gage stations, they do not have sufficient periods of record to create stage/discharge rating curves.fWeighted flows computed using Log Peason type III estimates based on gage data in combination with regression equation estimates.gNote short record.hExtension above highest measured flow to the 2007 high-water mark on stage/discharge rating is 293 percent.iThis station is heavily regulated and thus no estimates of discharge or recurrence interval are computed; only stage and flood stage are presented.
Peak Stream Elevations and Flows 13

Determination of Peak Streamflows through 

Stage/Discharge Rating Curves

The most reliable method for computing peak streamflows is the use of a calibrated and recently confirmed rating 

curve. The relation of stage to flow is controlled by a downstream reach or section of a channel referred to as a control. 

Depending on the stability of the river control at high flows, 

a rating can sometimes be extrapolated beyond its calibrated 

range. Historic rating curves can be used to determine peak 

discharges at inactive stations if there is evidence the site has a 

stable control and, therefore, a rating curve that is still accurate 

and applicable. To develop a rating curve, available streamflow measurements and corresponding stream elevations at a 

site are analyzed and plotted and a best-fit relation between 

them is developed (Rantz and others, 1982). 

Peak streamflows were computed at two locations from 

current rating curves using peak water-surface elevations 

obtained from continuous-record streamflow-gaging stations 

in operation during the April 2007 flood. The Saco River at 

Cornish (USGS station number 01066000) and Stony Brook 

at East Sebago (USGS station number 01063310) peaked at 

17,000 and 125 ft3/s, respectively (table 2). Times, dates, and 

elevations associated with these peak streamflows are discussed in the section (Peak Water-Surface Elevations) above. 

A peak flow of 96 ft3/s was obtained from the crest-stage 

gaging station Unnamed Brook at Gray (USGS station number 

01059845) in operation during the April 2007 flood. 

HWMs were used to estimate peak streamflows at 

several discontinued sites that had stable rating curves: 

Mousam River near West Kennebunk (USGS station number 

01069500), Branch Brook near Kennebunk (USGS station 

number 01069700), Collyer Brook near Gray (USGS station 

number 01059800), Royal River at Yarmouth (USGS station 

number 01060000), and Ossipee River at Cornish (USGS station number 01065500) (table 2). There is uncertainty with the 

rating curve and the estimated peak streamflow of 1,450 ft3/s 

at Collyer Brook near Gray because the curve was extended 

well above the highest streamflow measurement.

Determination of Peak Streamflows through 

Hydraulic Modeling using Indirect Methods

Peak streamflow was determined at the remaining 16 

sites using indirect methods based on hydraulic modeling 

(Benson and Dalrymple, 1967; Matthai, 1967). One of the 

sites was an active crest-stage gaging station (Chenery Brook 

at Cumberland) and one was a discontinued crest-stage gaging 

station (Mill Brook near Old Orchard Beach); however, these 

stations had insufficient data from which to develop stage/

discharge rating curves, and therefore, use of indirect methods 

was required to compute peak streamflows. Hydraulic models 

developed as a part of the May 2006 flood investigation to 

compute peak streamflows (Stewart and Kempf, 2008) were 

used at five of the sites. 

Figure 10. Streamflow measurement 

taken with acoustic Doppler current 

profiler on Nezinscot River, April 17, 

2007, Turner, Maine.
14 Flood of April 2007 in Southern Maine

The contraction of a stream channel by a bridge crossing can create an abrupt drop in water-surface elevation. The 

geometry of the channel and bridge, estimates of the slope 

downstream of the contraction, and roughness values are 

defined through field surveys and entered into the one-dimensional steady-flow water-surface-profile computation component of the U.S. Army Corps of Engineers step-backwater 

computer program HEC-RAS (U.S. Army Corps of Engineers, 

2004). Peak streamflows were determined to be those that 

resulted in computed water-surface elevations from the 

HEC-RAS model that matched elevations of HWMs observed 

in the field (table 2).

Flow-Frequency Analyses

Peak streamflows from the April 2007 flood were 

compared to peak flows with standard recurrence intervals at 

the same location to determine the approximate recurrence 

intervals of the April 2007 peak flows. The recurrence interval 

is the average period of time between peak flows greater than 

or equal to a specified magnitude. For example, the 50-year 

peak flow is the flow that would be exceeded or equaled on 

average of once in 50 years. This does not imply that flooding 

will happen at regular intervals. Two 50-year peak flows could 

occur in consecutive years or even the same year. In contrast, 

a second 50-year peak flow might not occur for another 

100 years. The reciprocal of the recurrence interval is called 

the annual exceedance probability—that is, the probability that 

a given peak flow will be exceeded or equaled in any given 

year. For example, the annual exceedance probability of the 

50-year peak flow is 0.02. In other words, there is a 2-percent 

chance that the 50-year peak flow will be exceeded or equaled 

in any given year. All estimates of recurrence interval have 

uncertainty associated with them. The uncertainty generally 

increases as the recurrence interval increases, especially at 

sites where the period of record is much shorter than the 

recurrence interval (Interagency Advisory Committee on 

Water Data, 1982). As the length of record at a streamflowgaging station increases, the computed recurrence intervals 

may become more accurate. Stationarity (the absence of 

trends) in peak streamflows over time is an assumption of 

the flood-flow-frequency techniques used in these analyses 

(Interagency Advisory Committee on Water Data, 1982). The 

validity of this assumption is currently being investigated for 

peak flows in Maine (G. Hodgkins, U.S. Geological Survey, 

personal commun., 2008).

The 10-, 50-, 100-, and 500-year peak flows for streamflow-gaging stations with at least 10 years of peak-flow data 

were calculated using the guidelines in Bulletin 17B of the 

Interagency Advisory Committee on Water Data (1982). A logPearson type-3 frequency analysis was fitted to the logarithms 

(base 10) of the observed annual peak flows at each station 

with sufficient data. Flood-frequency estimates from Hodgkins 

(1999) were updated for this report with an additional 9 years 

of data where available for stations in southern Maine. 

The 2007 peak on the Mousam River in West Kennebunk 

(USGS station number 01069500) of 9,230 ft3/s is the highest 

known peak for that site since 1939, although only the years 

from 1939 to 1984 were gaged continuously. The estimated 

peak at Collyer Brook near Gray (USGS station number 

01059800) of 1,450 ft3/s is the highest known peak during the 

20 years of continuous monitoring from 1965 through 1982 

and from 1999 through 2000, but it is unknown whether this 

peak was exceeded during the period from 1983 through 1998 

or from 2001 through 2006. The peak discharge of 125 ft3/s on 

Stony Brook at East Sebago (USGS station number 01063310) 

was the second-highest peak in 10 years of record; the peak 

of 130 ft3/s on September 17, 1999, was the highest (U.S. 

Geological Survey, 2008). 

The Salmon Falls River at Milton (USGS station number 

01072100) had a peak flow of 5,500 ft3/s during the April 2007 

flood with an estimated recurrence interval of 25–50 years 

(Flynn, 2008). Several New Hampshire streamflow-gaging 

stations close to the Maine border had peak-flow recurrence 

intervals of between 100 and 500 years, including the Isinglass 

River at Rochester Neck Road near Dover (USGS station 

number 01072870) and the Oyster River near Durham (USGS 

station number 01073000) (Flynn, 2008). 

Flow frequencies for sites without historical peak-flow 

data were calculated using the regression equations presented 

in Hodgkins (1999). These equations were developed using 

generalized least-squares regression procedures based on 

data from 70 USGS streamflow-gaging stations in Maine and 

eastern New Hampshire. The explanatory variables used in the 

equations were drainage area and percentage of basin covered 

by wetlands. Four of the sites at which flow frequencies 

were computed using the regression equations are outside 

the bounds for which the equations were designed—

Blacksmith Brook at Wells, Mill Brook near Old Orchard 

Beach, Unnamed Brook at Gray, and Chenery Brook at 

Cumberland. These sites all have drainage basins less than 

3 mi2, and therefore the accuracy of the estimates at these sites 

is unknown. 

Recurrence intervals for peak streamflows at six of 

the streams studied as a part of this flood analysis were 

calculated to be greater than 500 years (table 2). April 2007 

peak streamflows had recurrence intervals between 100 and 

500 years at five sites, between 50 and 100 years at two sites, 

between 10 to 50 years at nine sites, and below 10 years at 

two sites. Generally, streams in York County had recurrence 

intervals greater than 100 years; the largest recurrence 

intervals were clustered around Wells and Kennebunk, Maine. 

Streams in Cumberland County generally had peak flows with 

recurrence intervals between 10 and 50 years (fig. 11). 

For the 16 locations where peak flows were determined 

by indirect methods, historical streamflow records are not 

available. However, general comparison of the calculated peak 

flow to theoretical maximum floods is possible. Crippen and 

Bue (1977) determined envelope curves relating empirical 

maximum peak flows to drainage area to provide a guide 

for estimating the magnitude of maximum flood flows that 
Peak Stream Elevations and Flows 15

Figure 11. Peak streamflow recurrence intervals for selected sites, April 2007 flood, southern Maine.

Atlantic

Ocean

York

Wells

Gray

Standish

Saco

Acton

Hiram

Lebanon

Gorham

Sebago

Sanford

Lyman

Hollis

Casco

Buxton

Waterboro

Porter

Naples Denmark

Windham

Parsonsfield

Berwick

Alfred

Durham

Raymond

Baldwin

Limington

Brownfield

Shapleigh

Newfield

Scarborough

Freeport

Eliot

Limerick

Falmouth

Biddeford

Kennebunk

Pownal

Bridgton

Arundel

New Gloucester

Cornish

Poland

North Berwick

Fryeburg

Auburn

Dayton

South Berwick

Portland

Lisbon

Cumberland

North Yarmouth

Yarmouth

Otisfield

Westbrook

Kennebunkport

Cape

Elizabeth

South

Portland

Ogunquit

Lewiston

Old Orchard

Beach

Harrison

Brunswick

Kittery

›

‹

50–100

17

Androscoggin

County

York County

Cumberland

County

Cumberland County

Oxford County

Oxford CO

York County

NE

W HAMPSHIRE

MAINE

Study area

MAINE

EXPLANATION

71° 70°15'

44°

43°15'

Streamflow site and

site number—See table 2

Recurrence interval,

in years

Greater than

Less than

0

0

10 MILES

10 KILOMETERS

<5

10-50

5–10

10–50

50

50

10–50

10–50

50–100

100–500

100–500

500

500

>500

>500

>500

>500

>500 >500

10–50

10–50

10–50

50–100

100–500

Base from U.S. Geological Survey and

Maine Office of Geographic Information System digital files,

North American Datum 83, Universal Transverse Mercator grid, Zone 19

3

62

37

39

60

59

38

51

57

17

61

2

8

58

55

49

42

34

33

28

22

12

16

13

15
16 Flood of April 2007 in Southern Maine

can be expected at a given site on a stream. The curves were 

developed by analyzing thousands of sites with recorded flood 

flows, and then using the sites with the most extreme flows 

to draw the envelope curves for 17 different regions in the 

United States. Maine is in region 1 (region 1 comprises Maine, 

Vermont, most of New Hampshire, most of Connecticut, 

western Massachusetts, and a small part of Rhode Island). The 

peak flows computed for this study plotted a similar distance 

below the Crippen region 1 envelope curve. None of the flood 

flows for the April 2007 flood in southern Maine reached or 

exceeded the potential maximum flood flow as defined by the 

Crippen and Bue (1977) envelope curves. 

Characteristics of the Flood in the 

Mousam River Watershed

The Mousam River watershed (fig. 12) was heavily 

impacted by both the May 2006 flood and the April 2007 

flood, and substantial damage to houses, roads, and culverts 

occurred both years. In addition, peak streamflows at the 

Mousam River near West Kennebunk (USGS station number 

01069500) (table 2) were calculated to have greater than 

100-year recurrence intervals both years. The Mousam River 

watershed was investigated to determine the impact that the 

many small dams and reservoirs in the watershed had during 

the 2007 flood and to determine the potential impact that 

the dams and reservoirs could have during any event of 

this magnitude. 

The analysis below compares the amount of water 

stored behind the dams in the Mousam River watershed to 

the amount of precipitation that fell throughout the watershed 

during the April 2007 flood. In addition, potential current 

storage and total storage available behind each dam prior 

to the April 2007 flood are calculated. Effective storage is 

defined in MEMA dam-inspection reports as storage below 

the spillway elevation that does not include dead storage 

(storage that cannot be released) (T. Fletcher, Maine State 

Dam Inspector, written commun., 2007). Because of the 

lack of comprehensive dam plans with surveyed gate and 

spillway elevations and incomplete water-level records, many 

assumptions were made to conduct this analysis. Without 

knowing the timing of the potential additional runoff and 

without surveying and modeling the dam outlets, the water 

elevations that the stored water could reach downstream of the 

dams cannot be accurately determined. 

The Mousam River watershed has a drainage area of 

117 mi2 at the mouth and includes 13 dams with varying 

capacity to regulate flows and three additional historical 

dams that have been breached or are technically too small to 

be classified as dams (table 3). Thirteen dams control 

1,420 million ft3 of effective storage (T. Fletcher, Maine State 

Dam Inspector, written commun., 2007). Five of the dams 

are on the west branch of the Mousam River in Shapleigh 

and Sanford; one is on the Middle Branch Mousam River in 

Alfred; two are on Littlefield River (the eastern tributary to the 

Mousam River) in Alfred; and five are on the main stem of the 

Mousam River downstream of Estes Lake (fig. 12). Only 3 

of the 13 reservoirs have effective storage capacities over 

100 million ft3—Square Pond, Mousam Lake, and Estes 

Lake—and another 2 have effective storage capacity between 

50 and 100 million ft3—Bunganut Pond, and the Pond above 

Old Falls Dam (table 3). Of these five reservoirs, only 

Square Pond and Mousam Lake are regulated by dams 

designated as flood-control dams in the dam-inspection reports 

(T. Fletcher, Maine State Dam Inspector, written commun., 

2007). Although the remaining dams in the watershed are not 

designated flood-control dams, their design does allow for 

some flood control.

Although the USGS did not operate a continuous streamflow-gaging station in the Mousam River watershed in 2007, 

the USGS collected continuous streamflow-gaging data on the 

Mousam River near West Kennebunk on Whichers Mill Road 

(USGS station number 01069500) from October 1939 

to September 1984. The rating curve for this station was 

assumed to be stable and was used to calculate a peak flow 

of 9,230 ft3/s from documented HWMs near the discontinued 

station in April 2007 (site 3, table 2). In addition, HWMs and 

channel-geometry data were collected on the Mousam River 

at Route 4 near Sanford, Maine, in order to create a hydraulic 

model that was used to estimate a peak streamflow of 

2,400 ft3/s at this site for the April 2007 flood (site 2, table 2). 

A continuous-record streamflow-gaging station was established on the Mousam River at Route 4 (USGS station number 

01068910) in April 2008 and another station was reestablished 

on the Mousam River near West Kennebunk (USGS station 

number 01069500) in November 2008. 

Square Pond

Square Pond has a drainage area of 4.3 mi2, a surface area 

of 1.41 mi2, a normal pool elevation of 523 ft NAVD 88, and 

a total effective storage of 177 million ft3 (table 3). Square 

Pond is located at the headwaters of the main stem of the 

Mousam River in the northwestern portion of the watershed 

in Shapleigh, Maine (fig. 12). Square Pond Dam is at the 

northeast corner of Square Pond and it controls discharge of 

water into a canal. There is a natural outlet at the southwest 

corner of the lake, which is lower in elevation than the crest of 

the Square Pond Dam and is not regulated. 

Square Pond Dam has a single 2- by 2-ft gate with an 

invert that is lower in elevation than the natural outlet, allowing for discharges into the canal. Although surveyed elevations 

were not available for Square Pond Dam, the dam operator 

indicated that the invert of the gate is at least 6 ft below the 

top of a trash-rack grate and at least 10 ft down from the top of 

the dam (M. Blouin, Sanford Dam Operator, personal commun., 2008). There are no flashboards or flood gates as part of 

this structure, although the Square Pond Dam is a designated 

flood-control dam. It is unlikely that water would overtop the 

dam, because water would flow out of the natural outlet before 
Characteristics of the Flood in the Mousam River Watershed 17 Figure 12. Location of dams and U.S. Geological Survey streamflow-gaging stations in the Mousam River watershed, southern Maine. Base from U.S. Geological Survey and Maine Office of Geographic Information System digital files, North American Datum 83, Universal Transverse Mercator grid, Zone 19

Mousam River watershedand boundaryDam or impoundmentStreamflow-gaging station and station number

#

01069500

01069500

01068910

Mill St Dam

Kesslen Dam

River St Dam

Old Falls Dam

Trafton

Bk

Dam

Twine Mill Dam

Square Pond Dam

Emery Mills Dam

Dane Perkins Dam

Bunganuc Pond Dam

Littlefield River Dam

New Dam at Estes Lake

Goodall Sanford Dam

70°30' 71°00'

43°35'43°20'

00

5

5

10 MILES

10 KILOMETERS

EXPLAN

ATION

W NE HAMPSHIRE

MAINE

Wells

Saco

Acton

Lebanon

Sanford

Lyman

Hollis

Waterboro

Berwick

Alfred

Shapleigh

Newfield

Biddeford

Kennebunk

Arundel

North Berwick

Kennebunkport

MAINEStudy area

Middle B ranch

Mousam River

Mousam

River

Mousam

River

Littlefield River
18 Flood of April 2007 in Southern Maine Table 3. Mousam River watershed drainage areas, streamflows, and reservoir storage, southern Maine. [mi2, square miles; ft3/s, cubic feet per second; --, not determined; Rt, route; NA, not applicable; ft3, cubic feet] Drainage areaa (mi2) Surface area of reservoirb (mi2) Total effective storagec (millions of ft3) April 15–18, 2007 Depth of water storedd (ft) Estimated volume of water storede (millions of ft3) Estimated peak outflow (ft3/s) Stored precipi- tation spread over basin (inches) Stored precipitation spread over basin (percent of total precipitation)f Mousam River (West Branch) Square Pond Dam 4.3 1.41 177 2.00 79 -- 7.8 86 Emery Mills Dam at Mousam Lake 29.0 1.57 554 5.00 208 -- 4.3 47 Mill St/Alpaca Dam 37.5 0.06 16 -- -- -- -- -- River St/Stump Pond Dam 38.3 0.10 17 -- -- -- -- -- Godall-Sanford Mill Pond/#1 Pond Dam 42.2 0.16 24 -- -- -- -- --

Mousam River at Rt 4 (01068910) 45.1 NA NA NA NA 2,400 2.7 30

Littlefield River (East Branch of Mousam River)

Bunganut Pond 2.5 0.44 85 -- -- -- -- --Littlefield River/Alfred Mills Dam 22.4 0.04 7 -- -- -- -- --

Middle Branch Mousam River

Trafton Brook Dam 15.0 0.04 8 -- -- -- -- --

Main Stem Mousam River

New Dam at Estes Lake 98.4 0.73 456 0.00 0 9,230 1.3 14Old Falls Dam 102.2 0.13 57 -- -- -- -- --Dane Perkins 106.4 0.04 7 -- -- -- -- --Twine Mill Dam 106.7 0.02 4 -- -- -- -- --Kesslen Dam at Rt 1 111.6 0.04 8 -- -- 10,900 1.1 12

TOTAL STORAGE upstream of Rt 1 dam 1,420 287

a Drainage areas are from GIS analyses conducted for this report and may not match dam-inspection reports.b Surface areas are from dam-inspection reports.c Storage at spillway elevation that does not include dead storage (as defined in Maine Emergency Management Agency Dam Inspection reports).d From dam operator records.e Depth of water stored multiplied by surface area of reservoirs.f Assuming total precipitation from April 15 through 18, 2007 plus snow water equivalent is equal to 9 inches.
Characteristics of the Flood in the Mousam River Watershed 19

overtopping would occur. Square Pond has a large amount of 

effective storage, but very little dam-operator control. 

Dam-operator records indicate that the gate on the 

Square Pond Dam had been fully open since the preceding 

fall (2006), and water levels had been roughly 21 in. below 

the top of the trash-rack grate from January 2007 through the 

beginning of April 2007. With the gate fully open throughout 

this period, the maximum amount of storage was maintained. 

Water levels rose from 20 in. below the grate to 8 in. below the 

grate between April 4 and 16, 2007, and then rose from 8 in. 

below the grate to 4 in. above the grate from April 16 through 

18 (M. Blouin, Sanford Dam Operator, personal commun., 

2008). For the purposes of these analyses, the assumption is 

made that most of this 2-ft rise occurred from April 15 

through 18. Records at the Emery Mills Dam on Mousam 

Lake just downstream of Square Pond support this 

assumption because water levels in Mousam Lake did not 

rise from April 4 through 15, 2007 (see Emery Mills Dam 

at Mousam Lake). Although water did not overtop the dam 

during the April 2007 flood, water was flowing out of the 

natural outlet during this period. Flows and (or) water levels at 

the natural outlet are not recorded by the dam operator. 

On the basis of the estimated 2-ft rise in the reservoir and 

a surface area of 1.41 mi2, Square Pond stored approximately 

79 million ft3 of water during the April 2007 flood. If water 

levels behind the dam could be drawn down to make all 

177 million ft3 of potential effective storage available, a 

100-year inflow event could potentially be stored in Square 

Pond. This may not be possible during wet years with only a 

single 2- by 2-ft gate available to control water levels.

Mousam Lake

The Mousam Lake watershed has a drainage area of 

29 mi2 at Emery Mills Dam and includes Square Pond. 

Mousam Lake has a surface area of 1.57 mi2, a normal 

pool elevation of 478 ft NAVD 88 behind the dam, and a 

potential effective storage at the elevation of the spillway of 

554 million ft3 (table 3). The dam has two 35-inch diameter 

gates and an emergency spillway that is 57 ft wide and has 

a capacity of 2,200 ft3/s. Emery Mills Dam, at the outlet of 

Mousam Lake, is a designated flood-control dam (T. Fletcher, 

Maine State Dam Inspector, written commun., 2007). 

Water behind the Emery Mills Dam was 4 to 5 ft below 

the level of the spillway throughout early April 2007. It rose 

from 4.75 ft below the spillway to 3 in. above the spillway 

between April 15 and 18, 2007 (rain from the Patriots’ Day 

Storm started on April 15). The Emery Mills Dam gates were 

partially open in the days preceding the flood and then were 

fully opened on April 18 during the flood (M. Blouin, Sanford 

Dam Operator, personal commun., 2008). The 5.0 ft rise in 

Mousam Lake during the flood represents a volume of approximately 208 million ft3

 of water with an assumed surface area 

of the lake of 1.57 mi2 (table 3). 

Estes Lake

The Estes Lake watershed has a drainage area of 

98.4 mi2 at New Dam, just downstream of where the Littlefield 

River, and the west and middle branches of the Mousam River 

converge. Estes Lake has a surface area of 0.73 mi2, a normal 

pool elevation of 214 ft NAVD 88 behind the dam, and a 

potential effective storage at the elevation of the spillway of 

456 million ft3 (table 3). New Dam is a hydroelectric project 

dam on the main stem of the Mousam River in Kennebunk, 

Maine, and is located just upstream of the former USGS 

streamflow-gaging site at Whichers Mill Road (station number 

01069500), and thus, flows calculated at Whichers Mill Road 

can be used to represent outflows from New Dam. Although 

the dam has two turbines with a combined hydraulic capacity 

of 320 ft3/s, there are no flood gates, and flashboards are not 

used; thus, there is limited capacity for altering the flow over 

the crest of the dam during times of extreme high flows 

(L. Loon, Ridgewood Power, personal commun., 2008). New 

Dam is not designated as a flood-control dam and even if 

all the effective storage in Estes Lake was available at the 

time of the April 2007 flood, it is unlikely that the timing and 

magnitude of the peak outflow could have been controlled 

appreciably through dam operation. 

Water was flowing over the crest of the dam throughout 

April 2007, indicating that all effective storage was full at the 

time of the Patriots’ Day Storm (L. Loon, Ridgewood Power, 

personal commun., 2008). Although New Dam operators typically have a goal of maintaining water levels 1 ft below the 

dam crest during April, water has spilled over the crest of the 

dam during April in every year from 2004 to 2008. This suggests that the ability to draw this dam down through regulation 

during normal spring periods is minimal. 

Combined Impact of Dams

Approximately 20 percent of total effective storage in the 

Mousam River watershed was available preceding the April 

2007 flood and was used during the event. The storage of 

this water may have attenuated peak flows, especially on the 

west branch of the Mousam River where most of the effective 

storage was available. The estimate of peak streamflow was 

2,400 or 53 ft3/s per square mile in April 2007 on the west 

branch of the Mousam River at Route 4 in Sanford—yet it was 

9,230 or 93 ft3/s per square mile in April 2007 on the main 

stem of the Mousam River at Whichers Mill Road (station 

number 01069500). This suggests that flood runoff was indeed 

stored in the headwaters of the west branch of the Mousam 

River in Square Pond and Mousam Lake.

An estimated 9 in. of rain and snow water equivalent 

fell or melted throughout the Mousam watershed during the 

Patriots’ Day Storm (see section Precipitation Amounts) 

above. Only Square Pond and Mousam Lake had any 

substantial storage available preceding the April 2007 flood 

and stored 79 and 208 million ft3 of water, respectively, for 
20 Flood of April 2007 in Southern Maine

a total of 287 million ft3 of water (table 3). If the 79 million 

ft3 of water stored in Square Pond is spread evenly across the 

whole watershed upstream of Square Pond Dam, it represents 

7.8 of the 9 in. (or 86 percent of the total precipitation) that 

fell or melted upstream of this location. Water stored above 

Emery Mills Dam (287 million ft3 of water in Square Pond 

and Mousam Lake combined) represents 4.3 in. (or 47 percent 

of the 9 in. that fell or melted) if it is spread evenly across 

the watershed upstream of Emery Mills Dam. Although 

when this additional water would have run off had it not been 

stored is unknown—and thus, its resultant increase in flow is 

unknown—this is water that potentially could have added to 

peak streamflows downstream in the watershed. 

No appreciable amount of water was stored in the reservoirs downstream of the Emery Mills Dam during the storm. 

Estimates of the percentage of water stored to water that fell 

(or melted) throughout the remainder of the watershed can be 

obtained by dividing the 287 million ft3 of water stored above 

Emery Mills Dam by the drainage area at each location. If 

the stored water is spread evenly throughout the basin at New 

Dam and at Kesslen Dam at Route 1, the 287 million ft3 of 

water stored represents 1.3 and 1.1 in. of water (or 14 and 

12 percent of the total 9 in.), respectively. 

None of the dams in the Mousam watershed have large 

flood-release gates that would allow for increases of flow during a flood event appreciably above the flow that would occur 

naturally during a high-flow event, once the spillway was 

overtopped. There is a great deal of effective storage in the 

watershed that could potentially be made available preceding 

a large flood event assuming the event could be predicted days 

to weeks in advance, and assuming streamflows preceding the 

event were not so large as to prevent the lowering of reservoir 

levels. Water-resource managers commonly need to balance 

flood control with potentially competing water-use interests such as hydraulic capacity, summer low flows, wildlife 

habitat, and recreation. If all effective storage in the Mousam 

River watershed were made available preceding an event, 

flood flows equivalent to or less than a 100-year event could 

potentially be attenuated. This does not take into account the 

practicality of maintaining large amounts of storage, and as 

noted above for New Dam at Estes Lake, it was not possible 

to maintain any available storage during the month of April in 

any of the 4 years preceding the 2007 event because of consistently high amounts of spring runoff during those years. Even 

where effective storage was not available preceding this event, 

natural or uncontrollable storage (storage above the dam-crest 

elevations) in the reservoirs throughout the Mousam River 

watershed likely attenuated peak flows. 

Historical Floods in Southern Maine

Minimal historical peak-flow data are available for southern Maine, especially York County, because there are so few 

continuously operated streamflow-gaging stations with long 

periods of record. Riverine floods with recurrence intervals 

greater than 50 years occurred in south-central and southwestern Maine in March of 1936 and 1953, respectively (Maloney 

and Bartlett, 1991). More recent floods occurred in southern 

Maine in 1987, 1996, and 2006 (Fontaine and Nielsen, 1994; 

Hodgkins and Stewart, 1997; Stewart and Kempf, 2008). 

Peak streamflows during 2006 and 2007 floods were generally 

greater than those in 1996 or 1987. Northeasters and hurricanes accompanied by high tides can cause coastal flooding 

and erosion in addition to riverine flooding. Major coastal 

flooding of unknown recurrence intervals occurred in southern 

Maine during November in 1945, 1963, and 1968, and during 

February in 1972 and 1978 (Federal Emergency Management 

Agency, 1982–2003). 

Extreme flooding events with recurrence intervals 

greater than 100 years occurred in the springs of 2006 and 

2007 in southern Maine. Both storms were centered in coastal 

York County. Of the nine sites at which estimates of peak 

streamflow were obtained for both floods, flows were greatest 

in 2006 at Merriland River in Kennebunk (site 16, table 2), 

Ogunquit River in Ogunquit (site 13, table 2), Blacksmith 

Brook in Wells (site 15, table 2), Cape Neddick River in 

York (site 12, table 2), and Branch Brook near Kennebunk 

(site 17, table 2). These sites are all located close to 

Kennebunk, Maine, and the coast. Sites somewhat farther 

from the coast such as Little River in Berwick (site 8), Stony 

Brook at East Sebago (site 61, table 2), Saco River at Cornish 

(site 62, table 2), and Mousam River near West Kennebunk 

(site 3, table 2) had higher peak flows in 2007 than in 2006 

(table 4). 

Table 4. April 2007 peak flows in comparison to May 2006 peak 

flows in southern Maine.

[ft3/s, cubic feet per second]

Site 

number Stream and location

2006

Peak flow 

(ft3/s)

2007

Peak flow 

(ft3/s)

3 Mousam River near West

Kennebunk

6,100 9,230

8 Little River, Berwick 3,390 4,640

12 Cape Neddick River, York 2,250 1,010

13 Ogunquit River, Ogunquit 3,110 2,230

15 Blacksmith Brook, Wells 473 260

16 Merriland River, Wells 2,240 1,860

17 Branch Brook near Kennebunk 1,500 1,330

61 Stony Brook at East Sebago 40 125

62 Saco River at Cornish 14,900 17,000
Comparison of the April 2007 Flood Data to Flood Insurance Studies 21

Comparison of the April 2007 Flood 

Data to Flood Insurance Studies

Flood Insurance Studies (FISs) published by FEMA 

provide 10-, 50-, 100-, and 500-year recurrence-interval 

streamflows and water-surface elevations for many flooding 

sources affected by the April 2007 flood in southern Maine. 

In many cases, flood-frequency data calculated for this report 

(table 2) differed from flood-flow-frequency data published in 

the applicable FIS (Federal Emergency Management Agency, 

1982–2003) (table 5). Differences show where updated 

techniques and up to 30 years of additional data can change 

estimated statistical peak flows for selected recurrence intervals. Streamflows and peak water-surface elevations observed 

during the April 2007 flood are presented in table 5 alongside 

streamflows and water-surface elevations from the same locations compiled from the appropriate FIS. This table identifies 

sites at which theoretical FIS water-surface-elevation profiles are not consistent with the peak water-surface elevation 

observed in April 2007, given the peak streamflow observed 

in April 2007. Theoretically, the recurrence interval for the 

peak water-surface elevation and the recurrence interval for 

the peak streamflow from the same event at the same location 

should be the same.

Peak flows with 10-, 50-, 100- and 500-year recurrence 

intervals were calculated for selected locations in southern 

Maine using log-Pearson type-3 frequency analyses where historical streamflow-gaging data were available and regression 

equations where historical data were not available (table 2). 

At 8 of the 15 sites, 100-year recurrence-interval streamflows 

calculated for this project were at least 10 percent smaller than 

those in the current FIS. For Mousam River, Ogunquit River, 

Merriland River, Kennebunk River, Stroudwater River, and 

Crooked River, drainage-area adjustments had to be applied 

to the flows published in the current FIS before they could 

be compared to peak flows calculated for this report (Federal 

Emergency Management Agency, 1982–2003). FIS profiles 

were adjusted from NGVD 29 to NAVD 88 at all sites in order 

to make the comparison with 2007 peak elevations surveyed 

in NAVD 88. 

If flow frequencies were computed with log-Pearson 

type-3 frequency analyses for both this work and the current 

FIS, differences could be the result of the length of record 

used in the analyses. For example, 30 years of additional data 

now available at Saco River at Cornish (USGS station number 

01066000) resulted in 50-, 100-, and 500-year flows calculated 

for this report (table 2) that were at least 10 percent smaller 

than the 50-, 100-, and 500-year flows in the current FIS at 

this location (table 5). At Ossipee River at Cornish (USGS station number 01065500), the 500-year flow calculated for this 

report (table 2) was 12 percent less than the 500-year flow in 

the current FIS (table 5). 

FISs typically have flow frequencies calculated with 

an older set of equations (Morrill, 1975). Updated equations 

(Hodgkins, 1999) developed with an additional 25 years of 

data and improved statistical techniques were used to calculate 

flow frequencies for this project. Blacksmith Brook in Wells 

(site 15, fig. 2) and Merriland River in Wells (site 16, fig. 2), 

both had streamflows at all recurrence intervals calculated 

with new regression equations (Hodgkins, 1999) that were at 

least 50 percent smaller than flows in the current FIS calculated with the older regression equations (Morrill, 1975) 

(table 5). An improved drainage-area calculation at Blacksmith 

Brook could have been part of the reason for the large change. 

Peak flows for the 100-year recurrence intervals at Ogunquit 

River in Ogunquit (site 13, fig. 2) and Cape Neddick River in 

York (site 12, fig. 2) calculated with the newer equations by 

Hodgkins (1999) were 31 and 21 percent less than the 

100-year recurrence interval peak flows in the FISs calculated 

with the equations developed by Morrill (1975). 

For many current FISs, the Natural Resources Conservation Service (NRCS) TR-20 theoretical rainfall-runoff method 

(Pilgrim and Cordery, 1993) was used to generate flowfrequency data. Flows for the 100-year recurrence interval 

calculated with the equations developed by Hodgkins (1999) 

at the Great Works River Dam at Route 9 (site 28, fig. 2) were 

24 percent less than the 100-year recurrence-interval flow in 

the FIS calculated with the NRCS TR-20 model. 

Estimates for flows of selected recurrence intervals 

at the Little Ossipee River near South Limington (USGS 

station number 01066500, site 37, fig. 2) and the Mousam 

River near Kennebunk (USGS station number 01069500, 

site 3, fig. 2) were calculated using a traditional log-Pearson 

type-3 frequency analysis and an NRCS TR-20 model for the 

respective FISs. Flow-frequency data at both of these stations 

were updated by use of the Expected Moments Algorithm 

(EMA) developed by Cohn and others (1997) and analyses in 

Hodgkins and others (2007) in order to better accommodate 

historical peak-flow data outside the period of record. The 

100-year flow at the Little Ossipee River was 10 percent less 

and the estimate of the 100-year flow at the Mousam River 

was 85 percent greater using the EMA.

At Mousam River at Sanford (site 2, fig. 2), Little 

Ossipee River near South Limington (site 37, fig. 2), Royal 

River at Yarmouth (site 39, fig. 2), Blacksmith Brook at Wells 

(site 15, fig. 2), and Ogunquit River in Ogunquit (site 13, 

fig. 2), the observed water-surface elevations (determined 

from HWMs) from the April 2007 flood were bracketed 

by elevation profiles with higher than expected recurrence 

intervals given the observed peak streamflows and modeled 

elevations in the FIS. The computed water-surface elevations 

from the April 2007 flood at the Great Works River Dam in 

North Berwick (site 28, fig. 2) were bracketed by elevation 

profiles with the same recurrence intervals as would be 

expected given observed peak streamflows and modeled 

elevations. At the Stroudwater River Dam in Portland 

(site 42, fig. 2), the Merriland River in Wells (site 16, 

fig. 2), the Kennebunk River in Kennebunk (site 22, fig. 2), 

and Collyer Brook at Gray (site 38, fig. 2), observed watersurface elevations were bracketed by elevation profiles with 

the same recurrence interval as would be expected given 
22 Flood of April 2007 in Southern Maine Table 5. Relation of computed April 2007 flood discharges and high-water mark elevations to flood-insurance study data for selected locations in southern Maine. [ft3/s, cubic feet per second; FIS, flood-insurance study; yr, year; HWM, high-water mark; ft, feet; US, upstream; RE, right edge of water (when facing downstream); --, not determined; DS, downstream; LE, left edge of water. All elevations are relative to North American Vertical Datum of 1988 (FIS profile elevations were originally relative to National Geodetic Vertical Datum of 1929, but were adjusted for this report); All HWMs listed are approximately one structure-width upstream or downstream of the listed location. Flow frequencies in bold have values computed for this report in table 2 that are greater than 10 percent different than the values in the current FIS compiled in this table. Stations in italics have peak discharges observed during the April 2007 flood that are bracketed by different recurrence intervals than the recurrence intervals that bracket the observed peak water-surface elevation in April 2007.] Site num- ber Water body and location 2007 Peak flow (ft3/s) Flow frequency discharge from FIS (ft3/s) HWM number 2007 HWM location Elevation (ft) Elevations from FIS profiles (ft) 10-yr 50-yr 100-yr 500-yr Method 10-yr 50-yr 100-yr 500-yr 2 Mousam River, Sanforda 2,400 1,320 1,940 2,250 3,040 TR-20b 3 US RE 238.5 235.0 236.4 237.0 238.4 3 Mousam River near West Kennebunka 9,230 -- -- 3,910 -- TR-20b 7–9c US RE 172.5 -- -- 167.3 -- 12 Cape Neddick River, York 1,010 479 785 950 1,420 Morrilld 36 US RE 21.5 17.3 18.5 19.0 20.1 35 DS LE 18.3 17.3 18.3 18.9 20.0

13 Ogunquit River, Ogunquita 2,230 802 1,330 1,620 2,450 Morrilld 37 US RE 90.4 82.7 84.5 85.5 88.3

38 DS LE 89.4 82.3 84.3 85.3 87.9

15 Blacksmith Brook, Wells 260 179 312 385 607 Morrilld 41 US LE 44.1 41.1 42.0 42.4 43.5

43 DS LE 41.2 40.7 41.6 42.0 43.0

16 Merriland River, Wellsa 1,860 873 1,430 1,730 2,590 Morrilld 46, 47c US RE 24.1 19.2 21.4 22.6 24.8

44, 45c DS RE 23.4 19.1 21.4 22.6 24.8

22 Kennebunk River, Kennebunka 5,730 1,950 3,080 3,670 5,330 Morrilld 59 US RE 44.9 41.2 43.2 43.8 44.5

58 DS RE 42.9 34.5 35.6 36.3 37.3

28 Great Works River Dam, North Berwick 2,780 1,070 2,000 2,360 3,930 TR-20b 71 US LE 125.1 123.3 124.5 125.1 126.337 Little Ossipee River near South Limington 8,220 4,250 7,240 8,850 13,600 LP3e 91 US RE 284.2 280.4 282.9 284.3 287.4

92 DS LE 280.9 278.6 279.8 280.5 282.4

38 Collyer Brook near Gray 1,450 870 1,480 1,750 2,530 TR-20b 97 US LE 185.8 184.4 186.7 187.6 190.2

94, 95c DS RE 182.3 182.0 182.9 183.3 184.2

39 Royal River at Yarmouth 8,160 6,090 9,060 10,500 14,500 LP3e 99–101c US RE 16.7 8.6 11.8 13.3 16.642 Stroudwater River Dam, Portlanda 2,780 1,910 3,130 3,780 5,220 TR-20b 108 US RE 23.3 22.6 23.8 24.3 25.2

49 Crooked River, Naplesa 6,150 5,380 8,410 9,750 13,200 TR-20b 122–124c US LE 289.9 296.0 299.9 300.8 302.6

125 DS RE 288.9 291.3 295.2 296.3 298.7

51 Ossipee River at Cornish 9,600 7,840 11,800 13,700 18,900 LP3e 137 US RE 286.9 282.9 285.0 285.8 287.4

133 DS LE 286.8 282.9 285.0 285.8 287.4

62 Saco River at Cornish 17,000 23,100 33,800 39,000 52,600 LP3e 160 at gage 274.1 275.8 279.4 281.0 285.3

aDrainage area adjustments made to flow frequency discharges to match locations of 2007 peak flows and elevations.bNatural Resources Conservation Service hydrologic evaluation model.cAverage of points.dMorrill (1975).eLog-Pearson type-3 frequency analysis.
Summary and Conclusions 23

observed peak streamflows and modeled elevations in the 

FIS. However, models at Collyer Brook and at Merriland 

River showed less hydraulic drop through the bridges than 

was observed, and the FIS hydraulic model for Kennebunk 

showed a hydraulic drop greater than 7 ft through the bridge 

than was observed during the April 2007 flood. Cape Neddick 

at York had a higher upstream peak elevation and a lower 

downstream peak elevation than was expected because the FIS 

hydraulic model showed almost no drop through the bridge, 

but the elevations observed in April 2007 showed a 3.2-ft 

drop through the bridge. Crooked River at Naples had watersurface elevations upstream and downstream of the bridge that 

were bracketed by recurrence intervals lower than would be 

expected given observed peak streamflows and water-surface 

elevations modeled in the FIS. 

Discrepancies between elevations in the FIS models and 

elevations observed in April 2007 given a known observed 

flow have several possible causes. Discrepancies could be 

caused by the possible geomorphic or structural changes that 

may have taken place at the structure between the FIS analysis 

and the April 2007 flood. Another possible cause of elevation 

discrepancies is the error in determining the elevation from a 

profile plot in the FIS. Choosing the correct location and reading the correct elevation off the profile plot has error associated with it because of the linear interpolation used to develop 

the profiles between surveyed cross sections and because of 

the plot scale. The amount of the error is dependent on the 

rate of change of the profile plot near the structure of interest. There is also error in determining field estimations of the 

HWM elevation, which can be estimated from a single HWM 

or the average of up to three different HWMs. In addition, 

hydraulic models from which elevations are obtained may not 

have been calibrated if there had not been a flood of that magnitude at that location during the period of record and prior 

to the current FIS. Data collected during and after the floods 

in 2006 and 2007 will allow for more accurate calibration of 

future hydraulic models. 

Summary and Conclusions

The Patriots’ Day Storm affected much of the northeastern United States from April 15 through 18, 2007. This 

report focuses on its impact in southern Maine. The storm was 

characterized by up to 8.5 in. of rain falling on top of a wet 

snowpack with up to 1 in. of additional water equivalent—

causing waterways with fairly normal antecedent streamflow 

conditions to overtop their banks. The highest rainfall totals 

in Maine were in coastal York County. Streams in the western 

mountains of York and Cumberland Counties generally had 

peak streamflows with lower recurrence intervals than did 

streams closer to the coast.

Peak-streamflow recurrence intervals were determined at 

24 locations and peak water-surface elevations at 63 locations 

following the April 2007 flood. Peak streamflows were 

determined with data from continuous-record streamflowgaging stations where available, and through hydraulic models 

where stations were not available. The flood resulted in peak 

streamflows with recurrence intervals greater than 100 years 

throughout most of York County, and recurrence intervals 

up to 50 years in Cumberland County. Peak flows at select 

recurrence intervals updated as a part of this study varied 

from less than 10 percent to greater than 100 percent different 

than those that would be expected from the current Federal 

Emergency Management Agency flood-insurance studies. 

This was the second storm in 2 consecutive years to 

have streamflows with recurrence intervals greater than 

100 years on many streams in York County. The April 2007 

flood covered a greater geographical area in Maine than did 

the flood of May 2006—extending into Cumberland County 

in some locations. It is possible to get storms 2 years in a row 

with large recurrence intervals; however, recurrence intervals 

greater than 100 years have a large amount of uncertainty 

associated with them, especially when the period of record at a 

site is short. As more data are collected and assumptions about 

the stationarity of flow frequencies are tested, estimated recurrence intervals may become more accurate. 

The Mousam River watershed was one of the watersheds 

in southern Maine where recurrence intervals of streamflows 

were greater than 100 years in both May 2006 and April 2007. 

Initial calculations in the Mousam River watershed contain many assumptions because field surveying of the dams 

was not included as a part of these flood-routing analyses. 

Although limited storage was available on the west branch of 

the Mousam River preceding the April 2007 flood, many of 

the storage reservoirs on the main stem of the Mousam River 

were filled to capacity and had little effective storage available. Thirty percent of the total precipitation upstream of the 

Mousam River at Route 4 was stored, but only 14 percent of 

total precipitation upstream of New Dam at the outlet of Estes 

Lake was stored. 

A major flooding event such as that of April 2007 

provided an opportunity to compare current Flood Insurance 

Studies (FISs) to actual peak flows and water-surface elevations observed in the field. At 8 of the 15 locations where 

detailed FISs were available, streamflows with 100-year 

recurrence intervals calculated for this report were at least 

10 percent smaller than those in the current (2008) FIS, and 

at 2 of the 15 locations, flows were over 60 percent smaller 

because of additional data or newer regression equations. 

At 2 of the 15 locations (both on the Mousam River), peak 

flows with 100-year recurrence intervals were more than 

10 percent higher than those in the current FIS as a result of 

new methods. 

In many cases, current FIS models had not been calibrated to an actual flood and had peak water-surface elevations with different recurrence intervals than those of the peak 

streamflows measured during the April 2007 flood. Surveyed 

elevations and flows calculated after the 2007 event allowed 

for an independent check of the hydraulic models in the 

current FISs. Observed water-surface elevations determined 
24 Flood of April 2007 in Southern Maine

from high-water marks resulting from the April 2007 flood 

were bracketed by elevation profiles with the same recurrence 

intervals as the recurrence intervals bracketing the observed 

peak streamflows at seven sites, with higher elevation-profile 

recurrence intervals than streamflow recurrence intervals at 

six sites, and with lower elevation-profile recurrence intervals 

than streamflow recurrence intervals at one site. Elevations 

and flows documented in this report can be used to calibrate 

future hydraulic models. 

Acknowledgments

The author would like to thank Thomas Hawley from the 

National Weather Service (NWS) for providing meteorological 

data for this report and Tony Fletcher from the Maine 

Emergency Management Agency (MEMA) for providing 

information regarding the Mousam River dams. The following 

USGS employees provided substantial help by collecting the 

field data for this report: Joshua P. Kempf, Laura E. Flight, 

Lance H. Chapman, and Garrett E. Luszczki. 

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.

Cohn, T.A., Lane, W.L., and Baier, W.G., 1997, An algorithm 

for computing moments-based flood quantile estimates 

when historical flood information is available: Water 

Resources Research, v. 33, no. 9, p. 2089–2096.

Crippen, J.R., and Bue, C.D., 1977, Maximum floodflows in 

the conterminous United States: U.S. Geological Survey 

Water-Supply Paper 1887, 52 p.

Federal Emergency Management Agency, 1982–2003, Flood 

Insurance Studies, Towns of Cornish, Gray, Kennebunk, 

Naples, North Berwick, Ogunquit, Portland, Sanford, South 

Berwick, South Limington, Wells, Yarmouth, York, York 

County, Maine: Washington D.C., variously paged.

Flynn, R.H., 2008, Flood of April 2007 in New Hampshire: 

U.S. Geological Survey Scientific Investigations Report 

2008–5120, 53 p.

Fontaine, R.A., and Nielsen, J.P., 1994, Flood of April 1987 in 

Maine: U.S. Geological Survey Water-Supply Paper 2424, 

50 p.

Hodgkins, G.A., 1999, Estimating the magnitude of peak 

flows in Maine for selected recurrence intervals: U.S. 

Geological Survey Water-Resources Investigations Report 

99–4008, 45 p.

Hodgkins, G.A., and Stewart, G.J., 1997, Flood of October 

1996 in southern Maine: U.S. Geological Survey WaterResources Investigations Report 97–4189, 28 p.

Hodgkins, G.A., Stewart, G.J., Cohn, T.A., and Dudley, R.W., 

2007, Estimated magnitudes and recurrence intervals of 

peak flows on the Mousam and Little Ossipee Rivers for the 

Flood of April 2007 in southern Maine: U.S. Geological 

Survey Open-File Report 2007–1146, 13 p.

Interagency Advisory Committee on Water Data, 1982, 

Guidelines for determining flood flow frequency: Water 

Resources Council Bulletin 17B, 28 p.

Jensenius, J., Hawley, T., Turner, M., and Sturey, A., 2007, 

Coastal Storm April 15–23, 2007 (preliminary report), 

National Weather Service, Gray, Maine, April 27, 2007, 

80 p.

Maine Cooperative Snow Survey, 2007, accessed August 1, 

2007, at http://www.maine.gov/rfac/rfac_snow.shtml/.

Maloney, T.J., and Bartlett, W.P., Jr., 1991, Maine floods and 

droughts, in Paulson, R.W., Chase, E.B., Robert, R.S., and 

Moody, D.W. (compilers), 1991, National water summary 

1988–99—Hydrologic events and floods and droughts: 

U.S. Geological Survey Water-Supply Paper 2375, 

p. 311–318.

Matthai, H.F., 1967, Measurement of peak discharge at width 

contractions by indirect methods: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 3, 

chap. A4, 44 p.

Morrill, R.A., 1975, A technique for estimating the magnitude 

and frequency of floods in Maine: U.S. Geological Survey 

Open-File Report 75–292, 44 p.

National Oceanic and Atmospheric Administration, 2002, 

Climatography of the United States No. 81, monthly station 

normals of temperature, precipitation, and heating and cooling degree days, 1971–2000: Region 17, Maine, 16 p.

National Weather Service, 2008, Gray/Portland: accessed 

May 21, 2008, at http://www.weather.gov/climate/local_

data.php?wfo=gyx

Pilgrim, D.H., and Cordery, I., 1993, Flood runoff, in

Maidment, D.R., ed., Handbook of Hydrology: New York, 

McGraw-Hill Inc., p. 9.1–9.42.
References Cited 25

Rantz, S.E., and others, 1982, Measurement and computation 

of streamflow: U.S. Geological Survey Water-Supply Paper 

2175, v. 2, 631 p. 

Stewart, G.J., and Kempf, J.P., 2008, Flood of May 2006 in 

York County, Maine: U.S. Geological Survey Scientific 

Investigations Report 2008–5047, 19 p.

U.S. Army Corps of Engineers, 2004, HEC-RAS River Analysis System Version 3.1.2: Hydrologic Engineering Center, 

accessed September 19, 2006, at http://www.hec.usace.

army.mil/.

U.S. Geological Survey, 2008, National Water Information 

System: accessed May 21, 2008, at http://waterdata.usgs.

gov/me/nwis/sw

Wilks, D.S., and Cember, R.P., 1993, Atlas of precipitation 

extremes for the northeastern United States and southeastern Canada: Cornell University, Northeast Regional 

Climate Center, 40 p.
26 Flood of April 2007 in Southern Maine

Table 1. Peak water-surface elevations for April 2007 flood in York and Cumberland Counties, Maine.—Continued

[HWM, high-water mark; Northings and Eastings referenced to Maine State Plane West, in feet relative to North American Datum of 1983; elevations, in feet, 

referenced to North American Vertical Datum of 1988; Rt., route; DS, downstream; LE, left edge of water (when facing downstream); US, upstream; RE, right 

edge of water; Rd., Road; St., Street; Ln., Lane; RR, railroad; Br., bridge; E Br, East Branch; site number, location shown on figure 2]

Site

number

HWM 

number

Easting

(feet)

Northing

(feet)

Elevation

(feet) Water body Location and description

1 1 2777709.5 238615.3 426.10 Mousam River Emery’s Mills/Rt. 11/109, DS LE

1 2 2777635.6 238610.8 426.34 Mousam River Emery’s Mills/Rt. 11/109, US LE

2 3 2800776.0 213744.0 238.47 Mousam River Rt. 4, US RE

2 4 2800876.8 213829.0 238.37 Mousam River Rt. 4, US LE1

2 5 2800902.0 213868.4 238.51 Mousam River Rt. 4, US LE2

2 6 2801016.8 213731.4 235.57 Mousam River Rt. 4, DS LE

3 7 2822128.8 213453.7 172.52 Mousam River Whichers Mill Rd., US RE1

3 8 2822133.1 213451.7 172.45 Mousam River Whichers Mill Rd., US RE2

3 9 2822159.7 213445.0 172.52 Mousam River Whichers Mill Rd., US RE3

4 10 2841465.4 208168.0 87.96 Mousam River Mill St./Thompson St., DS LE1

4 11 2841479.2 208170.5 88.13 Mousam River Mill St./Thompson St., DS LE2

4 12 2841250.4 208291.6 89.02 Mousam River Mill St./Thompson St., US LE

5 13 2849520.4 204844.4 49.92 Mousam River Intervale Rd., US LE 1

5 14 2849528.3 204854.4 49.86 Mousam River Intervale Rd., US LE 2

5 15 2849590.0 204826.3 49.91 Mousam River Intervale Rd., US LE 3

5 16 2849839.3 204784.5 49.64 Mousam River Intervale Rd., US LE 4

5 17 2849844.4 204783.6 49.57 Mousam River Intervale Rd., US LE 5

6 18 2851279.6 203281.8 47.58 Mousam River Partridge Ln., US LE 1

6 19 2851294.2 203244.4 47.56 Mousam River Partridge Ln., US LE 2

7 20 2852757.9 201312.0 39.30 Mousam River Rt. 1, Top of Dam

7 21 2852662.8 201290.8 46.13 Mousam River Rt. 1, US RE1

7 22 2852670.9 201314.2 46.12 Mousam River Rt. 1, US RE2

8 23 2767009.5 177573.9 233.17 Little River Long Swamp Rd., US LE

8 24 2766899.4 177558.6 231.07 Little River Long Swamp Rd., DS LE

8 25 2766919.0 177650.5 230.73 Little River Long Swamp Rd., DS RE

9 26 2762845.3 175526.1 197.37 Little River Ridlon Rd., US RE

9 27 2762765.2 175465.2 196.42 Little River Ridlon Rd., DS RE

10 28 2758042.6 172457.9 187.19 Little River Hubbard Rd., DS RE1

10 29 2758042.6 172457.9 187.21 Little River Hubbard Rd., DS RE2

10 30 2757953.1 172421.6 187.23 Little River Hubbard Rd., DS RE3

10 31 2757947.1 172416.9 187.12 Little River Hubbard Rd., DS RE4

11 32 2760177.4 182225.6 210.08 Keay Brook Ridlon Rd., US RE

11 33 2760215.9 182014.4 204.31 Keay Brook Ridlon Rd., DS LE1

11 34 2760190.7 182089.8 203.72 Keay Brook Ridlon Rd., DS LE2

12 35 2831932.4 131286.3 18.31 Cape Neddick River Rt. 1, DS LE

12 36 2831875.9 131198.6 21.50 Cape Neddick River Rt. 1, US RE

13 37 2829182.4 157694.3 90.43 Ogunquit River North Village Rd., US RE

13 38 2829337.6 157639.3 89.36 Ogunquit River North Village Rd., DS LE

14 39 2837991.9 159806.6 32.51 Ogunquit River Rt. 1, DS LE

14 40 2837843.9 159818.1 40.27 Ogunquit River Rt. 1, US RE

15 41 2845139.6 182424.8 44.10 Blacksmith Brook Rt. 1, US LE

15 43 2845258.8 182362.6 41.23 Blacksmith Brook Rt. 1, DS LE
Table 1 27

Table 1. Peak water-surface elevations for April 2007 flood in York and Cumberland Counties, Maine.—Continued

[HWM, high-water mark; Northings and Eastings referenced to Maine State Plane West, in feet relative to North American Datum of 1983; elevations, in feet, 

referenced to North American Vertical Datum of 1988; Rt., route; DS, downstream; LE, left edge of water (when facing downstream); US, upstream; RE, right 

edge of water; Rd., Road; St., Street; Ln., Lane; RR, railroad; Br., bridge; E Br, East Branch; site number, location shown on figure 2]

Site

number

HWM 

number

Easting

(feet)

Northing

(feet)

Elevation

(feet) Water body Location and description

16 44 2847370.8 186299.2 23.39 Merriland River RR Br US from Rt. 1, DS RE1

16 45 2847407.4 186282.3 23.50 Merriland River RR Br US from Rt. 1, DS RE2

16 46 2847265.3 186375.3 24.11 Merriland River RR Br US from Rt. 1, US RE1

16 47 2847278.7 186372.1 24.09 Merriland River RR Br US from Rt. 1, US RE2

17 48 2841932.6 199288.0 52.48 Branch Brook Rt. 9a, US RE

18 49 2857289.8 264071.8 76.46 Stackpole Brook Simpson Rd., US RE

18 50 2857251.1 264031.9 63.72 Stackpole Brook Simpson Rd., DS RE

19 51 2835988.6 227721.0 143.46 Kennebunk River Dam above Rt. 35, US RE1

19 52 2835991.3 227763.9 142.68 Kennebunk River Dam above Rt. 35, US RE2

19 53 2835989.7 227731.8 142.77 Kennebunk River Dam above Rt. 35, US RE3

20 54 2836244.3 227871.3 125.30 Kennebunk River Rt. 35, DS LE

20 55 2836160.6 227768.7 133.13 Kennebunk River Rt. 35, US RE1

21 56 2850061.2 218542.0 70.33 Kennebunk River Downing Rd., US LE

21 57 2850095.2 218447.7 70.70 Kennebunk River Downing Rd., DS LE1

22 58 2857176.4 207683.9 42.88 Kennebunk River Rt. 1, DS RE

22 59 2857107.2 207786.7 44.92 Kennebunk River Rt. 1, US RE

23 60 2792149.2 212320.3 229.40 Great Works River Old Mill Rd., DS LE

23 61 2792138.8 212401.5 233.36 Great Works River Old Mill Rd., US LE

24 62 2795265.4 203635.1 220.20 Great Works River Sand Pond Rd., DS LE

24 63 2795216.1 203717.6 223.82 Great Works River Sand Pond Rd., US LE

25 64 2799524.3 186930.9 188.11 Great Works River Ford Quint Rd., US LE

25 65 2799481.7 186968.2 188.57 Great Works River Ford Quint Rd., US RE

25 66 2799427.5 186933.4 187.00 Great Works River Ford Quint Rd., DS RE

26 67 2797213.4 182553.0 178.36 Great Works River Oak Woods Rd., US RE

26 68 2797185.4 182436.9 175.44 Great Works River Oak Woods Rd., DS RE

27 69 2800512.2 176994.3 129.45 Great Works River Rt. 4, DS LE

27 70 2800370.4 177057.4 131.58 Great Works River Rt. 4, US LE

28 71 2800865.6 172981.7 125.14 Great Works River Dam off Canal St. above Rt. 9, US LE

29 72 2803304.3 151303.7 94.55 Great Works River Hoopers Sands Rd.-Emerys Br., DS RE

29 73 2803405.7 151236.1 97.30 Great Works River Hoopers Sands Rd.-Emerys Br., US LE

30 74 2800913.5 171108.5 113.09 Great Works River Madison St., DS LE1

30 75 2800786.8 171051.0 112.96 Great Works River Madison St., DS LE2

31 76 2786140.1 140056.7 83.80 Great Works River Rt. 236., DS LE

31 77 2786233.9 140094.7 84.97 Great Works River Rt. 236., US LE

32 78 2784909.2 141101.7 82.38 Great Works River Brattle St. Dam, US RE

32 79 2784848.3 141156.0 82.06 Great Works River Brattle St. Dam, DS RE

33 80 2771946.6 257997.9 559.98 Pump Box Brook Rt. 11, US LE

33 81 2771879.8 258044.1 555.50 Pump Box Brook Rt. 11, DS LE1

33 82 2771871.0 258049.4 554.94 Pump Box Brook Rt. 11, DS LE2

34 83 2762605.9 281713.5 472.30 Little Ossipee River Rt. 11, DS LE

34 84 2762430.9 281752.0 479.64 Little Ossipee River Rt. 11, US RE1

34 85 2762354.7 281750.4 485.95 Little Ossipee River Rt. 11, US RE2
28 Flood of April 2007 in Southern Maine

Table 1. Peak water-surface elevations for April 2007 flood in York and Cumberland Counties, Maine.—Continued

[HWM, high-water mark; Northings and Eastings referenced to Maine State Plane West, in feet relative to North American Datum of 1983; elevations, in feet, 

referenced to North American Vertical Datum of 1988; Rt., route; DS, downstream; LE, left edge of water (when facing downstream); US, upstream; RE, right 

edge of water; Rd., Road; St., Street; Ln., Lane; RR, railroad; Br., bridge; E Br, East Branch; site number, location shown on figure 2]

Site

number

HWM 

number

Easting

(feet)

Northing

(feet)

Elevation

(feet) Water body Location and description

35 86 2772624.7 297439.1 381.80 Little Ossipee River Bridge St., DS RE1

35 87 2772646.8 297444.7 381.50 Little Ossipee River Bridge St., DS RE2

35 88 2772570.5 297413.4 384.27 Little Ossipee River Bridge St., US RE

36 89 2795457.3 299389.5 316.38 Little Ossipee River Rt. 5, US LE

36 90 2795595.6 299339.5 316.38 Little Ossipee River Rt. 5, DS LE

37 91 2819591.2 312426.4 284.17 Little Ossipee River Sand Pond Rd., US RE

37 92 2819371.0 312388.0 280.91 Little Ossipee River Sand Pond Rd., DS LE

38 93 2913214.7 395360.5 181.85 Collyer Brook Rt. 202, DS RE1

38 94 2913229.0 395356.0 181.24 Collyer Brook Rt. 202, DS RE2

38 95 2913186.7 395401.5 183.25 Collyer Brook Rt. 202, DS RE3

38 96 2913228.9 395440.4 181.34 Collyer Brook Rt. 202, DS LE

38 97 2913113.4 395508.0 185.56 Collyer Brook Rt. 202, US LE

38 98 2913088.0 395458.7 186.06 Collyer Brook Rt. 202, US RE

39 99 2949539.8 351984.5 16.67 Royal River Yarmouth, US RE1

39 100 2949542.0 351983.7 16.55 Royal River Yarmouth, US RE2

39 101 2949537.0 351979.6 16.76 Royal River Yarmouth, US RE3

40 102 2930171.7 342925.9 42.54 E Br Piscataquis River Rt. 9, DS LE

40 103 2930070.9 342859.3 42.80 E Br Piscataquis River Rt. 9, DS RE

40 104 2930215.8 342942.0 43.59 E Br Piscataquis River Rt. 9, US LE

40 105 2930194.9 342992.4 43.72 E Br Piscataquis River Rt. 9, US RE

41 106 2919250.9 329761.3 34.34 Piscataquis River Leighton Rd., US LE

41 107 2919201.3 329655.5 33.23 Piscataquis River Leighton Rd., DS RE

42 108 2914582.0 300009.1 23.29 Stroudwater River Dam above Westbrook St., US RE

43 109 2913643.6 300350.7 25.35 Stroudwater River Congress St., US RE

43 110 2913828.8 300220.5 24.64 Stroudwater River Congress St., DS RE

44 111 2908651.6 294653.3 39.27 Long Creek Maine Mall Rd., DS RE

44 112 2908541.0 294804.5 42.30 Long Creek Maine Mall Rd., US RE

45 113 2932033.0 275801.5 7.41 Spurwink River Spurwink Rd., US LE

45 114 2932022.2 275832.9 7.32 Spurwink River Spurwink Rd., US RE

45 115 2932022.4 275839.2 7.33 Spurwink River Spurwink Rd., US RE

45 116 2931920.5 275674.7 6.50 Spurwink River Spurwink Rd., DS LE

46 117 2883697.0 287367.7 38.79 Nonesuch River Mitchell Hill Rd., DS LE

47 118 2906547.5 284595.5 17.21 Nonesuch River Rt. 114, DS LE

48 119 2910487.3 272125.4 7.41 Nonesuch River Blackpoint Rd., DS LE

48 120 2910536.7 272146.1 7.56 Nonesuch River Blackpoint Rd., US LE1

48 121 2910506.4 272158.7 7.40 Nonesuch River Blackpoint Rd., US LE2

49 122 2846112.1 424970.0 289.98 Crooked River Edes Falls Rd., US LE1

49 123 2846103.8 424946.2 289.90 Crooked River Edes Falls Rd., US LE2

49 124 2846110.5 424907.2 289.94 Crooked River Edes Falls Rd., US LE3
Table 1 29

Table 1. Peak water-surface elevations for April 2007 flood in York and Cumberland Counties, Maine.—Continued

[HWM, high-water mark; Northings and Eastings referenced to Maine State Plane West, in feet relative to North American Datum of 1983; elevations, in feet, 

referenced to North American Vertical Datum of 1988; Rt., route; DS, downstream; LE, left edge of water (when facing downstream); US, upstream; RE, right 

edge of water; Rd., Road; St., Street; Ln., Lane; RR, railroad; Br., bridge; E Br, East Branch; site number, location shown on figure 2]

Site

number

HWM 

number

Easting

(feet)

Northing

(feet)

Elevation

(feet) Water body Location and description

49 125 2846142.3 424787.9 288.95 Crooked River Edes Falls Rd., DS LE1

49 126 2846177.8 424766.6 288.67 Crooked River Edes Falls Rd., DS LE2

49 127 2846002.6 424735.0 288.90 Crooked River Edes Falls Rd., DS RE

50 128 2848198.8 417923.6 283.08 Crooked River Rt. 11, US RE

50 129 2848331.4 418021.9 283.48 Crooked River Rt. 11, US LE

50 130 2848357.8 417940.4 283.23 Crooked River Rt. 11, DS LE

50 131 2848318.2 417778.9 283.02 Crooked River Rt. 11, DS RE1

50 132 2848283.9 417710.7 282.73 Crooked River Rt. 11, DS RE2

51 133 2786002.3 355386.1 286.81 Ossipee River River Rd., DS LE1

51 134 2785999.7 355335.2 286.58 Ossipee River River Rd., DS LE2

51 135 2785934.6 355420.3 285.77 Ossipee River River Rd., DS LE3

51 136 2785904.3 355596.0 287.21 Ossipee River River Rd., US LE

51 137 2785786.6 355208.8 286.91 Ossipee River River Rd., US RE

51 138 2785907.0 355153.1 286.74 Ossipee River River Rd., DS RE

52 139 2794615.6 348347.8 327.25 Pease Brook Rt. 25, US RE1

52 140 2794552.7 348369.9 327.47 Pease Brook Rt. 25, US LE1

52 141 2794537.0 348367.4 327.51 Pease Brook Rt. 25, US LE2

52 142 2794540.8 348330.6 327.36 Pease Brook Rt. 25, US LE3

52 143 2794667.5 348432.3 321.68 Pease Brook Rt. 25, DS LE2

53 144 2884574.6 323620.6 84.00 Little River Rt. 202, US RE

53 145 2884763.8 323526.2 83.66 Little River Rt. 202, DS RE

54 146 2887332.4 320867.4 81.80 Little River Rt. 237, US RE

54 147 2887356.7 320867.1 81.69 Little River Rt. 237, US RE

55 148 2885556.2 347553.1 163.37 Pleasant River Pope Rd., US RE1

55 149 2885606.8 347569.8 163.37 Pleasant River Pope Rd., US RE2

55 150 2885479.1 347448.3 160.84 Pleasant River Pope Rd., DS LE

56 151 2834138.2 124573.7 9.28 Briley Stream Bay St., HWM1

56 152 2834111.0 124629.7 9.35 Briley Stream Bay St., HWM2

57 153 2889894.8 257501.8 40.30 Mill Brook Rt. 98, DS LE

57 154 2889793.3 257481.9 43.90 Mill Brook Rt. 98, US LE

58 155 2805301.1 261125.7 259.82 Carl Branch Brook Straw Mill Rd., DS RE

58 156 2805363.8 261235.0 262.66 Carl Branch Brook Straw Mill Rd., US RE

59 157 2923162 376291 247.01 Unnamed Brook Gray crest-stage gage

60 158 2940962 339060.4 69.07 Chenery Brook Cumberland crest-stage gage

61 159 2827942.4 372928.2 282.5 Stony Brook Rt. 11, at the streamflow-gaging station

62 160 2790435.1 355868.6 274.1 Saco River Rt. 117, at the streamflow-gaging station

63 161 2904990.5 311177.2 38.031 Presumpscot River Westbrook, at the streamflow-gaging station

1

27.73 feet NAVD 88 is flood stage at this location.
Prepared by the Pembroke Publishing Service Center.

For more information concerning this report, contact:

Director

U.S. Geological Survey

Maine Water Science Center

196 Whitten Road

Augusta, ME 04330

dc_me@usgs.gov

or visit our Web site at:

http://me.water.usgs.gov
Lombard—Flood of April 2007 in Southern Maine—Scientific Investigations Report 2009–5102

Printed on recycled paper