U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2008-5102

In cooperation with the Federal Emergency Management Agency, the Pennsylvania State 

Association of Township Supervisors, and the Susquehanna River Basin Commission 

Regression Equations for Estimating Flood Flows at Selected 

Recurrence Intervals for Ungaged Streams in Pennsylvania

Regression Equations for Estimating Flood 

Flows at Selected Recurrence Intervals for 

Ungaged Streams in Pennsylvania

By Mark A. Roland and Marla H. Stuckey

In cooperation with the Federal Emergency Management Agency, 

the Pennsylvania State Association of Township Supervisors, and 

the Susquehanna River Basin Commission

Scientific Investigations Report 2008–5102

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director 

U.S. Geological Survey, Reston, Virginia: 2008

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Suggested citation:

Roland, M.A., and Stuckey, M.H., 2008, Regression equations for estimating flood flows at selected recurrence intervals for ungaged streams in Pennsylvania: U.S. Geological Survey Scientific Investigations Report 2008-5102, 57 p.
iii

Contents

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

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

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

Previous Studies ...................................................................................................................................2

Development of Regression Equations ......................................................................................................2

Selection of Streamflow-Gaging Stations ........................................................................................2

Basin Characteristics...........................................................................................................................4

Regression Analysis.............................................................................................................................4

Flood-Flow Regression Equations...............................................................................................................4

Limitations of Regression Equations ........................................................................................................15

Summary........................................................................................................................................................15

Acknowledgments.......................................................................................................................................16

References Cited..........................................................................................................................................16

Appendix 1. Streamflow-gaging stations and basin characteristics used in development of

flood-flow regression equations for Pennsylvania streams ...................................................20

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from

observed streamflow-gaging data, predicted from regional regression equations, and

a weighted average for streamflow-gaging stations used in analysis .................................30

Appendix 3. Flood-flow magnitudes for selected recurrence intervals for

streamflow-gaging stations in Pennsylvania with drainage areas less than 2,000

square miles and streamflow substantially affected by upstream regulation.....................55

Figures

1-6. Maps showing 

1. Streamflow-gaging stations used in development of flood-flow regression

equations for Pennsylvania streams ..................................................................................3

2. Flood-flow regions and hydrologic unit code boundaries in Pennsylvania..................7

3. Flood-flow region 1 in Pennsylvania....................................................................................8

4. Flood-flow region 2 in Pennsylvania....................................................................................9

5. Flood-flow region 3 in Pennsylvania..................................................................................11

6. Flood-flow region 4 in Pennsylvania..................................................................................12
iv

Tables

1. Basin characteristics selected for use in the development of regression equations

for flood-flow estimates...............................................................................................................5

2. Number of streamflow-gaging stations and area in flood-flow regions in

Pennsylvania and surrounding states.....................................................................................10

3. Regression coefficients for use with flood-flow regression equations for

Pennsylvania streams................................................................................................................13

4. Equivalent period of record for regression equations developed for estimating flood

magnitudes for selected recurrence intervals in Pennsylvania.........................................14

5. Summary of the variables used to develop the flood-flow regression equations for

Pennsylvania ...............................................................................................................................15
v

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 square kilometer (km2) 

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

inch per hour (in/h) 0.0254 meter per hour (m/h)

Hydraulic gradient

foot per mile (ft/mi) 0.1894 meter per kilometer (m/km)

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.
vi
Abstract

Regression equations were developed for estimating flood flows at selected recurrence intervals for ungaged 

streams in Pennsylvania with drainage areas less than 

2,000 square miles. These equations were developed utilizing 

peak-flow data from 322 streamflow-gaging stations within 

Pennsylvania and surrounding states. All stations used in the 

development of the equations had 10 or more years of record 

and included active and discontinued continuous-record 

as well as crest-stage partial-record stations. The state was 

divided into four regions, and regional regression equations 

were developed to estimate the 2-, 5-, 10-, 50-, 100-, and 

500-year recurrence-interval flood flows. The equations were 

developed by means of a regression analysis that utilized basin 

characteristics and flow data associated with the stations.

Significant explanatory variables at the 95-percent confidence level for one or more regression equations included 

the following basin characteristics: drainage area; mean basin 

elevation; and the percentages of carbonate bedrock, urban 

area, and storage within a basin. The regression equations can 

be used to predict the magnitude of flood flows for specified 

recurrence intervals for most streams in the state; however, 

they are not valid for streams with drainage areas generally 

greater than 2,000 square miles or with substantial regulation, 

diversion, or mining activity within the basin. Estimates of 

flood-flow magnitude and frequency for streamflow-gaging 

stations substantially affected by upstream regulation are also 

presented. 

Introduction

Information on the frequency and magnitude of floods is 

essential for Flood Insurance Studies (FIS), flood-plain management, and the design of bridges and flood-control structures. Accurate and accessible methods that produce floodflow statistics are important to engineers and planners working 

on such projects. Flood-flow statistics commonly used in 

flood-related projects include the magnitude of flood flows 

occurring, on average, once in 2, 5, 10, 50, 100, and 500 years 

(Q2, Q5, Q10, Q50, Q100, and Q500, respectively). These 

flood flows are estimates based on statistical probabilities or 

frequencies, and the recurrence intervals associated with each 

flood flow refer to the average number of years between the 

floods (Dinicola, 1996). For example, the Q100 has a 1 in 100 

chance (or 0.01 probability or frequency) that a flood of this 

magnitude will occur in any given year.

Regression equations for computing the magnitude and 

frequency of peak flows were last developed for Pennsylvania 

by the U.S. Geological Survey (USGS) by use of peak-flow 

data collected through 1997 (Stuckey and Reed, 2000). Flooding experienced in the northern and eastern parts of Pennsylvania subsequent to 1997 prompted an analysis of floodmagnitude and flood-frequency data through the 2006 water 

year1 for streamflow-gaging stations with at least 25 years 

of record in the Delaware and Susquehanna River Basins in 

Pennsylvania (Roland and Stuckey, 2007). The results of that 

study, other recent flooding across the state, and advances in 

geospatially derived basin characteristics warranted updating 

the flood-flow regression equations for Pennsylvania.

The USGS, in cooperation with the Federal Emergency 

Management Agency (FEMA), the Pennsylvania State Association of Township Supervisors (PSATS), and the Susquehanna River Basin Commission (SRBC), developed updated 

flood-flow regression equations for use on ungaged streams in 

Pennsylvania. Regression equations were developed to estimate the Q2, Q5, Q10, Q50, Q100, and Q500 flood flows for 

streams without substantial regulation, diversion, or mining 

activity in the basin. This report discusses the methodology 

used and presents the results of the regression analysis.

Purpose and Scope

This report presents regression equations that describe 

the statistical relation between expected flood magnitudes 

and basin characteristics for selected recurrence intervals 

1

Water year is defined as a 12-month period beginning October 1 and ending September 30. The water year is designated by the calendar year in which 

it ends.

Regression Equations for Estimating Flood Flows at 

Selected Recurrence Intervals for Ungaged Streams in 

Pennsylvania

By Mark A. Roland and Marla H. Stuckey
2 Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania 

for ungaged streams in Pennsylvania. Flood-flow regression 

equations were developed by use of peak-flow data from 277 

continuous-record2 and 45 crest-stage partial-record3 streamflow-gaging stations in Pennsylvania and surrounding states—

New York, Ohio, Maryland, and West Virginia—with 10 or 

more years of record generally through the 2005 water year. 

Peak-flow data were used through the 2006 water year for 39 

stations in the Delaware and North Branch Susquehanna River 

Basins that experienced severe flooding in June 2006. Floodflow data are also presented for the Q2, Q5, Q10, Q50, Q100, 

and Q500 along with basin characteristics computed from the 

station data.

Previous Studies

 Regression equations used to predict flood frequencymagnitude relations for ungaged streams in Pennsylvania were 

first published by Flippo in 1977 and were updated by Flippo 

in 1982. The equations published in 1982 were evaluated by 

Ehlke and Reed (1999) on the basis of a comparison between 

flood flows calculated from the regression equations and peakflow data collected through the 1996 water year. Regression 

equations for estimating magnitude of flood flows in Pennsylvania for selected recurrence intervals were last published 

in 2000 using data through the 1997 water year (Stuckey and 

Reed, 2000). 

Development of Regression Equations

Flood flows for selected recurrence intervals were computed using peak streamflow data from gaging stations with 

flow relatively unaffected by regulation, diversion, or mining. 

Methods used are described in Water Resource Council Bulletin 17B (Water Resources Council, Hydrology Committee, 

1981). These flood flows will be referred to as “observed” in 

this report. The terms ‘peak flows’ and ‘flood flows’ may be 

used interchangeably in common parlance; however, within 

this report, an attempt is made to maintain consistency with 

regard to usage. The use of ‘peak flows’ is associated with 

flows that are more or less measured at a streamflow-gaging 

station and are associated with a period of observation (year). 

The term ‘flood flow’ is reserved for a more extreme event 

typically not measured directly and that is associated with a 

recurrence interval. 

Basin characteristics known to affect streamflow, such as 

land cover, were determined for the drainage basins upstream 

from the gaging stations. The observed flood flows (dependent 

2

Continuous-record station is a site where stage or streamflow is recorded 

at some interval on a continuous basis. The recording interval is usually 15 

minutes but may be less or more frequent.

3

Partial-record station is a site where discrete measurements of one or more 

hydrologic parameters are obtained over a period of time without continuous 

data being recorded or computed. A common example is a crest-stage gage 

partial-record station at which only peak stages and flows are recorded.

variable) were related to the basin characteristics (independent 

or explanatory variables) using regression techniques to obtain 

regression equations. These equations can be used to compute 

flood flows for selected recurrence intervals for streams where 

no gaging-station data are available. The flood flows computed from regression equations will be referred to as “predicted” in this report.

Selection of Streamflow-Gaging Stations

Peak-flow data generally through the 2005 water year 

from 306 stations on streams in Pennsylvania, along with 

peak-flow data from stations in surrounding states, including 

6 stations in New York, 5 in Ohio, 3 in Maryland, and 2 in 

West Virginia, with flow relatively unaffected by regulation, 

diversions, and mining were used in the development of the 

regression equations (fig. 1). In addition, peak-flow data for 

water year 2006 were used for 39 stations in the Delaware 

and North Branch Susquehanna River Basins that experienced 

severe flooding due to heavy rains occurring June 23, 2006, 

through June 29, 2006. 

Stations included in the analysis had 10 or more years 

of record and drainage areas less than 2,000 mi2. The stations 

were selected on the basis of information about regulation, 

diversions, and mining published in the USGS Pennsylvania 

Water Resources Data Reports, Surface-Water-Supply Reports, 

and other scientific reports. In the event of regulation, diversion, or mining occurring within a basin during the period of 

record, only the period of record prior to the event was used in 

the analysis. For stations that had a gap in the operational history, the total number of years the station was in actual operation was used to determine the period of record. A list of the 

stations used in the development of the regression equations is 

provided in appendix 1. 

Peak flows may be recorded outside of the streamflowgaging station operational period (also referred to as the 

systematic period of record) to document major flood events. 

These peaks are termed “historical peaks” and may be used 

to supplement the period of record at a station. If historical 

peaks are used in the analysis, the period of record at the station is adjusted to include the total number of years from the 

historical peak to the operational period of record, which may 

include a period when the station was not in operation (Water 

Resources Council, Hydrology Committee, 1981). This situation affected a small number of stations used in the analysis 

and typically added few years to the period of record. Because 

of the inherent uncertainty associated with historical peaks, 

not all historical peaks were included in the analysis. Typically, historical peaks were included in the analysis if the peak 

was not the maximum peak of record for the station or if the 

peak was recorded less than 5 years outside the period during 

which the station operated. Other factors such as knowledge 

about a particular event or previous USGS publications were 

considered as part of the decision to include a historical peak. 

For example, station 01539000, Fishing Creek near Blooms-
Development of Regression Equations 

3

Figure 1. Streamflow-gaging stations used in development of flood-flow regression equations for Pennsylvania streams.

PENNSYLVANIA

NEW YORK

OHIO

MARYLAND WEST VIRGINIA

NEW JERSEY

DELAWARE

VIRGINIA VIRGINIA

Base from U.S. Geological Survey 1:2,000,000 and 1:100,000 Digital DataState boundary from U.S. Geological Survey, 2005Rivers from U.S. Geological Survey, 2006

Albers Equal-Area Conic projection: Standard Parallels 29°30’N and 45°30’N.Central Meridian 77°45’W, Latitude of Origin 23°00’N

0 10 20 30 40 50 MILES0 10 20 30 40 50 KILOMETERS

75° 76° 77° 78° 79° 80° 81°

42°41°40°

STATE BOUNDARYCOUNTY BOUNDARYRIVER

CONTINUOUS-RECORD STREAMFLOW-GAGING STATIONCREST-STAGE PARTIAL-RECORD STREAMFLOW-GAGING STATION

EXPLANATION

LAKE ERIE

North Bra

cn

S

h

usquehanna

revi R

North Bra

cn

S

h

usquehanna

revi R
4 Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania 

burg, Pa., began continuous operation in 1939, but a historical 

peak was recorded in 1936. Subsequently, the period of record 

used in the analysis included the period between 1936 and 

1939, when the station was not in operation.

Basin Characteristics

A set of 24 climatologic, geologic, hydrologic, and 

physiographic basin characteristics with possible effects on 

peak flow was compiled from various geographic information 

system (GIS) sources. The use of GIS-derived basin characteristics in the development of regression equations improved 

consistency, reproducibility, and ease of use. The basin characteristics evaluated in the exploratory regression analysis are 

presented in table 1.

Regression Analysis

The observed flood-flow frequency statistics were 

computed for the 306 Pennsylvania stations and were related 

to the basin characteristics using exploratory Ordinary Least 

Squares (OLS) and Weighted Least Squares (WLS) regression 

techniques. The flood flows calculated for each streamflowgaging station for specified recurrence intervals were weighted 

for comparison purposes to OLS on the basis of the period of 

record, [(number of years of record at station * number of stations)/sum of years of record of all stations], and incorporated 

into the WLS analysis (Helsel and Hirsch, 1992). Regression 

iterations were performed using a statistical software package, S-PLUS (MathSoft, Inc., 1997), to reduce the number 

of explanatory variables to those significant at the 95-percent 

confidence level. Flood-flow and basin-characteristic data 

for the 16 out-of-state stations were obtained from previously 

published USGS reports (Dillow, 1996; Lumia and others, 

2006; Koltun, 2003; Wiley and others, 2000). Because limited 

data were available for these sites, they were excluded from 

the exploratory regression-analysis techniques. Each set of 

regression equations was constrained to contain the same 

explanatory variables in an attempt to maintain a monotonic 

relation between frequency and magnitude for all possible 

sites, whether the same explanatory variables were significant 

at all recurrence intervals. Diagnostics used to further evaluate the adequacy of the regression models included graphical 

relations, multicollinearity, standard error, and coefficient of 

determination (R2) (Helsel and Hirsch, 1992). 

The observed flood flows computed according to 

the guidelines in Bulletin 17B (Water Resources Council, 

Hydrology Committee, 1981) and the significant explanatory 

variables found using OLS and WLS were then related using 

a Generalized Least Squares (GLS) regression analysis to 

obtain the final regression equation. GLS is considered to be a 

more accurate regression technique for hydrologic regressions, 

particularly when using differing record lengths (Tasker and 

Stedinger, 1989). In addition to differing record lengths, the 

technique also takes into account variance of flows and crosscorrelation among the stations used in the analysis (Tasker and 

Stedinger, 1989). This regression technique was incorporated 

into a USGS software package, GLSNET (Tasker and Stedinger, 1989), and was used in this analysis. 

Flood-Flow Regression Equations

Data from 322 stations within Pennsylvania and from surrounding states were used to develop the Q2, Q5, Q10, Q50, 

Q100, and Q500 flood-flow regression equations. Exploratory 

regression analysis using OLS and WLS indicated the need for 

the state to be regionalized. A comparative analysis was done 

between the updated statewide regression residual values, 

standard errors, and R2 and those published by Stuckey and 

Reed (2000) for the previously developed flood-flow regions. 

Exploratory regressions using these previously defined floodflow regions in association with the updated peak-flow data 

did not produce diagnostic statistics indicative of a significant 

improvement over those resulting from the statewide regression developed using OLS and WLS for the updated Q100 

flood flow. Therefore, statewide regression residuals and basin 

flood-flow yields at the 100-year recurrence interval were 

used to create four flood-flow regions for the state (fig. 2). 

The basin flood-flow yields were computed for each station, 

in cubic feet per second per square mile, by dividing the Q100 

flood flow by the respective drainage area. The regionalization 

process consisted of generating plots of the Q100 regression 

residual values and basin flood-flow yields for each of the 322 

stations included in the study area. These plots were evaluated 

and regionalized on the basis of similar values. Physiographic 

provinces and precipitation maps were also used in the delineation of the four flood-flow regions. Hydrologic unit code 

(HUC8) boundaries were followed wherever possible while 

delineating the flood-flow regions to avoid dividing watersheds into multiple regions. The Schuylkill River Basin (HUC 

02040203) was divided on the basis of differing basin and 

geologic characteristics.

The North Branch Susquehanna River Basin, parts of 

the West Branch Susquehanna River Basin, and most of 

the northern Delaware River Basin are within flood-flow 

region 1 (fig. 3). The southern part of the Delaware River 

Basin, including Philadelphia and surrounding areas, and the 

lower part of the Susquehanna River Basin are within floodflow region 2 (fig. 4). The Schuylkill River Basin, within the 

Delaware River Basin, was split between regions 1 and 2; the 

upper part of the basin is in region 1 and the lower part, down 

to the mouth, is in region 2. This split was based on statewide 

regression diagnostics and differing hydrologic characteristics between the two parts of the basin. Flood-flow region 3 

extends from south-central Pennsylvania northwest to the state 

borders of New York, Ohio, and West Virginia, encompassing parts of the Susquehanna, Ohio, and St. Lawrence River 

Basins (fig. 5). The Potomac and parts of the Ohio River Basin 

in the southwestern part of Pennsylvania are within flood-flow 
Flood-Flow Regression Equations 5

Table 1. Basin characteristics selected for use in the development of regression equations for flood-flow estimates.—Continued

Basin characteristic Source Reference

Dependent Variables

Estimates of flood flows for the 2-, 5-, 10-, 

50-, 100-, and 500-year recurrence intervals (expressed in cubic feet per second)

Derived by application of PeakFQ computer program that 

performs statistical flood-frequency analyses of peak 

flows recorded at U.S. Geological Survey streamflowgaging stations following procedures recommended in 

Water Resources Council Bulletin 17B

streamflow data: 

U.S. Geological Survey 

(http://waterdata.usgs.gov/pa/

nwis/)

PeakFQ computer program: 

Flynn and others (2006)

Independent Variables

Basin slope (degrees) Digital Elevation Model (DEM) U.S. Geological Survey (2000a)

Mean basin elevation (feet) Digital Elevation Model (DEM) U.S. Geological Survey (2000a)

Forested (percent of basin area) National Land Cover Dataset (NLCD); and enhanced version (NLCDe) 

Homer and others (2004); Price 

and others (2003)

Glaciated (percent of basin area) From modified geology maps 

Pennsylvania Dept. of Conservation and Natural Resources (1997); Environmental 

Resources Research Institute 

(1996)

Lakes and open water (percent of basin 

area) 

National Land Cover Dataset (NLCD); and enhanced version (NLCDe); digitized from USGS quadrangle maps 

1:24000 scale

Homer and others (2004); Price 

and others (2003) 

Longest drainage path (mile) National Hydrography Dataset (NHD), 1:24000 scale U.S. Geological Survey (2000b)

Stream density (length, in miles, per basin 

area, in square miles) National Hydrography Dataset (NHD), 1:24000 scale U.S. Geological Survey (2000b)

Channel slope (feet per mile) Digital Elevation Model (DEM) U.S. Geological Survey (2000a)

Soil infiltration index (unitless, 1=well to 

4=poor) State Soil Geographic (STATSGO) database U.S. Department of Agriculture (1994)

Mean annual precipitation, 1971-2000 

(inches)

Parameter-elevation Regressions on Independent Slopes 

Model (PRISM) Daly (1996)

Drainage area (square miles) Digital Elevation Model (DEM) U.S. Geological Survey (2000a)

Soil thickness, depth to bedrock (feet) State Soil Geographic (STATSGO) database U.S. Department of Agriculture 

(1994)

Drainage run-off curve (unitless, 1=well to 

7=poor) State Soil Geographic (STATSGO) database U.S. Department of Agriculture (1994)

Soil available water content (percent) State Soil Geographic (STATSGO) database U.S. Department of Agriculture 

(1994)

Soil permeability (inches per hour) State Soil Geographic (STATSGO) database U.S. Department of Agriculture 

(1994)

Urbanized area (percent of basin area) National Land Cover Dataset (NLCD); and enhanced version (NLCDe) 

Homer and others (2004); Price 

and others (2003)

Residential area (percent of basin area) National Land Cover Dataset enhanced version (NLCDe) Price and others (2003)

Mined area (percent of basin area) National Land Cover Dataset enhanced version (NLCDe) Price and others (2003)

Commercial, industrial & transportation 

area (percent of basin area) National Land Cover Dataset enhanced version (NLCDe) Price and others (2003)

Wetlands (percent of basin area) National Land Cover Dataset (NLCD); and enhanced version (NLCDe) 

Homer and others (2004); Price 

and others (2003)

Ground-water head, defined as mean basin 

elevation minus minimum elevation 

(feet)

Digital Elevation Model (DEM) U.S. Geological Survey (2000a) 
6 Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania 

Table 1. Basin characteristics selected for use in the development of regression equations for flood-flow estimates.—Continued

Basin characteristic Source Reference

Shape factor (unitless) is a measure of the 

shape of a basin computed as the ratio of 

length of the basin to its computed area

Digital Elevation Model (DEM) U.S. Geological Survey (2000a)

Carbonate bedrock (percent of basin area) From modified geology maps

Pennsylvania Dept. of Conservation and Natural Resources (1997); Environmental 

Resources Research Institute 

(1996)

Impervious surface area (percent of basin 

area) National Land Cover Dataset (NLCD) Homer and others (2004)
Flood-Flow Regression Equations 

7

Figure 2. Flood-flow regions and hydrologic unit code boundaries in Pennsylvania.

PENNSYLVANIA

NEW YORK

OHIO

MARYLAND WEST VIRGINIA

NEW JERSEY

DELAWARE

VIRGINIA VIRGINIA

LAKE ERIE

3 1

4 2

Base from U.S. Geological Survey 1:2,000,000 and 1:100,000 Digital DataState boundary from U.S. Geological Survey, 2005Rivers from U.S. Geological Survey, 2006

Albers Equal-Area Conic projection: Standard Parallels 29°30’N and 45°30’N.Central Meridian 77°45’W, Latitude of Origin 23°00’N

0 10 20 30 40 50 MILES0 10 20 30 40 50 KILOMETERS

75° 76° 77° 78° 79° 80° 81°

42°41°40°

FLOOD-FLOW REGION BOUNDARYHYDROLOGIC UNIT CODE (HUC8) BOUNDARY

EXPLANATION

STATE BOUNDARYRIVER

Susquehanna River Susquehanna River

Delaware River l A el hg yne R vi er l A el hg yne R vi er

West Branch Susquehanna

R vi er

West Branch Susquehanna

R vi er

Oh oi River Oh oi River

Mon

no

hag e al

revi R

North Bra

cn

S

h

usquehanna

revi R

North Bra

cn

S

h

usquehanna

revi R
8 Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania 

Figure 3. Flood-flow region 1 in Pennsylvania.

1514000 1424500

1526000 1426000

1520000 1519200

1518862 1518000

1532850

1518420 1517000

1533800

1516350

1516500

1533250 1532000

1428750

1429300

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1429000

1533950 1430000 1534000 1548500

1534500

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1431500 1549500 1550000

1549780

1431680 1536000 1552500 1552100 1438300 1552000 1549000 1538800

1549700

1550500

1553005

1440300

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1440400 1447720

1553600

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1553700 1538000 1553130

1448000 1540000 1442500 1441000 1449500

1446600

1449360 1540200

1450000

1449000

1469500 1451000

1452300

1451800 1452500

1468500 1452000

1451650

1470720

1454600 1470500

1470756

1459500 1470779

1470960

1471000

1470853

1471510

1518500

1516800

1431000

1551000 1539000

1448500

1450500

1453000

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1514000 1424500

1526000 1426000

1520000 1519200

1518862 1518000

1532850

1518420 1517000

1533800

1516350

1516500

1533250 1532000

1428750

1429300

1429500

1532200

1429000

1533950 1430000 1534000 1548500

1534500

1430500

1431500 1549500 1550000

1549780

1431680 1536000 1552500 1552100 1438300 1552000 1549000 1538800

1549700

1550500

1553005

1440300

1447500

1553050

1439500

1440400 1447720

1553600

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1447680

1553700 1538000 1553130

1448000 1540000 1442500 1441000 1449500

1446600

1449360 1540200

1450000

1449000

1469500 1451000

1452300

1451800 1452500

1468500 1452000

1451650

1470720

1454600 1470500

1470756

1459500 1470779

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1471000

1470853

1471510

1518500

1516800

1431000

1551000 1539000

1448500

1450500

1453000

1451500

NEW YORK

PENNSYLVANIA NEW JERSEY

CONNECTICUT

ATLANT CI

OC AE N

PENNSYLVANIA

Delaware River

Nor ht B ar cn h Susquehanna revi RNor ht B ar cn h Susquehanna revi R Schuylkill River

Schuylkill River

Base from U.S. Geological Survey 1:2,000,000 and 1:100,000 Digital DataState boundary from U.S. Geological Survey, 2005Rivers from U.S. Geological Survey, 2006

Albers Equal-Area Conic projection: Standard Parallels 29°30’N and 45°30’N.Central Meridian 77°45’W, Latitude of Origin 23°00’N

0 10 20 30 40 50 MILES0 10 20 30 40 50 KILOMETERS

73° 74° 75° 76° 77° 78°

42°41°40°

FLOOD-FLOW REGION 1STATE BOUNDARYRIVER

Continuous-record streamflow-gaging stationCrest-stage partial-record streamflow-gaging station

EXPLANATION

STREAMFLOW-GAGING STATION WITH ABBREVIATEDSTATION NUMBER (FIRST NUMBER WAS REMOVED)

14493601519200
Flood-Flow Regression Equations 

9

Figure 4. Flood-flow region 2 in Pennsylvania.

Susquehanna River Susquehanna River

De al ware R vi er

1472620 1472198

1472199

1471980

1472000 1473000

1576320

1473100

1471875

1473120

1472157

1576085 1472174

1574000 1473169 1480300

1576500 1475300

1480800

1480500

1475850 1480610

1480617 1576754

1575000

1476480

1476500

1578400

1574500 1481000 1477000 1578200

1479820 1574800 1478200

1577500

1472620 1472198

1472199

1471980

1472000 1473000

1576320

1473100

1471875

1473120

1472157

1576085 1472174

1574000 1473169 1480300

1576500 1475300

1480800

1480500

1475850 1480610

1480617 1576754

1575000

1476480

1476500

1578400

1574500 1481000 1477000 1578200

1479820 1574800 1478200

1577500

Schuylkill River Schuylkill River

PENNSYLVANIA

NEW JERSEY

MARYLAND

DELAWARE

VIRGINIA

PENNSYLVANIA

Base from U.S. Geological Survey 1:2,000,000 and 1:100,000 Digital DataState boundary from U.S. Geological Survey, 2005Rivers from U.S. Geological Survey, 2006

Albers Equal-Area Conic projection: Standard Parallels 29°30’N and 45°30’N.Central Meridian 77°45’W, Latitude of Origin 23°00’N

0 5 10 15 20 25 MILES0 5 10 15 20 25 KILOMETERS

75° 76° 77°

40°39°

1465500

1473880 1465770

1473900

1467043

1465790

1465798

1467050

1465785

1467048

1465500

1473880 1465770

1473900

1467043

1465790

1465798

1467050

1465785

1467048

0 5 MILES0 5 KILOMETERS

De al ware R vi

re

FLOOD-FLOW REGION 2STATE BOUNDARYRIVER

Continuous-record streamflow-gaging stationCrest-stage partial-record streamflow-gaging station

EXPLANATION

STREAMFLOW-GAGING STATION WITH ABBREVIATEDSTATION NUMBER (FIRST NUMBER WAS REMOVED)

15775001473100

1467042

1473950

1474000

1467086

1467087

1467089

1475530

1475510

1475550

1467042

1473950

1474000

1467086

1467087

1467089

1475530

1475510

1475550

Philadelphia

County
10 Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania 

region 4 (fig. 6). The number of streamflow-gaging stations 

used to develop each flood-flow region and the area of each 

region are listed in table 2. The largest region is region 3, 

accounting for almost half the area in the state.

The following basin characteristics were statistically significant for one or more regression equations: drainage area, 

mean elevation, and the percentages of carbonate bedrock, 

urban area, and storage within the basin. A list of the basin 

characteristics for the stations used in the analysis is provided 

in appendix 1. When applying the regression equations to 

estimate flood magnitudes and frequency, it is important to 

maintain the same source of basin-characteristic data that were 

used in the development of the equations. Otherwise, the flood 

flows predicted by the regression equations may not be valid. 

To form a near-linear relation between the flood flows and 

basin characteristics, all independent and dependent variables 

were log-transformed prior to regression analysis. Because 

percentages can have a value of zero, 1.0 was added to the 

decimal form of the percentages of carbonate bedrock, urban 

area, and storage before the log transformation. Percentage of 

storage was derived from the percentage of lakes, ponds, and 

wetlands basin characteristics. To increase the variability of 

the basin characteristic storage area, a multiplication factor of 

10 was applied to the decimal form of the basin characteristic, in effect resulting in storage area being multiplied by 0.1 

rather than 0.01 prior to log transformation, as the other basin 

characteristics are. 

The regression model took the following form in log 

units:

Log Q A bLogDA cLogEl

dLog C eLog U

fLog

T

^

( . ) ( . )

(

= + + +

1 0 + + 01 1 0 + + 01

1 0 + . ) 1Sto (1)

Or, in arithmetic space:

A El C

U Sto

T

A b c d

e f

^

( ) ( ) ( . )

( . ) ( . )

= +

+ +

10 1 0 01

1 0 01 1 0 1

Q D

(2)

where

Log = log to base 10;

QT

^ 	 = the T-year predicted flood flow, in cubic feet

per second;

A = the intercept (estimated by GLS);

DA = drainage area, in square miles;

El = mean elevation, in feet;

C = basin underlain by carbonate bedrock, in 

percent;

U = urban area in the basin, in percent;

Sto = storage in the basin, in percent; and

b, c, d, e, and f = basin characteristic coefficients of

regression estimated by GLS.

Regression equations predicting flood magnitudes for the 

2-, 5-, 10-, 50-, 100-, and 500-year recurrence intervals were 

developed for each flood-flow region. The resultant basincharacteristic coefficients along with the standard errors of 

prediction for the regional flood-flow regression equations are 

shown in table 3. The standard errors of prediction provide an 

estimate of reliability of the predicted flood flows (Helsel and 

Hirsch, 1992). The standard errors of prediction for the floodflow regression equations ranged from 26 percent for the Q5 

in Region 4 to 49 percent for the Q500, also in Region 4. The 

standard errors of prediction for the Q100 ranged from 36 to 

38 percent.

Example using a flood-flow regression equation.

Example 1. Calculate the Q100 flood flow for a site near 

the confluence of Shohola Creek with the Delaware River 

in Pike County in the northeastern part of Pennsylvania at 

latitude 41°25’30” and longitude 74°57’20”. The drainage area 

Table 2. Number of streamflow-gaging stations and area in flood-flow regions in Pennsylvania and surrounding states.

Flood-flow 

region1

Area 

(square miles)

Number of in-state 

continuous-record 

stations

Number of 

out-of-state 

continuous-record 

stations

Number of in-state

partial-record 

stations

Total number 

of stations

1 12,216 73 4 14 91

2 4,356 50 0 5 55

3 22,020 105 7 20 132

4 6,710 33 5 6 44

Total 45,302 261 16 45 322

1

Flood-flow regions are shown on figure 2. 
Flood-Flow Regression Equations 11 Figure 5. Flood-flow region 3 in Pennsylvania.

4213000

PENNSYLVANIA

OHIO

NEW YORK

MARYLAND

3013000 3011020

4213200 3021410

3021350 4213075

3010500 3010655 4213040 3015390

3015000

3015080 3021700

3015280 3008000

3015500

3007800 3009680

3011800

3020440 3022500

3022540 3023000

1544450 3026500 3017500 1542810 3028000

1543700

3100000

3101000 3020500 1544500 3019000

3023500

3102950

3024000

3029000 1543000 1545600 3029500

3029400 1543500

3103000

3031780 3104000

1542720 3030500 3104760 3026400

3031000 3098700

1542500

1547950

1548005

1547700

1547800 1548020 3104500 3032500 3031950

1541500

1541200

15460001547200

3034000

3035000 1541000 3106500

1555000 1542000

3034500 1546400 3106000 3109000

3039000 1557500 3109500 1557100 1565000

3038000 1556500 3108000 1558000 1555500 3086100 1565700 1571820 1566500

1556400 1572000

1572025

1559500

1566000 1559000 1572190 1556000 1568500 1563000 1572900

1573000

3085500 1573500 1555800 1567500 1565920

1562500 1568000

1571000

1564512

1570000

1569800 1562000 1564500 3111150

1569340

1563800 1560000

1559790

1559700 1561000

3025000

3025200 3102500

3029200

1547500

1547100 1546500

1573160

1573560

1571500

MARYLAND

WEST

VIRGINIA

3013000 3011020

4213200 3021410

3021350 4213075

3010500 3010655 4213040 3015390

3015000

3015080 3021700

3015280 3008000

3015500

3007800 3009680

3011800

3020440 3022500

3022540 3023000

1544450 3026500 3017500 1542810 3028000

1543700

3100000

3101000 3020500 1544500 3019000

3023500

3102950

3024000

3029000 1543000 1545600 3029500

3029400 1543500

3103000

3031780 3104000

1542720 3030500 3104760 3026400

3031000 3098700

1542500

1547950

1548005

1547700

1547800 1548020 3104500 3032500 3031950

1541500

1541200

15460001547200

3034000

3035000 1541000 3106500

1555000 1542000

3034500 1546400 3106000 3109000

3039000 1557500 3109500 1557100 1565000

3038000 1556500 3108000 1558000 1555500 3086100 1565700 1571820 1566500

1556400 1572000

1572025

1559500

1566000 1559000 1572190 1556000 1568500 1563000 1572900

1573000

3085500 1573500 1555800 1567500 1565920

1562500 1568000

1571000

1564512

1570000

1569800 1562000 1564500 3111150

1569340

1563800 1560000

1559790

1559700 1561000

3025000

3025200 3102500

3029200

1547500

1547100 1546500

1573160

1573560

1571500

LAKE ERIE

Oh oi River

A ll hge yne

R vi re

West Branch Susquehanna River

PENNSYLVANIA

Base from U.S. Geological Survey 1:2,000,000 and 1:100,000 Digital DataState boundary from U.S. Geological Survey, 2005Rivers from U.S. Geological Survey, 2006

Albers Equal-Area Conic projection: Standard Parallels 29°30’N and 45°30’N.Central Meridian 77°45’W, Latitude of Origin 23°00’N

0 10 20 30 40 50 MILES

0 10 20 30 40 50 KILOMETERS

76° 77° 78° 79° 80° 81° 82°

42°41°40°

FLOOD-FLOW REGION 3STATE BOUNDARYRIVER

Continuous-record streamflow-gaging stationCrest-stage partial-record streamflow-gaging station

EXPLANATION

STREAMFLOW-GAGING STATION WITH ABBREVIATEDSTATION NUMBER (FIRST NUMBER WAS REMOVED)

31090003015390
12 Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania 

Figure 6. Flood-flow region 4 in Pennsylvania.

3049000

3042170

3042200 3047500 3049800

3042500

3043000

3042000

3084000

3045500 3084500

3041000

3045000 3040000 3083500

3083600

3083000

3039200

3082500

3082200 3072840

3074500

3072880

1614090 1600700

3073000 1613050

3074300

3079000

3080000

1601000 1638900

3072590

1603500 3070420 3072000

3078500

1613500

1614500 1601500

3062500

3070500

3041500

3078000

3049000

3042170

3042200 3047500 3049800

3042500

3043000

3042000

3084000

3045500 3084500

3041000

3045000 3040000 3083500

3083600

3083000

3039200

3082500

3082200 3072840

3074500

3072880

1614090 1600700

3073000 1613050

3074300

3079000

3080000

1601000 1638900

3072590

1603500 3070420 3072000

3078500

1613500

1614500 1601500

3062500

3070500

3041500

3078000

OHIO PENNSYLVANIA

WEST VIRGINIA

VIRGINIA

MARYLAND

DISTRICT OFCOLUMBIA

Mon no hag e

R al

vi re

PENNSYLVANIA

Base from U.S. Geological Survey 1:2,000,000 and 1:100,000 Digital DataState boundary from U.S. Geological Survey, 2005Rivers from U.S. Geological Survey, 2006

Albers Equal-Area Conic projection: Standard Parallels 29°30’N and 45°30’N.Central Meridian 77°45’W, Latitude of Origin 23°00’N

0 10 20 30 40 50 MILES0 10 20 30 40 50 KILOMETERS

77° 79° 80° 81° 78°

41°40°39°

FLOOD-FLOW REGION 4STATE BOUNDARYRIVER

Continuous-record streamflow-gaging stationCrest-stage partial-record streamflow-gaging station

EXPLANATION

STREAMFLOW-GAGING STATION WITH ABBREVIATED STATION NUMBER (FIRST NUMBER WAS REMOVED)

30822003042170
Flood-Flow Regression Equations 13

Table 3. Regression coefficients for use with flood-flow regression equations for Pennsylvania streams.

[ft3/s, cubic feet per second; --, basin characteristic not significant]

T-year 

peak flow 

(ft3/s)

Intercept

Basin-characteristic coefficients Standard error of 

prediction Coefficient 

of 

determination 

(R2)

Drainage 

area1

Mean 

elevation2

Percent 

carbonate 

bedrock3

Percent 

urban 

area4

Percent 

storage5

Log units Percent

Region 1

Q2 1.84257 0.86396 -- -- -- -0.49180 0.14 33 0.95

Q5 2.10658 .84127 -- -- -- -.49148 .13 31 .95

Q10 2.24305 .83197 -- -- -- -.47595 .13 31 .95

Q50 2.47845 .81981 -- -- -- -.43501 .15 36 .92

Q100 2.56172 .81626 -- -- -- -.41724 .16 38 .90

Q500 2.73185 .81002 -- -- -- -.37550 .19 46 .85

Region 2

Q2 2.20340 .69782 -- -0.47534 0.91196 -- .17 41 .88

Q5 2.50745 .66365 -- -.65666 .56109 -- .15 36 .89

Q10 2.66804 .64853 -- -.75941 .39037 -- .14 33 .88

Q50 2.94676 .62615 -- -.92098 .11100 -- .14 33 .84

Q100 3.04617 .61864 -- -.97299 .00947 -- .15 36 .81

Q500 3.25362 .60294 -- -1.07780 -.21084 -- .17 41 .71

Region 3

Q2 3.27469 .82143 -0.4517 -1.96079 -- -.74815 .13 31 .96

Q5 3.73436 .79492 -.51761 -1.78595 -- -.90039 .12 28 .96

Q10 3.98972 .78127 -.55653 -1.66440 -- -.99420 .12 28 .96

Q50 4.42545 .75816 -.62224 -1.45536 -- -1.15401 .13 31 .93

Q100 4.5808 .75043 -.64613 -1.38215 -- -1.20941 .15 36 .92

Q500 4.90955 .73500 -.69814 -1.22437 -- -1.32521 .18 43 .87

Region 4

Q2 1.82330 .84471 -- -- -- -- .12 28 .97

Q5 2.09191 .81363 -- -- -- -- .11 26 .97

Q10 2.23878 .79689 -- -- -- -- .12 28 .96

Q50 2.50038 .77079 -- -- -- -- .14 33 .94

Q100 2.59407 .76279 -- -- -- -- .16 38 .93

Q500 2.78822 .74809 -- -- -- -- .20 49 .88

1

 Drainage area, in square miles, determined from 30-meter digital elevation model (DEM).

2

 Mean elevation, in feet, is the average elevation in the basin, determined from 30-meter DEM.

3

 Percent carbonate bedrock is the percent of basin underlain by carbonate bedrock, determined by modified geology maps.

4

 Percent urban area is the percent of urban area, as defined by low-intensity residential, high-intensity residential, commercial/industrial/transportation, residential with trees, and residential without trees in the basin, determined by National Land Cover Dataset enhanced (NLCDe).

5

 Percent storage is the percent of lakes, ponds, and wetlands, determined from U.S. Geological Survey 1:24,000 quadrangles and NLCDe.
14 Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania 

is 77.0 mi2, and the percent storage is 10.2. The basin is unaffected by substantial regulation, diversion, or mining.

1. From figure 2 and the latitude and longitude, the 

site is in flood-flow region 1.

2. Using coefficients from table 3, the Q100 

regional regression equation is:

logQ

^

100 = 2.56172 + 0.81626 log(DA) – 

 0.41724 log(1 + (0.1 × Sto))

3. Substituting the basin characteristics for the site 

into the equation produces:

logQ

^

100 = 2.56172 + 0.81626 log(77.0) - 

 0.41724 log(1 + (0.1 × 10.2))

logQ

^

100 = 2.56172 + (1.53987) - (0.12740) 

logQ

^

100 = 3.97419

Q

^

100 = 9,420 ft3

/s

Just as a station has a period of record that should be 

taken into consideration when computing flood frequencies 

from gaging-station peak-flow data, regression equations have 

an equivalent period of record that should be taken into consideration when using the equations to compute flood frequencies. The equivalent years of record provide indicators of the 

accuracy of the regression equations. The equivalent years of 

record are computed from a factor that is based on the skew 

coefficient of the population of annual peaks, the standard 

deviation of the logarithms of the annual peaks at individual 

stations used in the development of the regression equations, 

and the standard error of prediction of the regression equations. This methodology is presented by Hardison (1971). The 

equivalent years of record for each of the regression equations 

are shown in table 4. For the Q100, the equivalent period 

of record ranges from 11 years for Region 3 to 15 years for 

Region 2. To summarize, the Q100 calculated from the equation developed for Region 3 is comparable to the Q100 determined from a record from a station that has been in operation 

for 11 years.

A weighted method to minimize the temporal bias 

associated with stations has been suggested by Flippo (1977), 

Stuckey and Reed (2000), Water Resources Council, Hydrology Committee (1981), and others to compute flood-flow 

statistics for a streamflow-gaging station. Observed flood 

frequency-magnitude estimates may contain time-sampling 

variability because of the specific time span associated with 

the period of record for a station. The period of record for 

a station may or may not include years when large floods 

occurred. Inclusion of several large floods, or lack of any 

large floods, can change flood frequency-magnitude estimates 

for stations, especially those with short periods of record. To 

minimize this bias, a method has been developed that incorporates the observed, as well as the predicted, flood flows into 

a weighted average flood-frequency discharge estimate using 

the period of record of the station and the equivalent period of 

record for the regression equation.

 The weighted average discharge estimates are computed 

from the equation: 

Q

Q N Q NE

N NE T W

T G T R

( )

( ) ( )

( ) =

( )+ ( )

+

^

where

QT(W)	 = the weighted flood discharge for the T-year

recurrence interval, in cubic feet per 

second;

QT(G)	 = the observed flood discharge computed

from streamflow-gaging-station data for

the T-year recurrence interval, in cubic feet 

Table 4. Equivalent period of record for regression equations developed for estimating flood magnitudes for selected recurrence 

intervals in Pennsylvania.

[Methodology used described by Hardison (1971); flood-flow regions are shown in figure 2]

Flood-recurrence 

interval

Equivalent period of record (years)

Flood-flow region 1 Flood-flow region 2 Flood-flow region 3 Flood-flow region 4

2-year 3 2 3 4

5-year 6 4 5 7

10-year 9 7 7 10

50-year 13 13 11 13

100-year 13 15 11 13

500-year 14 16 11 12
Limitations of Regression Equations 15

per second;

N = the number of years of record at the 

streamflow-gaging station used to calculate 

QT(G);

QT R

^

( ) = the predicted flood discharge computed 

from regression equations for the T-year 

recurrence interval, in cubic feet per 

second; and

NE = average equivalent years of record 

associated with the regression equation in 

table 4.

Example showing the calculation of weighted flood flows.

Example 2. Calculate the weighted flood-frequency 

discharge estimate for streamflow-gaging station 01546400, 

Spring Creek at Houserville, Pa., at latitude 40°50’01” and 

longitude 77°49’40”. The drainage area is 58.5 mi2, mean elevation is 1,340 ft, percentage of carbonate bedrock is 75.1, and 

the basin contains 0.13 percent storage. The station operated 

from 1985 to 2005 as a continuous-record station, for a total of 

21 years. The basin is unaffected by regulation, diversion, or 

mining. The reported Q100 determined from streamflow data 

is 2,840 ft3/s.

1. The Q100 computed from the regional regression 

equation is 3,500 ft3/s (see Example 1 for methodology), and from table 4, the equivalent years 

of record for the regression equation is 11 years.

2. Substituting the discharges and number of years 

into equation 2 produces:

Q100(W) = [(2,840 × 21) + (3,500 × 11)] / (21 + 11)

Q100(W) = 3,070 ft3/s

The observed, predicted, and weighted flood flows for 

the stations used in the analysis are shown in appendix 2. 

Additional techniques for estimating magnitude of flood flows 

at selected recurrence intervals in Pennsylvania under other 

situations have been identified by Stuckey and Reed (2000).

Limitations of Regression Equations

Certain conditions can limit the application of the regression equations presented in this report. The equations should 

not be used if the drainage area is less than 1.0 mi2 or greater 

than 2,000 mi2. Regions 1, 3, and 4 do not include a variable for percentage of urban development in the regression 

equations, and as a result, effects from urbanization may not 

be captured in regression-equation results for these regions. 

A summary of the range of all the variables used to develop 

the regression equations is presented in table 5. Predicted 

streamflow characteristics for basins with basin characteristics 

outside these ranges may not be valid. Particularly, regression equations developed for regions 1 and 3 are sensitive to 

percent storage, and results from these regression equations 

should be reviewed carefully to determine accuracy for basins 

with percent storage outside the range listed in table 5. When 

applying the regression equations to estimate flood magnitudes and frequency, it is important to maintain the same 

source of basin-characteristic data that were used in the development of the equations. Otherwise, the flood flows predicted 

by the regression equations may not be valid. 

The regression equations should not be used to predict 

flood flows if streamflow at the site of interest is substantially 

affected by an upstream flood-control reservoir. The streamflow-gaging stations that were excluded from the regression 

analysis because of substantial upstream regulation are listed 

in appendix 3 with observed flood flows for specified recurrence intervals. The 500-year recurrence flow is not listed in 

the appendix because the storage capacity for some floodcontrol reservoirs may not be sufficient to store all the runoff 

associated with the 500-year flood event.

Summary

Flood-flow statistics provide the foundation for Flood 

Insurance Studies (FIS), flood-plain management, and the 

design of bridges and flood-control structures. Accessible 

Table 5. Summary of the variables used to develop the flood-flow regression equations for Pennsylvania.

[mi2, square miles; ft, feet]

Flood-flow 

region

Number of 

stations 

used

Range of basin-characteristic variables

Drainage 

area 

(mi2)

Mean 

elevation 

(ft)

Percent 

urban area 

Percent 

carbonate 

bedrock

Percent 

storage

1 91 1.72 - 1,280 0 - 1,960 0 - 20 0 - 83 0 - 21.2

2 55 2.02 - 1,150 113 - 901 0 - 94 0 - 67 0 - 3.6

3 132 1.44 - 1,610 457 - 2,150 0 - 64 0 - 99 0 - 22.6

4 44 .92 - 1,720 553 - 2,700 0 - 67 0 - 42 0 - 2.4
16 Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania 

methods that produce estimates of the frequency and magnitude of floods are important to engineers and planners working 

on such projects. The USGS, in cooperation with the Federal 

Emergency Management Agency (FEMA), the Pennsylvania 

State Association of Township Supervisors (PSATS), and the 

Susquehanna River Basin Commission (SRBC), developed 

flood-flow regression equations to estimate flood flows for 

ungaged streams in Pennsylvania using data from 322 continuous-record and crest-stage partial-record streamflow-gaging 

stations with 10 or more years of record in Pennsylvania and 

surrounding states.

Regression equations were developed to estimate the 

Q2, Q5, Q10, Q50, Q100, and Q500 flood discharges for four 

flood-flow regions in Pennsylvania. The following basin characteristics were significant at the 95-percent confidence level 

for one or more regression equations: drainage area, mean 

elevation, and the percentages of carbonate bedrock, urban 

area, and storage within the basin. Standard errors of prediction ranged from 26 percent for the Q5 in Region 4 to 49 percent for the Q500, also in Region 4. The equivalent periods of 

record for the Q100 regression equations ranged from 11 years 

for Region 3 to 15 years for Region 2. To minimize temporal 

bias that may be associated with a station, a weighting method 

is presented that incorporates the observed, as well as the predicted, flood flows into a weighted-average flood-frequency 

discharge estimate. 

Certain conditions can limit the application of the regression equations presented in this report. The equations should 

not be used if the contributing drainage area is less than 

1.0 mi2 or greater than 2,000 mi2. The regression equations 

should not be used to predict flood-flow frequency statistics 

if streamflow at the site of interest is substantially affected 

by an upstream flood-control reservoir. Estimates of floodflow magnitude for streamflow-gaging stations substantially 

affected by upstream regulation are presented. Predicted 

streamflow characteristics for basins with basin characteristics 

outside the ranges used to develop the regression equations 

may not be valid.

Acknowledgments

Special thanks are extended to the USGS Pennsylvania 

Water Science Center (and Maryland, New York, Ohio, West 

Virginia) Hydrologic Surveillance Program staffs for their 

compilation and meticulous review of station data that were 

used to determine the observed flood frequencies. David 

Holtschlag (USGS Michigan Water Science Center) and Kara 

Watson (USGS New Jersey Water Science Center) provided 

critical colleague reviews.

References Cited

Daly, Christopher, 1996, Overview of the PRISM 

Model [online]: accessed June 24, 2008, at 

http://www.prism.oregonstate.edu/docs/tech_desc.html

Dillow, J.J.A., 1996, Technique for estimating magnitude and 

frequency of peak flows in Maryland: U.S. Geological Survey Water-Resources Investigations Report 95-4154, 55 p. 

Dinicola, Karen, 1996, The “100-Year Flood”: U.S. Geological Survey Fact Sheet 229-96, 2 p.

Ehlke, M.H., and Reed, L.A., 1999, Comparison of methods for computing streamflow statistics for Pennsylvania 

streams: U.S. Geological Survey Water-Resources Investigations Report 99-4068, 80 p.

Environmental Resources Research Institute, 1996, Areas of 

carbonate lithology (limeston.zip): Pennsylvania Department of Environmental Protection, accessed June 24, 2008, 

at ftp://www.pasda.psu.edu/pub/pasda/compendium/.

Flippo, H.N., Jr., 1977, Floods in Pennsylvania: Harrisburg, 

Pa., Pennsylvania Department of Environmental Resources, 

Water Resources Bulletin No. 13, 59 p.

Flippo, H.N., Jr., 1982, Evaluation of the streamflow data 

program in Pennsylvania: U.S. Geological Survey WaterResources Investigations 82-21, 56 p.

Flynn, K.M., Kirby, W.H., and Hummel, P.R., 2006, Users 

manual for PeakFQ, annual flood frequency analysis using 

Bulletin 17B Guidelines: U.S. Geological Survey Techniques and Methods Report, book 4, chap. B4, 42 p.

Hardison, C.H., 1971, Prediction error of regression estimates 

of streamflow characteristics at ungaged sites, in Geological 

Survey Research 1971: U.S. Geological Survey Professional Paper 750-C, p. C228-C236. 

Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in 

water resources: Amsterdam, The Netherlands, Elsevier, 

Sarah Burgerhartstraat 25, 1000 AE Studies in Environmental Science 49, 529 p.

Homer, C., Huang, C., Yang, L., Wylie, B., and Coan, M., 

2004, Development of a 2001 National Landcover Database for the United States: Photogrammetric Engineering 

and Remote Sensing, v. 70, no. 7, July 2004, p. 829-840, 

accessed October 24, 2007, at http://www.mrlc.gov/

mrlc2k_publications.asp

Koltun, G.F., 2003, Techniques for estimating flood-peak discharges of rural, unregulated streams in Ohio (2d ed.): U.S. 

Geological Survey Water-Resources Investigations Report 

03-4164, 75 p.
References Cited 17

Lumia, Richard, Freehafer, D.A., and Smith, M.J., 2006, 

Magnitude and frequency of floods in New York: U.S. 

Geological Survey Scientific Investigations Report 2006-

5112, 152 p. 

MathSoft, Inc., 1997, S-PLUS user’s guide: Seattle, Wash., 

Data Analysis Products Division, MathSoft, 620 p.

Pennsylvania Department of Conservation and Natural Resources, 1997, Glacial deposits of Pennsylvania: Bureau of Topographic and Geologic Survey, accessed February 28, 2008, at 

http://www.dcnr.state.pa.us/topogeo/field/glacial.aspx

Price, C., Nakagaki, N., Hitt, K., and Clawges, R., 2003, Mining GIRAS—Improving on a national treasure of land use 

data: ESRI International User Conference 2003 Proceedings, accessed October 3, 2005, at http://gis.esri.com/

library/userconf/proc03/p0904.pdf

Roland, M.A., and Stuckey, M.H., 2007, Analysis of floodmagnitude and flood-frequency data for streamflow-gaging 

stations in the Delaware and North Branch Susquehanna 

River Basins in Pennsylvania: U.S. Geological Survey 

Open-File Report 2007-1235, 22 p.

Stuckey, M.H., and Reed, L.A., 2000, Techniques for estimating magnitude and frequency of peak flows for Pennsylvania streams: U.S. Geological Survey Water-Resources 

Investigations Report 00-4189, 43 p.

Tasker, G.D., and Stedinger, J.R., 1989, An operational GLS 

model for hydrologic regression: Journal of Hydrology, 

v. 3, p. 361-375.

U.S. Department of Agriculture, 1994, State Soil Geographic 

(STATSGO) data base for Pennsylvania [online]: accessed 

January 17, 2006, at http://www.ncgc.nrcs.usda.gov/

products/datasets/statsgo

U.S. Geological Survey, 2000a, US GeoData Digital Elevation 

Models: U.S. Geological Survey Fact Sheet 040-00, 3 p., 

accessed January 30, 2006, at http://erg.usgs.gov/isb/pubs/

factsheets/fs04000.html

U.S. Geological Survey, 2000b, The National Hydrography Dataset [online]: accessed January 3, 2006, at 

http://nhd.usgs.gov/chapter1/index.html

Water Resources Council, Hydrology Committee, 1981, 

Guidelines for determining flood flow frequencies: Washington, D.C., Bulletin 17B, variously paged.

Wiley, J.B., Atkins, J.T., Jr., and Tasker, G.D., 2000, Estimating magnitude and frequency of peak discharges for rural, 

unregulated streams in West Virginia: U.S. Geological Survey Water-Resources Investigations Report 00-4080, 70 p.
18 Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania 
References Cited 19

Appendixes

Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for 

Pennsylvania streams. 

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging data, predicted 

from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis. 

Appendix 3. Flood-flow magnitudes for selected recurrence intervals for streamflow-gaging stations in Pennsylvania with drainage 

areas less than 2,000 square miles and streamflow substantially affected by upstream regulation. 
20 Regression Equations for Estimating Flood Flows at Selected Recurrence Intervals Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued [C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis] U.S. Geological Survey streamflow- gaging station number Type Latitude (ddmmss) Longitude (ddmmss) Station name Period of record1 (water year)2 Number of years used in analysis3 Basin characteristics Drainage area (mi2

)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

01424500

C 420545 751925 Trout Creek at Cannonsville, N.Y. 1941-1963 23 49.5 -- -- 3.04 0

01426000

C 420331 752542 Oquaga Creek at Deposit, N.Y. 1941-2005 35 67.6 -- -- .56 0

01428750

C 414028 752235 West Branch Lackawaxen River near Aldenville, Pa. 1975-2006 32 40.6 1,750 0 1.95 .28

01429000

C 413514 751938 West Branch Lackawaxen River at Prompton, Pa. 1942-2005 16 59.7 1,650 0 5.43 .37

01429300 P 413926 751712 Dyberry Creek above Reservoir near Honesdale, Pa. 1975-2004 28 46.1 1,500 0 2.27 .2101429500

C 413626 751603 Dyberry Creek near Honesdale, Pa. 1942-2005 16 64.6 1,470 0 3.57 .21

01430000

C 413343 751454 Lackawaxen River near Honesdale, Pa. 1942-2005 11 164 1,510 0 4.88 1.43

01430500

C 412910 751115 Lackawaxen River at West Hawley, Pa. 1922-1942 17 198 1,470 0 4.53 1.66

01431000

C 412905 751320 Middle Creek near Hawley, Pa. 1945-1986 41 78.4 1,400 0 6.95 .67

01431500

C 412834 751021 Lackawaxen River at Hawley, Pa. 1909-1959 51 290 1,440 0 5.17 1.53

01431680 P 412315 751420 Mill Brook near Paupack, Pa. 1960-1980 20 4.84 1,540 0 3.57 2.0501438300 P 411935 744750 Vandermark Creek at Milford, Pa. 1962-2006 45 5.09 1,060 0 .75 5.3101439500

C 410515 750220 Bush Kill at Shoemakers, Pa. 1909-2006 98 117 1,270 0 11.25 3.65

01440300 P 410950 751600 Mill Creek at Mountainhome, Pa. 1961-2006 46 5.9 1,620 0 1.29 12.801440400

C 410505 751254 Brodhead Creek near Analomink, Pa. 1958-2006 49 65.9 1,380 0 5.12 3.7

01441000

C 405845 751205 McMichael Creek near Stroudsburg, Pa. 1911-1955 28 65.3 952 .23 3.34 3.17

01442500

C 405955 750835 Brodhead Creek at Minisink Hills, Pa. 1951-2006 56 259 1,130 .06 3.97 8.29

01446600

C 405400 751208 Martins Creek near East Bangor, Pa. 1961-1986 26 10.4 947 0 7.34 .06

01447500

C 410749 753733 Lehigh River at Stoddartsville, Pa. 1942-2006 65 91.7 1,830 0 14.04 7.47

01447680

C 410355 753114 Tunkhannock Creek near Long Pond, Pa. 1966-2006 40 20 1,880 0 21.24 .74

01447720

C 410505 753621 Tobyhanna Creek near Blakeslee, Pa. 1955-2006 45 118 1,850 0 18.32 9.9

01448000

C 410225 754542 Lehigh River at Tannery, Pa. 1915-1959 45 320 1,790 0 13.28 6.76

01448500

C 410208 753237 Dilldown Creek near Long Pond, Pa. 1949-2006 58 2.39 1,890 0 5.08 .42

01449000

C 404945 754220 Lehigh River at Lehighton, Pa. 1982-2006 25 589 1,640 0 8.68 6.23

01449360

C 405351 753010 Pohopoco Creek at Kresgeville, Pa. 1967-2006 40 49.9 1,060 0 1.93 7.3

01449500

C 405522 753332 Wild Creek at Hatchery, Pa. 1941-1978 18 16.8 1,390 0 5.66 .55

01450000

C 404954 754053 Pohopoco Creek near Parryville, Pa. 1941-1970 29 109 1,070 0 4.03 4.11

01450500

C 404822 753554 Aquashicola Creek at Palmerton, Pa. 1940-2006 67 76.7 867 4.91 1.32 2.03

01451000

C 404525 753612 Lehigh River at Walnutport, Pa. 1942-2005 14 889 1,400 .74 6.51 5.54

01451500

C 403456 752860 Little Lehigh Creek near Allentown, Pa. 1935-2006 61 80.8 532 63.7 .73 13

01451650

C 403547 752828 Little Lehigh Creek at Tenth St. Br. at Allentown, Pa. 1987-2006 20 98 509 69.4 .76 19.8

01451800

C 403942 753738 Jordan Creek near Schnecksville, Pa. 1967-2006 40 53 675 0 .35 1.79

01452000

C 403723 752858 Jordan Creek at Allentown, Pa. 1945-2006 62 75.8 620 11.3 .42 4.96

01452300

C 404310 752210 East Branch Monocacy Creek near Bath, Pa. 1963-1981 19 5.53 623 19.5 1.06 7.36

01452500

C 403828 752247 Monocacy Creek at Bethlehem, Pa. 1945-2006 62 44.5 494 62.8 .94 12.8
Appendix 1 21

Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued[C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis]

U.S. Geological 

Survey 

streamflowgaging station 

number

Type Latitude (ddmmss) Longitude (ddmmss) Station name

Period of 

record1

(water 

year)2

Number of 

years used 

in analysis3

Basin characteristics

Drainage 

area 

(mi2)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

01453000 C 403655 752245 Lehigh River at Bethlehem, Pa. 1906-2005 51 1,280 1,170 11 4.92 8.401454600 C 403405 751945 Polk Valley Run at Hellertown, Pa. 1963-1980 18 1.72 649 23.2 1.09 .0201459500 C 402601 750701 Tohickon Creek near Pipersville, Pa. 1936-2005 38 97.4 509 0 5.03 4.8601465500 C 401026 745726 Neshaminy Creek near Langhorne, Pa. 1933-2006 74 210 305 1.83 1.00 26.801465770 C 400755 745940 Poquessing Creek at Trevose Road, Phila., Pa. 1965-1981 17 5.09 215 4.31 .55 9001465785 C 400522 745937 Walton Run at Philadelphia, Pa. 1965-1978 14 2.17 142 0 .79 67.101465790 C 400454 745857 Byberry Creek at Chalfont Road, Phila., Pa. 1966-1978 13 5.34 133 0 1.97 6801465798 C 400325 745908 Poquessing Creek at Grant Ave. at Philadelphia, Pa. 1966-2006 41 21.4 133 1.03 2.57 76.301467042 C 400523 750410 PennyPack Creek at Pine Road, at Philadelphia, Pa. 1965-1981 17 37.9 260 1.88 .81 72.401467043 C 400527 750315 Stream ‘A’ at Philadelphia, Pa. 1965-1980 16 2.7 175 0 .60 94.401467048 C 400300 750159 PennyPack Cr at Lower Rhawn St Bdg, Phila., Pa. 1966-2006 41 49.8 233 1.43 .88 74.401467050 C 400319 750122 Wooden Bridge Run at Philadelphia, Pa. 1965-1981 17 3.36 113 0 .66 6701467086 C 400247 750640 Tacony Creek at County Line, Philadelphia, Pa. 1966-1986 21 16.6 254 0 .54 86.701467087 C 400057 750550 Frankford Creek at Castor Ave, Philadelphia, Pa. 1982-2005 24 30.4 220 0 .34 88.801467089 C 400025 750533 Frankford Creek at Torresdale Ave., Phila., Pa. 1966-1981 16 33.8 206 0 .36 89.601468500 C 403745 760730 Schuylkill River at Landingville, Pa. 1942-2006 42 133 1,110 0 1.56 8.6101469500 C 404825 755820 Little Schuylkill River at Tamaqua, Pa. 1920-2006 87 42.9 1,380 0 2.64 3.9601470500 C 403121 755955 Schuylkill River at Berne, Pa. 1942-2006 65 355 1,020 .12 1.74 5.7401470720 C 403423 755234 Maiden Creek Tributary at Lenhartsville, Pa. 1962-1980 18 7.46 642 0 .21 .8701470756 C 403051 755260 Maiden Creek at Virginville, Pa. 1973-1995 23 159 665 10.8 .80 1.3401470779 C 402448 761019 Tulpehocken Creek near Bernville, Pa. 1972-2006 33 66.5 523 83.2 .68 4.5101470853 C 402024 760837 Furnace Creek at Robesonia, Pa. 1983-2005 23 5.7 978 0 .40 .0301470960 C 402214 760132 Tulpehocken Cr at Blue Marsh Damsite near Reading, Pa.. 1965-2005 14 175 544 42.1 1.94 3.0801471000 C 402208 755846 Tulpehocken Creek near Reading, Pa. 1951-2005 28 211 529 41.3 1.70 3.9401471510 C 402005 755612 Schuylkill River at Reading, Pa. 1757-1930 29 880 740 19 1.54 5.5601471875 C 402022 754433 Manatawny Creek near Spangsville, Pa. 1994-2006 13 56.9 670 28.5 1.40 1.5501471980 C 401622 754049 Manatawny Creek near Pottstown, Pa. 1972-2006 32 85.5 588 26.1 1.04 2.2201472000 C 401430 753907 Schuylkill River at Pottstown, Pa. 1902-2005 51 1,150 684 18.7 1.42 6.5501472157 C 400905 753606 French Creek near Phoenixville, Pa. 1969-2006 38 59.1 530 .62 1.32 1.7601472174 C 400522 753750 Pickering Creek near Chester Springs, Pa. 1967-1983 17 5.98 439 0 .28 7.2801472198 C 402338 753057 Perkiomen Creek at East Greenville, Pa. 1982-2005 24 38 623 3.35 1.42 2.9801472199 C 402226 753122 West Branch Perkiomen Creek at Hillegass, Pa. 1982-2005 24 23 685 4.76 1.20 2.4601472620 C 402414 751405 East Branch Perkiomen Creek near Dublin, Pa. 1984-2005 22 4.07 420 0 1.64 .3601473000 C 401346 752707 Perkiomen Creek at Graterford, Pa. 1915-2005 91 279 468 1.27 1.46 6.6701473100 P 401226 752157 Zacharias Creek near Skippack, Pa. 1960-1980 21 7.29 322 0 .06 9.65
22 Regression Equations for Estimating Flood Flows at Selected Recurrence Intervals Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued [C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis] U.S. Geological Survey streamflow- gaging station number Type Latitude (ddmmss) Longitude (ddmmss) Station name Period of record1 (water year)2 Number of years used in analysis3 Basin characteristics Drainage area (mi2

)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

01473120

C 400952 752601 Skippack Creek near Collegeville, Pa. 1966-1994 29 53.7 289 0 0.16 24.7

01473169

C 400445 752740 Valley Creek at Pa. Turnpike Br near Valley Forge, Pa. 1983-2005 23 20.8 356 66.9 .54 42.9

01473880 P 400813 751121 Pine Run Tributary at Fort Washington, Pa. 1962-1979 18 2.02 287 0 .19 62.901473900

C 400726 751313 Wissahickon Creek at Fort Washington, Pa. 1962-2006 25 40.5 302 7.66 .40 53.6

01473950

C 400450 751335 Wissahickon Cr at Bells Mill Rd, Phila., Pa. 1966-1981 16 53.6 285 19.1 .50 55.2

01474000

C 400445 751343 Wissahickon Creek at Mouth, Philadelphia, Pa. 1966-2005 40 64 284 16 .53 57.4

01475300

C 400121 752520 Darby Creek at Waterloo Mills near Devon, Pa. 1972-1999 26 5.1 435 0 .25 67.2

01475510

C 395544 751622 Darby Creek near Darby, Pa. 1964-1990 27 37.4 325 0 .33 75.1

01475530

C 395829 751649 Cobbs Cr at U.S. Hghwy No. 1 at Philadelphia, Pa. 1965-2005 18 4.78 319 0 .42 87.7

01475550

C 395502 751452 Cobbs Creek at Darby, Pa. 1964-1990 27 22 208 0 .30 87.4

01475850

C 395835 752613 Crum Creek near Newtown Square, Pa. 1977-2005 29 15.8 420 0 .34 30.7

01476480

C 395458 752413 Ridley Creek at Media, Pa. 1987-2005 18 30.2 374 0 .36 23.4

01476500

C 395410 752335 Ridley Creek at Moylan, Pa. 1932-1955 24 31.9 368 0 .37 26.6

01477000

C 395208 752431 Chester Creek near Chester, Pa. 1932-2006 75 61.1 339 0 .56 38.1

01478200

C 394654 754803 Middle Branch White Clay Creek near Landenberg, Pa. 1960-1995 32 12.7 452 4.89 .86 6.91

01479820

C 394900 754131 Red Clay Creek near Kennett Square, Pa. 1988-2005 18 28.3 371 11.1 1.24 17.6

01480300

C 400422 755140 West Branch Brandywine Creek near Honey Brook, Pa. 1960-2006 47 18.7 726 3.36 2.26 2.61

01480500

C 395908 754940 West Branch Brandywine Creek at Coatesville, Pa. 1942-2006 45 46.1 663 1.35 1.50 4.33

01480610 P 395820 755106 Sucker Run near Coatesville, Pa. 1964-2005 39 2.62 544 25 .08 21.401480617

C 395742 754806 West Branch Brandywine Creek at Modena, Pa. 1970-2006 37 55.3 633 5.34 1.27 10.5

01480800

C 400020 754220 East Branch Brandywine Creek at Downingtown, Pa. 1942-1968 11 81.6 531 6.72 2.03 9.03

01481000

C 395211 753537 Brandywine Creek at Chadds Ford, Pa. 1912-2006 87 287 490 7.63 1.06 11.7

01514000

C 420745 761615 Owego Creek near Owego, N.Y. 1930-1999 70 185 -- -- .28 --

01516350

C 414739 770450 Tioga River near Mansfield, Pa. 1972-2005 34 153 1,870 0 .24 1.45

01516500

C 414727 770054 Corey Creek near Mainesburg, Pa. 1955-2006 52 12.2 1,770 0 .32 .06

01516800 P 414919 770550 Manns Creek near Mansfield, Pa. 1960-1977 17 3.04 1,520 0 .01 001517000

C 414854 765755 Elk Run near Mainesburg, Pa. 1955-1978 24 10.2 1,810 0 .03 .02

01518000

C 415430 770747 Tioga River at Tioga, Pa. 1889-2005 39 282 1,770 0 .25 1.26

01518420 P 415033 771625 Crooked Cr bl Catlin Hollow at Middlebury Center, Pa. 1985-2005 20 74.4 1,710 0 .24 .3501518500

C 415408 770855 Crooked Creek at Tioga, Pa. 1954-1974 21 122 1,670 0 .39 .45

01518862

C 415523 773156 Cowanesque River at Westfield, Pa. 1984-2005 21 90.6 1,960 0 .26 .78

01519200 P 415915 771809 Cowanesque River at Elkland, Pa. 1980-2005 26 234 1,850 0 .13 .5101520000

C 415948 770825 Cowanesque River near Lawrenceville, Pa. 1952-2005 27 298 1,780 0 .15 .53

01526000

C 420400 771702 Tuscarora Creek near South Addison, N.Y. 1937-1972 46 114 -- 0 .21 0

01532000

C 414225 762906 Towanda Creek near Monroeton, Pa. 1914-2006 93 215 1,600 0 .49 .57
Appendix 1 23

Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued[C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis]

U.S. Geological 

Survey 

streamflowgaging station 

number

Type Latitude (ddmmss) Longitude (ddmmss) Station name

Period of 

record1

(water 

year)2

Number of 

years used 

in analysis3

Basin characteristics

Drainage 

area 

(mi2)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

01532200 P 413525 762560 South Branch Towanda Creek at New Albany, Pa. 1963-1995 30 13.4 1,560 0 0.25 0.0601532850 C 415145 760026 MB Wyalusing Creek near Birchardville, Pa. 1960-1979 20 5.67 1,480 0 .24 .0601533250 P 414225 760710 Tuscarora Creek near Silvara, Pa. 1963-1995 33 11.8 1,250 0 1.81 .1601533800 C 414810 753840 Butler Creek at Gibson, Pa. 1963-1979 15 7.51 1,600 0 2.40 .4301533950 C 413429 753832 SB Tunkhannock Creek near Montdale, Pa. 1961-1978 18 12.6 1,510 0 3.65 2.101534000 C 413330 755342 Tunkhannock Creek near Tunkhannock, Pa. 1914-2006 93 383 1,330 0 2.87 3.0601534500 C 413016 753233 Lackawanna River at Archbald, Pa. 1940-2005 20 108 1,730 0 2.82 7.0301536000 C 412133 754441 Lackawanna River at Old Forge, Pa. 1939-2005 21 335 1,540 0 3.04 17.501538000 C 410333 760538 Wapwallopen Creek near Wapwallopen, Pa. 1920-2006 87 43.8 1,380 0 4.33 11.101538800 P 411840 760850 Huntington Creek near Pikes Creek, Pa. 1960-1980 21 4.97 1,580 0 .11 .0601539000 C 410441 762553 Fishing Creek near Bloomsburg, Pa. 1936-2006 71 274 1,320 0 .67 .301539500 C 410450 763040 Little Fishing Creek at Eyers Grove, Pa. 1941-1958 18 56.5 1,080 0 .13 .6501540000 C 410010 762750 Fishing Creek at Bloomsburg, Pa. 1914-1931 18 355 1,230 .14 .56 .6601540200 C 405110 761648 Trexler Run near Ringtown, Pa. 1959-1979 21 1.77 1,440 0 .30 001541000 C 405349 784038 West Branch Susquehanna River at Bower, Pa. 1889-2005 92 315 1,720 0 .10 1.8301541200 C 405741 783110 WB Susquehanna River near Curwensville, Pa. 1956-1965 10 367 1,700 0 .42 1.6301541500 C 405818 782422 Clearfield Creek at Dimeling, Pa. 1914-2005 47 371 1,710 0 .87 1.4401542000 C 405058 781605 Moshannon Creek at Osceola Mills, Pa. 1936-1993 52 68.7 1,820 0 .07 2.5101542500 C 410703 780633 WB Susquehanna River at Karthaus, Pa. 1936-2005 21 1,460 1,710 0 .51 1.9301542720 P 411258 783460 Wilson Run at Penfield, Pa. 1962-1995 33 8.4 1,770 0 0 .0801542810 C 413444 781734 Waldy Run near Emporium, Pa. 1964-2005 42 5.24 1,850 0 0 001543000 C 412448 781150 Driftwood Br Sinnemahoning Cr at Sterling Run, Pa. 1914-2005 92 272 1,740 0 .12 .6201543500 C 411902 780612 Sinnemahoning Creek at Sinnemahoning, Pa. 1936-2005 70 685 1,720 0 .14 .4201543700 P 413108 780140 First Fork Sinnemahoning Creek at Wharton, Pa. 1984-2005 22 182 1,900 0 .22 .2701544450 P 413849 773922 Germania Branch at Germania, Pa. 1964-1979 11 2.39 2,150 0 .01 .0601544500 C 412833 774934 Kettle Creek at Cross Fork, Pa. 1936-2005 65 136 1,890 0 .32 .0501545600 C 412322 774128 Young Womans Creek near Renovo, Pa. 1965-2005 41 46.2 1,820 0 .01 .1101546000 C 405630 774740 North Bald Eagle Creek at Milesburg, Pa. 1911-1934 18 119 1,400 7.47 .32 .7201546400 C 405001 774940 Spring Creek at Houserville, Pa. 1985-2005 21 58.5 1,340 75.1 .13 11.101546500 C 405323 774740 Spring Creek near Axemann, Pa. 1936-2005 66 87.2 1,280 83.1 .11 11.501547100 C 405554 774713 Spring Creek at Milesburg, Pa. 1967-2005 39 142 1,260 78.3 .15 9.201547200 C 405635 774712 Bald Eagle Creek bl Spring Creek at Milesburg, Pa. 1956-2005 50 265 1,320 46 .22 5.4501547500 C 410306 773617 Bald Eagle Creek at Blanchard, Pa. 1955-2005 15 339 1,250 44.6 1.99 4.8901547700 C 410334 773622 Marsh Creek at Blanchard, Pa. 1956-2005 50 44.1 1,300 .35 .05 .5301547800 C 410126 775415 South Fork Beech Creek near Snow Shoe, Pa. 1959-1981 23 12.2 1,960 0 .01 2.6
24 Regression Equations for Estimating Flood Flows at Selected Recurrence Intervals Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued [C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis] U.S. Geological Survey streamflow- gaging station number Type Latitude (ddmmss) Longitude (ddmmss) Station name Period of record1 (water year)2 Number of years used in analysis3 Basin characteristics Drainage area (mi2

)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

01547950

C 410642 774209 Beech Creek at Monument, Pa. 1968-2005 38 152 1,670 0 0.08 0.72

01548005 P 410451 773259 Bald Eagle Creek near Beech Creek Station, Pa. 1911-2005 94 562 1,360 27.4 1.24 3.2401548020 P 410030 771935 Bull Run near Loganton, Pa. 1963-1981 19 1.92 1,810 .73 0 001548500

C 413118 772652 Pine Creek at Cedar Run, Pa. 1919-2005 87 604 1,880 0 .21 .45

01549000

C 411845 772245 Pine Creek near Waterville, Pa. 1909-1920 12 750 1,830 0 .22 .38

01549500

C 412825 771352 Blockhouse Creek near English Center, Pa. 1936-2005 65 37.7 1,770 0 .15 .81

01549700

C 411625 771928 Pine Creek bl L Pine Creek near Waterville, Pa. 1958-2005 48 944 1,790 0 .29 .38

01549780

C 412504 770946 Larrys Creek at Cogan House, Pa. 1960-1978 19 6.8 1,610 0 .03 .25

01550000

C 412506 770159 Lycoming Creek near Trout Run, Pa. 1914-2005 92 173 1,730 0 .16 .22

01550500 P 411601 770249 Lycoming Creek near Williamsport, Pa. 1988-2005 14 264 1,570 0 .20 .8401551000

C 411515 770040 Grafius Run at Williamsport, Pa. 1940-1953 14 3.03 908 0 .16 5.46

01552000

C 411930 765446 Loyalsock Creek at Loyalsockville, Pa. 1926-2005 80 435 1,670 0 .80 .33

01552100 P 412010 765745 Mill Creek near Warrensville, Pa. 1961-1978 18 11.9 1,380 0 5.30 .2201552500

C 412125 763206 Muncy Creek near Sonestown, Pa. 1936-2005 65 23.8 1,850 0 .21 .19

01553005 P 411227 764509 Muncy Creek near Muncy, Pa. 1989-2005 17 196 1,240 0 .43 .601553050 P 410705 770400 White Deer Hole Creek near Elimsport, Pa. 1961-1995 33 19.2 1,530 0 .29 001553130

C 410331 770437 Sand Spring Run near White Deer, Pa. 1968-1981 14 4.93 1,600 0 0 2.95

01553600

C 410457 763917 EB Chillisquaque Creek near Washingtonville, Pa. 1960-1978 19 9.48 799 0 .72 .07

01553700

C 410342 764050 Chillisquaque Creek at Washingtonville, Pa. 1980-2005 26 51.5 735 6.65 1.14 .23

01555000

C 405200 770255 Penns Creek at Penns Creek, Pa. 1930-2005 76 301 1,390 24 1.15 .6

01555500

C 403640 765444 East Mahantango Creek near Dalmatia, Pa. 1930-2005 76 162 915 0 .25 1.6

01555800 P 402235 782555 McDonald Run near East Freedom, Pa. 1959-1978 19 1.44 1,320 0 0 1.6401556000

C 402747 781200 Frankstown Br Juniata River at Williamsburg, Pa. 1889-2005 89 291 1,530 21 .31 7.55

01556400 P 403347 782035 Sandy Run near Bellwood, Pa. 1962-1981 20 5.93 1,610 9.15 0 19.201556500

C 403740 781738 Little Juniata River at Tipton, Pa. 1936-1981 36 93.7 1,730 5.13 .29 9.83

01557100

C 404000 781500 Schell Run at Tyrone, Pa. 1958-1981 23 1.71 1,500 0 0 4.92

01557500

C 404101 781402 Bald Eagle Creek at Tyrone, Pa. 1936-2005 66 44.1 1,630 5.04 .02 1.19

01558000

C 403645 780827 Little Juniata River at Spruce Creek, Pa. 1936-2005 67 220 1,570 20.5 .18 5.51

01559000

C 402905 780109 Juniata River at Huntingdon, Pa. 1896-2005 104 816 1,420 32.6 .25 4.43

01559500

C 403125 775815 Standing Stone Creek near Huntingdon, Pa. 1889-1958 29 128 1,210 5.11 .63 .09

01559700

C 395840 783708 Sulphur Springs Creek near Manns Choice, Pa. 1962-1978 17 5.28 1,690 1.73 .01 2.12

01559790 P 400245 783145 Raystown Branch Juniata River at Wolfsburg, Pa. 1989-2005 13 131 1,680 1.17 .75 1.1101560000

C 400418 782934 Dunning Creek at Belden, Pa. 1936-2005 70 172 1,590 4.27 .21 1.23

01561000

C 395720 781515 Brush Creek at Gapsville, Pa. 1930-1958 29 36.5 1,570 0 .14 1.16

01562000

C 401257 781556 Raystown Branch Juniata River at Saxton, Pa. 1889-2005 93 756 1,500 14.2 .27 1.71
Appendix 1 25

Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued[C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis]

U.S. Geological 

Survey 

streamflowgaging station 

number

Type Latitude (ddmmss) Longitude (ddmmss) Station name

Period of 

record1

(water 

year)2

Number of 

years used 

in analysis3

Basin characteristics

Drainage 

area 

(mi2)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

01562500 C 402100 780750 Great Trough Creek near Marklesburg, Pa. 1930-1957 28 84.6 1,490 0 0.31 0.501563000 C 402535 780147 Raystown Branch Juniata River near Huntingdon, Pa. 1936-1971 26 956 1,470 11.7 1.40 1.5101563800 P 400520 780255 Elders Branch near Hustontown, Pa. 1960-1978 19 3.44 1,170 0 .07 .0401564500 C 401245 775532 Aughwick Creek near Three Springs, Pa. 1939-2005 67 205 1,180 4.46 .44 .8201564512 P 401655 775327 Aughwick Creek near Shirleysburg, Pa. 1990-2005 16 296 1,170 7.03 .47 .7101565000 C 403917 773460 Kishacoquillas Creek at Reedsville, Pa. 1936-2005 51 164 1,220 24.8 .19 1.401565700 C 403620 771840 Little Lost Creek at Oakland Mills, Pa. 1960-1981 22 6.52 758 47.8 .50 1.7701565920 P 402115 773855 Lick Run near East Waterford, Pa. 1962-1981 20 8.34 1,020 9.09 .41 .201566000 C 403055 772510 Tuscarora Creek near Port Royal, Pa. 1889-2005 62 214 1,010 0 1.05 .101566500 C 403355 770705 Cocolamus Creek near Millerstown, Pa. 1930-1972 29 57.2 813 5.66 .73 .2101567500 C 402215 772409 Bixler Run near Loysville, Pa. 1954-2005 52 15 907 0 .91 .2301568000 C 401924 771009 Sherman Creek at Shermans Dale, Pa. 1927-2005 76 207 1,010 0 .98 .3701568500 C 402737 764506 Clark Creek near Carsonville, Pa. 1938-1996 59 22 1,050 0 4.62 .0501569340 P 400740 773250 Newburg Run at Newburg, Pa. 1964-1995 32 5.42 804 0 0 1.9501569800 C 401405 770823 Letort Spring Run near Carlisle, Pa. 1976-2005 30 21.6 498 99 .51 24.701570000 C 401508 770117 Conodoguinet Creek near Hogestown, Pa. 1912-2005 73 470 754 38.1 .85 3.9801571000 C 401830 765100 Paxton Creek near Penbrook, Pa. 1940-1998 35 11.2 457 30.1 .04 64.201571500 C 401329 765354 Yellow Breeches Creek near Camp Hill, Pa. 1910-2005 62 216 809 34.2 1.60 6.2201571820 C 403450 762418 Swatara Creek at Ravine, Pa. 1996-2006 10 43.9 1,140 0 .67 3.4101572000 C 403215 762240 Lower Little Swatara Creek at Pine Grove, Pa. 1920-1984 18 34.3 840 0 .33 .6701572025 C 403157 762409 Swatara Creek near Pine Grove, Pa. 1989-2005 16 116 938 0 .59 2.6701572190 C 402845 763152 Swatara Creek near Inwood, Pa. 1989-2005 17 161 919 0 .81 2.4601572900 P 402425 763315 Reeds Creek near Ono, Pa. 1962-1981 20 8.69 518 3.64 .29 9.5801573000 C 402409 763439 Swatara Creek at Harper Tavern, Pa. 1889-2005 87 337 754 1.32 1.05 2.9201573160 C 402034 763346 Quittapahilla Creek near Bellegrove, Pa. 1975-1993 19 74.2 527 75.6 .41 16.101573500 C 402350 764235 Manada Cr at Manada Gap, Pa. 1938-1958 21 13.5 803 0 .28 .8301573560 C 401754 764005 Swatara Creek near Hershey, Pa. 1975-2005 31 483 687 12.9 .92 4.9901574000 C 400456 764313 West Conewago Creek near Manchester, Pa. 1929-2005 77 510 625 6.17 1.45 3.2301574500 C 395243 765113 Codorus Creek at Spring Grove, Pa. 1930-2005 36 75.5 703 16.8 3.62 3.7401574800 C 394857 763759 EB Codorus Creek Tributary near Winterstown, Pa. 1960-1975 16 5.23 901 0 .37 .4701575000 C 395514 764457 South Branch Codorus Creek near York, Pa. 1928-1995 43 117 747 1.97 .90 2.9101576085 C 400841 755920 Little Conestoga Creek near Churchtown, Pa. 1982-1995 14 5.82 625 51 .01 1.3101576320 P 401244 760730 Stony Run at Reamstown, Pa. 1964-1995 31 3.56 523 10 .90 20.401576500 C 400300 761639 Conestoga River at Lancaster, Pa. 1929-2005 77 322 518 44.3 1.03 8.0201576754 C 395647 762205 Conestoga River at Conestoga, Pa. 1985-2005 20 470 479 59 .78 11.6
26 Regression Equations for Estimating Flood Flows at Selected Recurrence Intervals Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued [C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis] U.S. Geological Survey streamflow- gaging station number Type Latitude (ddmmss) Longitude (ddmmss) Station name Period of record1 (water year)2 Number of years used in analysis3 Basin characteristics Drainage area (mi2

)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

01577500

C 394621 761858 Muddy Creek at Castle Fin, Pa. 1929-1972 15 133 650 0.33 0.46 0.7

01578200 P 395035 761145 Conowingo Creek near Buck, Pa. 1963-2005 41 5.53 656 0 1.28 1.4601578400

C 395341 760650 Bowery Run near Quarryville, Pa. 1963-1981 19 5.98 655 25.4 .98 .02

01600700 P 395535 783940 Little Wills Creek at Bard, Pa. 1961-1981 21 10.3 1,830 0 .02 .0401601000

C 394843 784300 Wills Creek below Hyndman, Pa. 1952-2005 38 146 2,030 .96 .14 .33

01601500

C 394007 784718 Wills Creek near Cumberland, Md. 1930-1990 61 247 -- -- .03 --

01603500

C 394723 783848 Evitts Creek near Centerville, Pa. 1933-1982 50 30.2 1,620 21.8 .22 .2

01613050

C 395354 780757 Tonoloway Creek near Needmore, Pa. 1963-2005 41 10.7 1,240 0 .14 .91

01613500

C 394323 780338 Licking Creek near Sylvan, Pa. 1931-1941 11 158 1,040 16.2 .71 .72

01614090

C 395548 772623 Conococheague Creek near Fayetteville, Pa. 1961-1981 21 5.05 1,550 0 .55 0

01614500

C 394257 774928 Conococheague Creek at Fairview, Md. 1889-1990 64 494 -- 42 1.35 --

01638900 P 394745 771150 White Run near Gettysburg, Pa. 1961-1980 20 12.5 553 0 2.31 8.6403007800

C 414907 781735 Allegheny River at Port Allegany, Pa. 1975-2005 31 248 2,060 0 .09 .94

03008000

C 415340 782057 Newell Creek near Port Allegany, Pa. 1960-1978 19 7.79 1,840 0 0 .1

03009680

C 414835 782550 Potato Creek at Smethport, Pa. 1972-1997 24 160 1,980 0 .42 .8

03010500

C 415748 782311 Allegheny River at Eldred, Pa. 1916-2005 90 550 1,980 0 1.45 .86

03010655

C 415742 781154 Oswayo Creek at Shinglehouse, Pa. 1975-2005 31 98.7 2,030 0 .13 .22

03011020

C 420923 784256 Allegheny River at Salamanca, N.Y. 1904-1999 96 1,610 -- -- 1.04 0

03011800

C 414559 784308 Kinzua Creek near Guffey, Pa. 1966-2005 40 38.8 2,050 0 .64 1.09

03013000

C 421015 790410 Conewango Creek at Waterboro, N.Y. 1938-1994 56 290 -- -- 4.69 --

03015000

C 415617 790760 Conewango Creek at Russell, Pa. 1936-2005 70 816 1,520 0 6.45 2.57

03015080 P 415555 790538 Ackley Run near Russell, Pa. 1962-1981 20 9.65 1,900 0 0 .1603015280

C 415410 791418 Jackson Run near North Warren, Pa. 1963-1979 17 12.8 1,650 0 2.33 .9

03015390 P 415629 793841 Hare Creek near Corry, Pa. 1964-1985 19 13.6 1,630 0 3.41 .2603015500

C 415109 791903 Brokenstraw Creek at Youngsville, Pa. 1910-2005 96 321 1,600 0 2.96 1.08

03017500

C 413607 790301 Tionesta Creek at Lynch, Pa. 1938-1979 42 233 1,760 0 .11 1.29

03019000

C 412825 792305 Tionesta Creek at Nebraska, Pa. 1910-1940 19 469 1,690 0 .58 .82

03020440 P 414531 793408 WB Caldwell Creek near Grand Valley, Pa. 1964-1981 16 4.37 1,680 0 0 .0803020500

C 412854 794144 Oil Creek at Rouseville, Pa. 1910-2005 96 300 1,520 0 1.32 1.17

03021350

C 420055 794658 French Creek near Wattsburg, Pa. 1975-2005 31 92 1,600 0 2.48 .5

03021410

C 420454 795102 West Branch French Creek near Lowville, Pa. 1975-1994 20 52.3 1,470 0 5.25 1.12

03021700

C 415553 800502 Little Conneauttee Creek near McKean, Pa. 1961-1978 18 3.6 1,440 0 0 .01

03022500

C 414250 800850 French Creek at Saegerstown, Pa. 1913-1939 18 629 1,420 0 4.54 1.39

03022540

C 414126 800254 Woodcock Creek at Blooming Valley, Pa. 1975-2005 31 31.1 1,450 0 2.03 .18

03023000

C 414020 801255 Cussewago Creek near Meadville, Pa. 1911-1938 28 90.2 1,250 0 7.31 2.07
Appendix 1 27

Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued[C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis]

U.S. Geological 

Survey 

streamflowgaging station 

number

Type Latitude (ddmmss) Longitude (ddmmss) Station name

Period of 

record1

(water 

year)2

Number of 

years used 

in analysis3

Basin characteristics

Drainage 

area 

(mi2)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

03023500 C 412815 800105 French Creek at Carlton, Pa. 1909-1925 17 998 1,370 0 5.43 2.403024000 C 412615 795722 French Creek at Utica, Pa. 1913-2005 38 1,030 1,370 0 5.29 2.3303025000 C 412543 795248 Sugar Creek at Sugarcreek, Pa. 1933-1979 47 166 1,440 0 1.90 .3103025200 C 412520 795059 Patchel Run near Franklin, Pa. 1961-1978 18 5.67 1,400 0 0 .8103026400 P 411053 794125 Richey Run at Emlenton, Pa. 1963-1981 19 5.69 1,390 0 0 3.1803026500 C 413752 783437 Sevenmile Run near Rasselas, Pa. 1952-2005 54 7.84 2,070 0 0 .1603028000 C 413431 784133 West Branch Clarion River at Wilcox, Pa. 1955-2005 51 63 1,960 0 .18 1.1703029000 C 412515 784410 Clarion River at Ridgway, Pa. 1941-2004 12 303 1,910 0 .93 2.7103029200 P 411917 790439 Clear Creek near Sigel, Pa. 1960-1981 21 7.32 1,750 0 0 .0303029400 C 412016 791250 Toms Run at Cooksburg, Pa. 1960-1978 19 12.6 1,570 0 .17 103029500 C 411950 791233 Clarion River at Cooksburg, Pa. 1936-2005 67 807 1,780 0 .49 1.3803030500 C 411133 792625 Clarion River near Piney, Pa. 1936-2005 58 966 1,740 0 .41 1.4603031000 C 410857 793937 Clarion River at St. Petersburg, Pa. 1942-1953 12 1,240 1,660 0 .32 1.5803031780 P 411453 785008 Mill Creek near Brockway, Pa. 1965-1981 17 2.02 1,760 0 .12 .1203031950 C 405930 790526 Big Run nr Sprankle Mills, Pa. 1964-1981 18 7.38 1,510 0 0 .503032500 C 405940 792340 Redbank Creek at St. Charles, Pa. 1910-2005 96 528 1,560 0 .72 2.7903034000 C 405621 790031 Mahoning Creek at Punxsutawney, Pa. 1936-2005 70 158 1,580 0 .23 3.0303034500 C 405010 790637 Little Mahoning Creek at McCormick, Pa. 1940-2005 66 87.4 1,560 0 0 .3503035000 C 405405 791335 Mahoning Creek near Dayton, Pa. 1917-1940 24 321 1,530 0 1.03 1.7903038000 C 403917 792056 Crooked Creek at Idaho, Pa. 1936-2005 70 191 1,270 0 .81 1.2103039000 C 404313 793042 Crooked Creek at Crooked Creek Dam, Pa. 1910-1991 30 275 1,240 0 1.62 1.0903039200 C 400249 784958 Clear Run near Buckstown, Pa. 1961-1978 18 3.68 2,700 0 .25 .3603040000 C 401708 785515 Stonycreek River at Ferndale, Pa. 1914-2005 90 452 2,160 0 1.13 2.9403041000 P 402037 785307 Little Conemaugh River at East Conemaugh, Pa. 1936-2005 70 186 2,070 0 .92 5.2903041500 C 402509 790135 Conemaugh River at Seward, Pa. 1936-2005 70 727 2,090 0 .97 5.3503042000 C 402824 791101 Blacklick Creek at Josephine, Pa. 1952-2005 54 192 1,810 0 .19 2.0203042170 P 403631 790949 Stoney Run at Indiana, Pa. 1964-1977 13 4.51 1,340 0 0 67.103042200 C 403345 785644 Little Yellow Creek near Strongstown, Pa. 1961-1987 19 7.36 1,840 0 0 .1903042500 C 403102 791019 Two Lick Creek at Graceton, Pa. 1952-2005 17 171 1,530 0 .70 5.2703043000 C 402825 791215 Blacklick Creek at Black Lick, Pa. 1905-1951 47 390 1,650 0 .57 3.5403045000 C 401733 792027 Loyalhanna Creek at Kingston, Pa. 1940-2005 66 172 1,720 0 .25 2.1103045500 C 402340 792555 Loyalhanna Creek at New Alexandria, Pa. 1911-1940 19 265 1,550 0 1.08 4.903047500 C 403205 792755 Kiskiminetas River at Avonmore, Pa. 1884-1937 48 1,720 1,750 0 1.42 4.3303049000 C 404257 794159 Buffalo Creek near Freeport, Pa. 1941-2005 64 137 1,250 0 .05 1.7303049800 C 403113 795618 Little Pine Creek near Etna, Pa. 1963-2005 42 5.78 1,110 0 0 26
28 Regression Equations for Estimating Flood Flows at Selected Recurrence Intervals Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued [C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis] U.S. Geological Survey streamflow- gaging station number Type Latitude (ddmmss) Longitude (ddmmss) Station name Period of record1 (water year)2 Number of years used in analysis3 Basin characteristics Drainage area (mi2

)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

03062500

C 393745 795710 Deckers Creek at Morgantown, W.V. 1947-1997 51 63.2 1,770 -- -- --

03070420

C 394551 793514 Stony Fork Tributary near Gibbon Glade, Pa. 1978-1989 12 .92 1,870 0 0 0.19

03070500

C 393718 794218 Big Sandy Creek near Rockville, W.V. 1888-1997 110 200 2,070 -- -- --

03072000

C 394533 795815 Dunkard Creek at Shannopin, Pa. 1941-2005 65 229 1,220 0 .14 .66

03072590

C 394744 794747 Georges Creek at Smithfield, Pa. 1964-1978 15 16.3 1,390 0 .10 9.45

03072840

C 395951 800231 Tenmile Creek near Clarksville, Pa. 1969-1979 11 133 1,170 0 .06 3.29

03072880 P 395627 801721 Browns Creek near Nineveh, Pa. 1963-1995 33 17.7 1,250 0 .03 .2303073000

C 395523 800422 South Fork Tenmile Creek at Jefferson, Pa. 1932-1995 64 180 1,210 0 .06 2.26

03074300

C 395204 794140 Lick Run at Hopwood, Pa. 1959-1978 20 3.8 1,990 0 0 .8

03074500

C 395848 794552 Redstone Creek at Waltersburg, Pa. 1943-2005 63 73.7 1,280 0 .27 13.6

03078000

C 394208 190812 Casselman at Grantsville, Md. 1948-1990 43 62.5 -- -- 2.39 --

03078500

C 394334 790255 Big Piney Run near Salisbury, Pa. 1933-1970 38 24.5 2,560 .45 1.12 .78

03079000

C 395135 791340 Casselman River at Markleton, Pa. 1915-2005 91 382 2,360 .03 .81 2.09

03080000

C 394913 791918 Laurel Hill Creek at Ursina, Pa. 1914-2005 92 121 2,210 0 .65 .71

03082200

C 400059 792533 Poplar Run near Normalville, Pa. 1961-1978 18 9.27 1,940 0 0 .23

03082500

C 400103 793538 Youghiogheny River at Connellsville, Pa. 1860-1941 50 1,330 2,260 2 1.57 1.66

03083000

C 400618 793001 Green Lick Run at Green Lick Reservoir, Pa. 1929-1979 51 3.11 1,910 0 0 .06

03083500

C 401424 794824 Youghiogheny River at Sutersville, Pa. 1921-1941 21 1,710 2,020 1.54 1.27 3.56

03083600 P 401359 794906 Gillespie Run near Sutersville, Pa. 1959-1981 21 4.05 1,120 0 0 11.603084000

C 402701 794250 Abers Creek near Murrysville, Pa. 1949-1993 45 4.39 1,160 0 .13 45.1

03084500

C 402309 794555 Turtle Creek at Trafford, Pa. 1917-1955 38 55.9 1,120 0 .01 22.4

03085500

C 402402 800548 Chartiers Creek at Carnegie, Pa. 1916-2005 82 257 1,130 0 .52 26.4

03086100

C 403627 800949 Big Sewickley Creek near Ambridge, Pa. 1963-1978 16 15.6 1,090 0 0 13.8

03098700

C 410720 803808 Crab Creek at Youngstown, Ohio 1959-1982 24 14 1,060 -- 6.65 31.8

03100000

C 413045 802815 Shenango River near Turnersville, Pa. 1912-1922 11 152 1,090 0 22.61 5.56

03101000

C 412950 802755 Sugar Run at Pymatuning Dam, Pa. 1935-1955 21 8.59 1,120 0 .32 1.55

03102500

C 412519 802235 Little Shenango River at Greenville, Pa. 1914-2005 89 104 1,210 0 5.83 2.47

03102950

C 412634 803518 Pymatuning Creek at Kinsman, Ohio 1966-2001 36 96.7 1,030 -- 12.96 .32

03103000

C 411840 802840 Pymatuning Creek near Orangeville, Pa. 1914-1963 48 169 1,050 0 12.53 .65

03104000

C 411355 803035 Shenango River at Sharon, Pa. 1912-1938 21 608 1,100 0 11.86 4.6

03104500

C 410000 802105 Shenango River at New Castle, Pa. 1913-1933 20 798 1,090 0 10.27 7.11

03104760

C 411110 801938 Harthegig Run near Greenfield, Pa. 1969-1980 12 2.26 1,260 0 4.12 2.08

03106000

C 404901 801433 Connoquenessing Creek near Zelienople, Pa. 1916-2005 90 356 1,190 0 .35 10

03106500

C 405302 801402 Slippery Rock Creek at Wurtemburg, Pa. 1912-1968 56 398 1,310 0 4.02 2.53

03108000

C 403740 802016 Raccoon Creek at Moffatts Mill, Pa. 1916-2005 90 178 1,110 0 .54 8.55
Appendix 1 29

Appendix 1. Streamflow-gaging stations and basin characteristics used in development of flood-flow regression equations for Pennsylvania streams.—Continued[C, continuous-record station; P, partial-record station; ddmmss, degrees, minutes, seconds; mi2, square miles; ft, feet; --, not used in regression analysis]

U.S. Geological 

Survey 

streamflowgaging station 

number

Type Latitude (ddmmss) Longitude (ddmmss) Station name

Period of 

record1

(water 

year)2

Number of 

years used 

in analysis3

Basin characteristics

Drainage 

area 

(mi2)

Mean 

elevation 

(ft)

Percent 

carbonate 

bedrock

Percent 

storage

Percent 

urban 

area

03109000 C 404655 804533 Lisbon Creek at Lisbon, Ohio 1947-1981 35 6.19 1,180 -- 0.40 1.8503109500 C 404033 803227 Little Beaver Creek near East Liverpool, Ohio 1916-2001 86 496 1,140 -- .42 3.64

03111150 C 401154 802428 Brush Run near Buffalo, Pa. 1961-1985 21 10.3 1,190 0 0 1.11

04213000 C 415537 803615 Conneaut Creek at Conneaut, Ohio 1923-2001 66 175 1,010 -- 2.73 1.7604213040 C 415642 802651 Raccoon Creek near West Springfield, Pa. 1961-1995 34 2.6 821 0 6.01 3.6104213075 C 415931 801729 Brandy Run near Girard, Pa. 1987-2005 19 4.45 898 0 .22 9.104213200 P 420554 800435 Mill Creek at Erie, Pa. 1964-2005 42 9.16 1,050 0 0 35.2

1Period of record may include historical peaks, periods of flow regulation, and breaks in systematic period of record. 2Water year is defined as a 12-month period beginning October 1 and ending September 30. The water year is designated by the calendar year in which it ends.3Number of years used in analysis primarily consists of the systematic period of record and may include historic peak year. Breaks in systematic period of record and flow-regulated years are not included. 
30 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01424500 1 Observed 2,120 2,950 3,520 4,880 5,500 7,040

Predicted 1,780 2,990 3,960 6,570 7,890 11,500

Weighted 2,080 2,960 3,640 5,480 6,380 8,730

01426000 1 Observed 2,780 4,070 5,000 7,220 8,240 10,800

Predicted 2,580 4,310 5,680 9,300 11,100 16,000

Weighted 2,760 4,110 5,130 7,770 9,030 12,300

01428750 1 Observed 2,050 3,690 5,310 11,100 14,900 28,500

Predicted 1,560 2,640 3,500 5,800 6,960 10,100

Weighted 2,010 3,520 4,930 9,630 12,600 22,900

01429000 1 Observed 2,810 3,960 4,820 6,990 8,030 10,800

Predicted 1,920 3,220 4,280 7,120 8,570 12,600

Weighted 2,660 3,760 4,630 7,040 8,270 11,600

01429300 1 Observed 2,020 3,100 3,960 6,340 7,580 11,100

Predicted 1,720 2,900 3,840 6,360 7,630 11,100

Weighted 1,990 3,060 3,940 6,350 7,590 11,100

01429500 1 Observed 3,460 6,090 8,540 16,600 21,500 37,500

Predicted 2,190 3,670 4,850 8,030 9,640 14,100

Weighted 3,250 5,420 7,250 12,800 16,100 26,600

01430000 1 Observed 6,710 10,100 12,900 20,700 25,000 37,200

Predicted 4,690 7,670 10,100 16,600 19,800 28,900

Weighted 6,260 9,230 11,700 18,500 22,200 32,600

01430500 1 Observed 5,770 8,790 11,200 18,000 21,500 31,600

Predicted 5,590 9,110 11,900 19,500 23,400 34,000

Weighted 5,740 8,870 11,500 18,700 22,300 32,700

01431000 1 Observed 2,430 4,030 5,310 8,760 10,500 15,400

Predicted 2,330 3,870 5,130 8,550 10,300 15,100

Weighted 2,420 4,010 5,270 8,710 10,500 15,300

01431500 1 Observed 8,420 14,200 19,500 36,800 47,100 81,000

Predicted 7,600 12,300 16,100 26,200 31,300 45,500

Weighted 8,380 14,000 19,000 34,700 43,900 73,400

01431680 1 Observed 226 314 377 532 605 794

Predicted 234 415 562 960 1,160 1,730

Weighted 227 337 432 697 828 1,180

01438300 1 Observed 166 258 331 528 628 908

Predicted 274 485 655 1,110 1,330 1,960

Weighted 173 285 383 654 790 1,160

01439500 1 Observed 1,980 3,260 4,430 8,240 10,500 18,000

Predicted 2,940 4,850 6,430 10,800 13,000 19,200

Weighted 2,010 3,350 4,590 8,520 10,800 18,200
Appendix 2 31

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01440300 1 Observed 370 682 943 1,680 2,070 3,160

Predicted 304 536 723 1,220 1,480 2,170

Weighted 366 665 909 1,580 1,940 2,930

01440400 1 Observed 2,910 5,190 7,070 12,300 15,100 22,800

Predicted 2,120 3,540 4,690 7,790 9,360 13,700

Weighted 2,860 5,000 6,720 11,400 13,900 20,800

01441000 1 Observed 1,520 2,190 2,670 3,770 4,260 5,480

Predicted 2,230 3,730 4,940 8,160 9,790 14,300

Weighted 1,590 2,470 3,200 5,120 6,050 8,410

01442500 1 Observed 8,900 15,700 22,100 43,400 56,300 99,300

Predicted 7,180 11,600 15,200 24,800 29,600 42,900

Weighted 8,810 15,300 21,200 40,000 51,200 88,000

01446600 1 Observed 459 811 1,130 2,120 2,700 4,520

Predicted 401 699 945 1,620 1,960 2,920

Weighted 453 790 1,080 1,960 2,450 3,960

01447500 1 Observed 2,410 4,820 7,230 15,900 21,500 41,100

Predicted 2,240 3,720 4,950 8,350 10,100 15,100

Weighted 2,400 4,730 6,970 14,700 19,600 36,500

01447680 1 Observed 346 530 670 1,020 1,200 1,650

Predicted 528 906 1,230 2,130 2,610 3,970

Weighted 360 580 768 1,290 1,550 2,250

01447720 1 Observed 3,130 5,750 7,960 14,200 17,500 26,900

Predicted 2,570 4,240 5,640 9,560 11,600 17,400

Weighted 3,090 5,570 7,590 13,200 16,200 24,700

01448000 1 Observed 6,500 11,800 17,100 35,300 47,000 87,600

Predicted 6,700 10,800 14,200 23,600 28,400 42,000

Weighted 6,510 11,700 16,600 32,800 42,700 76,800

01448500 1 Observed 137 249 345 626 779 1,230

Predicted 121 217 297 514 625 936

Weighted 136 246 339 606 750 1,170

01449000 1 Observed 11,800 17,600 21,900 32,400 37,400 50,300

Predicted 12,700 20,100 26,200 42,800 51,200 74,800

Weighted 11,900 18,100 23,000 35,900 42,200 59,100

01449360 1 Observed 1,080 1,600 1,950 2,740 3,090 3,910

Predicted 1,870 3,140 4,160 6,870 8,240 12,000

Weighted 1,140 1,800 2,340 3,720 4,370 6,000

01449500 1 Observed 536 1,090 1,620 3,390 4,470 7,990

Predicted 639 1,100 1,480 2,500 3,020 4,480

Weighted 552 1,090 1,570 3,030 3,850 6,460
32 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01450000 1 Observed 1,790 2,910 3,780 6,080 7,220 10,300

Predicted 3,400 5,620 7,410 12,200 14,600 21,300

Weighted 1,960 3,380 4,610 7,920 9,550 13,900

01450500 1 Observed 2,270 3,910 5,310 9,450 11,700 18,500

Predicted 2,780 4,630 6,100 10,000 12,000 17,300

Weighted 2,290 3,970 5,400 9,540 11,800 18,300

01451000 1 Observed 21,800 36,400 49,000 87,400 109,000 176,000

Predicted 19,200 30,200 39,200 63,300 75,500 109,000

Weighted 21,300 34,500 45,300 76,000 92,700 143,000

01451500 1 Observed 1,550 3,610 5,730 13,300 18,200 34,500

Predicted 2,990 4,970 6,540 10,700 12,800 18,400

Weighted 1,620 3,730 5,830 12,900 17,200 31,500

01451650 1 Observed 2,190 4,790 7,460 17,300 23,800 46,500

Predicted 3,520 5,830 7,660 12,500 14,900 21,500

Weighted 2,380 5,030 7,520 15,500 20,200 36,200

01451800 1 Observed 2,310 3,880 5,110 8,340 9,940 14,200

Predicted 2,110 3,550 4,680 7,680 9,180 13,300

Weighted 2,300 3,840 5,040 8,180 9,750 14,000

01452000 1 Observed 2,930 5,230 7,210 13,000 16,200 25,500

Predicted 2,870 4,780 6,290 10,300 12,300 17,700

Weighted 2,930 5,190 7,100 12,600 15,500 24,000

01452300 1 Observed 270 508 707 1,270 1,560 2,370

Predicted 290 513 692 1,170 1,410 2,080

Weighted 273 509 702 1,230 1,500 2,250

01452500 1 Observed 596 1,250 1,920 4,440 6,120 12,200

Predicted 1,770 2,980 3,940 6,500 7,780 11,300

Weighted 654 1,400 2,160 4,780 6,410 12,000

01453000 1 Observed 22,100 37,100 49,900 88,000 109,000 172,000

Predicted 27,600 43,100 55,600 89,100 106,000 152,000

Weighted 22,400 37,700 50,700 88,200 108,000 168,000

01454600 1 Observed 111 212 313 670 900 1,700

Predicted 106 192 262 449 544 805

Weighted 110 207 296 579 748 1,312

01459500 1 Observed 6,480 9,600 12,000 18,100 21,000 29,000

Predicted 2,980 4,930 6,510 10,800 12,900 18,900

Weighted 6,210 8,960 11,000 16,200 18,900 26,300

01465500 2 Observed 10,800 17,100 22,300 36,800 44,500 66,400

Predicted 8,210 12,600 16,200 25,400 29,900 42,000

Weighted 10,700 16,900 21,800 35,100 42,000 61,900
Appendix 2 33

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01465770 2 Observed 744 1,060 1,320 2,040 2,430 3,520

Predicted 875 1,320 1,660 2,530 2,940 3,990

Weighted 758 1,120 1,420 2,260 2,670 3,750

01465785 2 Observed 667 925 1,110 1,590 1,820 2,430

Predicted 438 717 940 1,520 1,800 2,570

Weighted 639 876 1,060 1,560 1,810 2,510

01465790 2 Observed 812 1,150 1,420 2,110 2,450 3,390

Predicted 825 1,310 1,690 2,680 3,150 4,410

Weighted 814 1,190 1,510 2,390 2,820 3,960

01465798 2 Observed 3,110 4,580 5,680 8,490 9,850 13,500

Predicted 2,260 3,350 4,200 6,350 7,370 9,980

Weighted 3,070 4,460 5,470 7,970 9,190 12,500

01467042 2 Observed 2,600 3,570 4,270 5,940 6,720 8,700

Predicted 3,290 4,810 6,000 9,000 10,400 14,000

Weighted 2,670 3,830 4,770 7,270 8,440 11,300

01467043 2 Observed 280 471 622 1,030 1,230 1,790

Predicted 586 903 1,150 1,770 2,070 2,840

Weighted 314 564 783 1,360 1,640 2,320

01467048 2 Observed 3,690 5,730 7,380 12,000 14,400 21,400

Predicted 4,030 5,830 7,220 10,700 12,400 16,600

Weighted 3,710 5,740 7,360 11,700 13,900 20,000

01467050 2 Observed 879 1,320 1,660 2,570 3,030 4,320

Predicted 594 959 1,250 2,000 2,370 3,340

Weighted 849 1,240 1,540 2,320 2,720 3,840

01467086 2 Observed 2,370 3,380 4,070 5,670 6,380 8,100

Predicted 2,010 2,950 3,670 5,510 6,360 8,550

Weighted 2,340 3,300 3,970 5,610 6,370 8,300

01467087 2 Observed 6,270 8,730 10,400 14,300 16,000 20,200

Predicted 3,090 4,430 5,460 8,050 9,250 12,300

Weighted 6,030 8,060 9,290 12,100 13,400 17,000

01467089 2 Observed 6,650 8,470 9,670 12,300 13,400 16,100

Predicted 3,340 4,770 5,860 8,610 9,880 13,100

Weighted 6,280 7,680 8,510 10,600 11,700 14,600

01468500 1 Observed 3,370 5,470 7,230 12,300 15,100 23,100

Predicted 4,430 7,280 9,550 15,600 18,600 26,800

Weighted 3,450 5,700 7,620 13,100 15,900 24,100

01469500 1 Observed 1,390 2,410 3,190 5,160 6,090 8,480

Predicted 1,600 2,690 3,570 5,920 7,110 10,400

Weighted 1,400 2,430 3,230 5,260 6,230 8,740
34 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01470500 1 Observed 11,500 18,500 23,800 37,100 43,500 60,300

Predicted 10,300 16,500 21,500 34,600 41,100 59,100

Weighted 11,500 18,300 23,500 36,700 43,100 60,000

01470720 1 Observed 465 909 1,320 2,600 3,340 5,640

Predicted 391 686 922 1,550 1,860 2,730

Weighted 454 853 1,190 2,170 2,710 4,370

01470756 1 Observed 4,760 7,420 9,660 16,300 19,900 30,900

Predicted 5,350 8,750 11,400 18,600 22,100 31,800

Weighted 4,840 7,700 10,100 17,100 20,700 31,200

01470779 1 Observed 1,950 3,850 5,520 10,500 13,200 21,100

Predicted 2,530 4,230 5,570 9,130 10,900 15,800

Weighted 2,000 3,900 5,530 10,100 12,500 19,500

01470853 1 Observed 210 403 558 972 1,170 1,710

Predicted 307 542 731 1,230 1,480 2,180

Weighted 222 432 605 1,060 1,290 1,880

01470960 1 Observed 4,090 7,760 11,000 21,100 26,800 43,900

Predicted 5,530 9,030 11,800 19,200 22,900 33,100

Weighted 4,360 8,150 11,300 20,200 24,900 38,500

01471000 1 Observed 4,920 7,400 9,340 14,600 17,200 24,600

Predicted 6,560 10,700 13,900 22,600 26,900 38,800

Weighted 5,090 7,980 10,400 17,000 20,400 29,300

01471510 1 Observed 19,400 28,900 36,400 56,600 66,900 95,600

Predicted 22,700 35,700 46,000 73,300 86,900 124,000

Weighted 19,700 30,100 38,600 61,700 73,200 105,000

01471875 2 Observed 2,680 3,620 4,290 5,880 6,610 8,460

Predicted 2,410 4,020 5,320 8,830 10,600 15,600

Weighted 2,640 3,730 4,650 7,360 8,750 12,400

01471980 2 Observed 3,430 5,120 6,320 9,180 10,500 13,700

Predicted 3,250 5,360 7,050 11,600 13,900 20,300

Weighted 3,420 5,150 6,450 9,880 11,600 16,000

01472000 2 Observed 20,700 31,700 40,300 63,300 75,000 107,000

Predicted 21,300 32,000 40,400 62,700 73,600 103,000

Weighted 20,800 31,800 40,400 63,200 74,700 106,000

01472157 2 Observed 2,480 4,550 6,410 12,200 15,400 25,500

Predicted 2,790 4,850 6,570 11,300 13,800 20,800

Weighted 2,490 4,580 6,440 12,000 15,000 24,100

01472174 2 Observed 640 1,310 1,930 3,820 4,890 8,080

Predicted 593 1,100 1,530 2,730 3,360 5,190

Weighted 635 1,270 1,810 3,350 4,180 6,660
Appendix 2 35

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01472198 2 Observed 2,690 4,500 5,880 9,420 11,100 15,600

Predicted 2,040 3,580 4,860 8,400 10,200 15,400

Weighted 2,640 4,360 5,650 9,060 10,800 15,500

01472199 2 Observed 1,450 2,130 2,580 3,620 4,060 5,120

Predicted 1,420 2,530 3,470 6,050 7,400 11,200

Weighted 1,450 2,190 2,780 4,480 5,340 7,610

01472620 2 Observed 875 1,420 1,840 2,870 3,360 4,610

Predicted 427 818 1,160 2,130 2,650 4,180

Weighted 838 1,320 1,670 2,590 3,070 4,430

01473000 2 Observed 15,000 23,200 28,800 41,100 46,200 58,200

Predicted 8,570 13,900 18,200 29,900 35,800 52,000

Weighted 14,900 22,800 28,000 39,700 44,800 57,200

01473100 2 Observed 2,080 3,690 5,110 9,410 11,800 19,200

Predicted 695 1,270 1,750 3,100 3,800 5,830

Weighted 1,960 3,270 4,270 6,990 8,500 13,300

01473120 2 Observed 5,760 9,450 12,900 24,400 31,500 55,300

Predicted 3,150 5,120 6,720 11,000 13,100 18,900

Weighted 5,590 8,880 11,700 20,200 25,300 42,100

01473169 2 Observed 1,250 2,060 2,770 4,960 6,210 10,100

Predicted 1,440 2,100 2,600 3,840 4,430 5,970

Weighted 1,270 2,060 2,730 4,550 5,510 8,400

01473880 2 Observed 239 372 473 732 858 1,190

Predicted 407 674 889 1,450 1,730 2,470

Weighted 256 431 590 1,030 1,250 1,800

01473900 2 Observed 3,320 5,120 6,690 11,400 14,100 22,400

Predicted 3,020 4,540 5,740 8,790 10,300 14,100

Weighted 3,290 5,040 6,480 10,500 12,700 19,100

01473950 2 Observed 3,180 4,400 5,300 7,550 8,620 11,400

Predicted 3,530 5,160 6,400 9,570 11,100 14,900

Weighted 3,220 4,560 5,640 8,460 9,800 13,200

01474000 2 Observed 3,700 5,910 7,940 14,600 18,500 31,700

Predicted 4,100 5,950 7,370 11,000 12,700 17,000

Weighted 3,720 5,910 7,850 13,700 16,900 27,400

01475300 2 Observed 675 1,090 1,420 2,250 2,660 3,750

Predicted 796 1,270 1,640 2,600 3,060 4,300

Weighted 684 1,120 1,460 2,370 2,810 3,960

01475510 2 Observed 2,880 4,050 4,880 6,850 7,740 9,990

Predicted 3,330 4,870 6,070 9,090 10,500 14,100

Weighted 2,910 4,170 5,130 7,580 8,730 11,600
36 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01475530 2 Observed 813 1,550 2,270 4,740 6,280 11,500

Predicted 845 1,290 1,640 2,530 2,940 4,030

Weighted 816 1,500 2,090 3,810 4,770 7,930

01475550 2 Observed 2,480 3,530 4,270 6,030 6,840 8,850

Predicted 2,450 3,560 4,420 6,570 7,570 10,100

Weighted 2,470 3,530 4,300 6,210 7,100 9,330

01475850 2 Observed 1,150 1,930 2,590 4,470 5,480 8,400

Predicted 1,400 2,330 3,100 5,130 6,150 8,950

Weighted 1,160 1,990 2,690 4,680 5,710 8,600

01476480 2 Observed 1,480 3,060 4,660 10,400 14,200 27,200

Predicted 2,090 3,480 4,610 7,660 9,180 13,400

Weighted 1,540 3,150 4,650 9,260 11,900 20,600

01476500 2 Observed 1,190 2,110 3,010 6,100 8,050 14,800

Predicted 2,220 3,660 4,820 7,940 9,490 13,800

Weighted 1,270 2,350 3,420 6,750 8,600 14,400

01477000 2 Observed 2,990 5,330 7,480 14,500 18,700 32,400

Predicted 3,780 5,910 7,600 12,000 14,200 20,000

Weighted 3,010 5,360 7,490 14,100 18,000 30,100

01478200 2 Observed 970 1,670 2,260 4,000 4,940 7,730

Predicted 977 1,750 2,390 4,190 5,120 7,770

Weighted 970 1,680 2,290 4,050 5,000 7,750

01479820 2 Observed 1,950 4,210 6,710 16,900 24,300 53,400

Predicted 1,810 3,020 4,000 6,630 7,950 11,600

Weighted 1,930 3,980 5,950 12,600 16,900 33,400

01480300 2 Observed 1,230 2,200 3,030 5,430 6,730 10,500

Predicted 1,240 2,230 3,060 5,380 6,590 10,100

Weighted 1,230 2,200 3,030 5,420 6,700 10,400

01480500 2 Observed 1,910 3,450 4,800 8,880 11,200 18,000

Predicted 2,390 4,150 5,620 9,660 11,700 17,600

Weighted 1,930 3,510 4,910 9,050 11,300 17,900

01480610 2 Observed 331 588 802 1,410 1,730 2,650

Predicted 336 587 792 1,350 1,630 2,420

Weighted 331 588 800 1,390 1,700 2,580

01480617 2 Observed 2,590 4,620 6,300 11,000 13,500 20,400

Predicted 2,810 4,720 6,280 10,500 12,700 18,700

Weighted 2,600 4,630 6,300 10,900 13,200 19,900

01480800 2 Observed 3,560 4,240 4,710 5,770 6,240 7,390

Predicted 3,620 6,010 7,960 13,200 15,900 23,300

Weighted 3,570 4,740 5,980 9,830 11,800 16,900
Appendix 2 37

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01481000 2 Observed 7,010 11,100 14,400 23,100 27,600 40,000

Predicted 8,860 14,000 18,100 29,000 34,400 49,100

Weighted 7,050 11,200 14,600 23,900 28,600 41,500

01514000 1 Observed 5,950 8,980 11,300 17,500 20,500 28,500

Predicted 6,240 10,200 13,300 21,500 25,500 36,600

Weighted 5,960 9,080 11,500 18,100 21,300 29,800

01516350 1 Observed 7,130 13,100 18,700 36,600 47,300 81,500

Predicted 5,310 8,700 11,400 18,400 21,900 31,400

Weighted 6,9890 12,500 17,200 31,700 40,100 86,900

01516500 1 Observed 810 1,480 2,090 4,050 5,200 8,850

Predicted 595 1,030 1,380 2,310 2,770 4,040

Weighted 797 1,430 1,990 3,710 4,700 7,840

01516800 1 Observed 318 463 563 793 895 1,140

Predicted 172 308 419 714 863 1,270

Weighted 295 422 515 759 881 1,200

01517000 1 Observed 597 1,030 1,440 2,740 3,520 6,040

Predicted 517 900 1,210 2,020 2,420 3,530

Weighted 588 1,010 1,380 2,490 3,130 5,120

01518000 1 Observed 10,200 18,400 25,800 49,100 62,700 105,000

Predicted 9,000 14,500 18,900 30,400 36,100 51,600

Weighted 10,100 17,900 24,500 44,600 55,900 91,300

01518420 1 Observed 4,530 7,530 10,000 17,200 21,000 32,200

Predicted 2,850 4,740 6,240 10,200 12,200 17,500

Weighted 4,300 6,880 8,900 14,500 17,500 26,200

01518500 1 Observed 3,760 6,300 8,560 15,600 19,700 32,700

Predicted 4,330 7,140 9,350 15,200 18,100 26,000

Weighted 3,840 6,490 8,790 15,500 19,100 30,000

01518862 1 Observed 4,230 7,250 9,500 15,000 17,500 23,800

Predicted 3,370 5,590 7,350 12,000 14,300 20,600

Weighted 4,110 6,880 8,880 13,900 16,200 22,500

01519200 1 Observed 9,970 15,600 19,700 30,100 35,000 47,700

Predicted 7,710 12,500 16,300 26,200 31,200 44,600

Weighted 9,720 15,000 18,900 28,800 33,700 46,600

01520000 1 Observed 10,600 17,900 24,100 42,600 52,800 83,400

Predicted 9,480 15,300 19,900 31,900 37,900 54,100

Weighted 10,500 17,400 23,100 39,200 47,800 73,400

01526000 1 Observed 6,340 10,200 12,900 19,200 22,000 28,500

Predicted 4,120 6,800 8,910 14,500 17,300 24,800

Weighted 6,190 9,800 12,300 18,200 20,900 27,600
38 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01532000 1 Observed 9,890 17,500 24,300 45,000 56,800 92,900

Predicted 7,040 11,400 14,900 24,100 28,600 41,100

Weighted 9,790 17,200 23,500 42,500 53,200 86,200

01532200 1 Observed 642 1,030 1,360 2,390 2,960 4,740

Predicted 648 1,120 1,500 2,500 3,000 4,380

Weighted 643 1,040 1,390 2,420 2,970 4,620

01532850 1 Observed 410 748 1,020 1,770 2,150 3,190

Predicted 308 544 733 1,240 1,490 2,180

Weighted 396 700 936 1,570 1,890 2,770

01533250 1 Observed 470 799 1,060 1,720 2,050 2,910

Predicted 539 936 1,260 2,110 2,540 3,730

Weighted 476 820 1,100 1,830 2,190 3,150

01533800 1 Observed 421 779 1,120 2,270 2,980 5,350

Predicted 357 627 845 1,430 1,730 2,550

Weighted 410 735 1,020 1,890 2,390 4,000

01533950 1 Observed 770 1,210 1,530 2,320 2,700 3,660

Predicted 533 924 1,240 2,100 2,530 3,740

Weighted 734 1,130 1,440 2,230 2,630 3,690

01534000 1 Observed 13,200 20,100 24,800 35,500 40,100 50,900

Predicted 10,500 16,800 21,900 35,400 42,100 60,700

Weighted 13,100 19,900 24,600 35,500 40,300 52,200

01534500 1 Observed 3,240 4,690 5,840 9,000 10,600 15,300

Predicted 3,520 5,810 7,650 12,500 15,000 21,800

Weighted 3,280 4,950 6,380 10,400 12,400 18,000

01536000 1 Observed 8,260 12,500 16,100 26,700 32,500 49,700

Predicted 9,290 15,000 19,500 31,500 37,600 54,300

Weighted 8,400 13,100 17,100 28,500 34,500 51,500

01538000 1 Observed 1,210 2,000 2,620 4,300 5,160 7,500

Predicted 1,530 2,570 3,420 5,700 6,860 10,100

Weighted 1,220 2,030 2,690 4,480 5,380 7,860

01538800 1 Observed 425 762 1,030 1,760 2,130 3,110

Predicted 277 490 661 1,120 1,340 1,970

Weighted 405 701 925 1,520 1,820 2,660

01539000 1 Observed 8,630 14,300 18,900 31,400 37,800 55,700

Predicted 8,610 13,900 18,100 29,200 34,700 49,600

Weighted 8,630 14,300 18,800 31,100 37,300 54,700

01539500 1 Observed 2,070 2,720 3,150 4,100 4,510 5,470

Predicted 2,260 3,780 4,990 8,170 9,760 14,100

Weighted 2,100 2,990 3,740 5,770 6,740 9,230
Appendix 2 39

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01540000 1 Observed 11,400 17,900 22,400 33,000 37,800 49,300

Predicted 10,800 17,400 22,600 36,200 43,000 61,500

Weighted 11,400 17,800 22,500 34,300 40,000 54,600

01540200 1 Observed 52 118 189 457 638 1,290

Predicted 112 204 277 474 574 847

Weighted 60 137 215 464 613 1,110

01541000 3 Observed 7,800 11,400 14,200 21,500 25,200 35,300

Predicted 7,280 11,000 13,700 20,000 22,900 30,300

Weighted 7,780 11,400 14,100 21,300 24,900 34,800

01541200 3 Observed 9,460 12,600 14,600 18,800 20,500 24,300

Predicted 8,100 12,100 15,000 21,800 24,900 32,700

Weighted 9,160 12,500 14,800 20,300 22,800 28,700

01541500 3 Observed 7,820 11,100 13,500 19,200 21,800 28,600

Predicted 7,900 11,800 14,500 20,900 23,800 31,100

Weighted 7,820 11,200 13,600 19,500 22,200 29,000

01542000 3 Observed 1,270 1,930 2,430 3,670 4,270 5,850

Predicted 2,040 3,200 4,050 6,120 7,070 9,550

Weighted 1,310 2,050 2,630 4,090 4,760 6,490

01542500 3 Observed 27,700 38,500 45,600 61,100 67,600 83,000

Predicted 25,000 36,100 43,800 61,400 69,300 89,100

Weighted 27,400 38,000 45,100 61,200 68,200 85,000

01542720 3 Observed 239 329 391 538 605 772

Predicted 369 613 802 1,270 1,500 2,090

Weighted 249 368 466 717 829 1,100

01542810 3 Observed 192 301 390 643 777 1,170

Predicted 245 412 542 867 1,020 1,440

Weighted 195 313 413 688 828 1,220

01543000 3 Observed 8,150 13,600 18,200 31,400 38,500 59,300

Predicted 6,410 9,720 12,100 17,700 20,300 26,900

Weighted 8,100 13,400 17,700 30,000 36,500 55,800

01543500 3 Observed 17,000 27,100 35,400 58,900 71,200 107,000

Predicted 13,800 20,400 25,100 36,000 40,900 53,400

Weighted 16,900 26,700 34,500 55,800 67,100 99,600

01543700 3 Observed 4,560 6,960 8,830 13,900 16,400 23,400

Predicted 4,390 6,680 8,340 12,200 14,000 18,600

Weighted 4,540 6,900 8,710 13,300 15,600 21,800

01544450 3 Observed 100 140 167 234 264 340

Predicted 109 181 235 372 436 606

Weighted 102 153 194 301 350 473
40 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01544500 3 Observed 3,520 5,790 7,700 13,300 16,300 25,300

Predicted 3,440 5,270 6,590 9,730 11,200 14,800

Weighted 3,510 5,750 7,590 12,800 15,600 23,800

01545600 3 Observed 889 1,660 2,370 4,760 6,200 10,900

Predicted 1,480 2,340 2,990 4,560 5,290 7,190

Weighted 927 1,730 2,470 4,720 6,000 10,100

01546000 3 Observed 6,930 10,400 13,000 20,200 23,800 33,700

Predicted 3,070 4,880 6,240 9,570 11,100 15,200

Weighted 6,410 9,140 11,100 16,200 19,000 26,700

01546400 3 Observed 568 939 1,260 2,270 2,840 4,630

Predicted 681 1,210 1,660 2,880 3,500 5,250

Weighted 581 992 1,370 2,470 3,070 4,840

01546500 3 Observed 708 1,330 1,950 4,200 5,680 11,000

Predicted 885 1,570 2,160 3,770 4,590 6,910

Weighted 715 1,340 1,970 4,140 5,520 10,400

01547100 3 Observed 1,230 2,270 3,250 6,610 8,680 15,700

Predicted 1,400 2,440 3,330 5,710 6,900 10,300

Weighted 1,240 2,290 3,270 6,420 8,290 14,500

01547200 3 Observed 5,040 8,370 11,200 19,400 23,900 37,200

Predicted 3,370 5,550 7,310 11,800 14,000 19,900

Weighted 4,950 8,100 10,700 18,100 22,100 34,100

01547500 3 Observed 4,290 6,190 7,530 10,700 12,100 15,700

Predicted 3,810 6,090 7,890 12,400 14,500 20,200

Weighted 4,220 6,170 7,650 11,400 13,100 17,600

01547700 3 Observed 1,210 2,210 3,160 6,370 8,350 15,000

Predicted 1,640 2,660 3,440 5,360 6,270 8,680

Weighted 1,230 2,250 3,190 6,190 7,970 13,900

01547800 3 Observed 315 518 687 1,180 1,440 2,220

Predicted 478 783 1,010 1,590 1,860 2,570

Weighted 333 567 766 1,310 1,580 2,330

01547950 3 Observed 2,400 3,920 5,150 8,590 10,400 15,500

Predicted 4,070 6,280 7,910 11,800 13,600 18,200

Weighted 2,520 4,200 5,600 9,290 11,100 16,100

01548005 3 Observed 8,030 12,500 15,800 23,800 27,500 37,100

Predicted 7,470 11,600 14,700 22,300 25,800 35,200

Weighted 8,010 12,400 15,700 23,600 27,300 36,900

01548020 3 Observed 61 112 159 313 403 697

Predicted 107 185 247 407 484 692

Weighted 67 128 184 347 433 695
Appendix 2 41

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01548500 1 Observed 12,000 19,400 25,700 44,000 54,000 83,700

Predicted 17,400 27,700 35,700 56,800 67,300 95,800

Weighted 12,200 20,000 26,600 45,600 55,800 85,300

01549000 1 Observed 21,100 29,200 34,300 44,900 49,100 58,700

Predicted 21,000 33,200 42,700 67,800 80,300 114,000

Weighted 21,100 30,500 37,800 56,600 65,500 88,400

01549500 1 Observed 1,820 2,980 3,900 6,420 7,720 11,300

Predicted 1,590 2,690 3,560 5,860 7,010 10,100

Weighted 1,810 2,950 3,860 6,330 7,600 11,100

01549700 1 Observed 19,300 31,400 41,500 70,200 85,600 130,000

Predicted 25,500 40,100 51,600 81,600 96,600 137,000

Weighted 19,700 32,400 43,000 72,600 88,000 132,000

01549780 1 Observed 248 421 572 1,030 1,300 2,110

Predicted 364 640 861 1,450 1,740 2,550

Weighted 265 474 662 1,200 1,480 2,290

01550000 1 Observed 6,650 10,800 14,100 23,400 28,200 41,800

Predicted 5,930 9,680 12,600 20,400 24,300 34,800

Weighted 6,620 10,700 14,000 23,000 27,700 40,900

01550500 1 Observed 9,790 17,900 25,500 50,600 65,700 115,000

Predicted 8,510 13,800 17,900 28,800 34,200 49,000

Weighted 9,550 16,700 22,700 40,300 50,300 82,100

01551000 1 Observed 273 515 711 1,240 1,500 2,190

Predicted 180 322 437 741 895 1,320

Weighted 256 457 607 1,000 1,200 1,750

01552000 1 Observed 14,900 22,600 28,600 44,900 53,200 76,500

Predicted 12,800 20,400 26,400 42,400 50,300 71,900

Weighted 14,800 22,400 28,400 44,500 52,800 75,900

01552100 1 Observed 398 707 992 1,920 2,480 4,280

Predicted 479 832 1,120 1,900 2,300 3,410

Weighted 410 739 1,030 1,910 2,400 3,910

01552500 1 Observed 1,610 2,340 2,860 4,150 4,760 6,320

Predicted 1,070 1,820 2,420 4,010 4,800 6,970

Weighted 1,590 2,290 2,810 4,130 4,770 6,440

01553005 1 Observed 7,730 13,500 18,800 35,900 46,000 78,600

Predicted 6,530 10,600 13,900 22,400 26,700 38,200

Weighted 7,540 12,800 17,200 30,200 37,500 60,400

01553050 1 Observed 597 1,160 1,640 3,070 3,840 6,070

Predicted 881 1,510 2,020 3,350 4,010 5,840

Weighted 622 1,210 1,720 3,150 3,890 6,000
42 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01553130 1 Observed 149 361 587 1,440 2,000 3,990

Predicted 276 489 660 1,110 1,340 1,960

Weighted 173 400 615 1,290 1,680 2,980

01553600 1 Observed 789 1,520 2,220 4,550 5,970 10,700

Predicted 470 819 1,100 1,850 2,220 3,250

Weighted 743 1,350 1,870 3,480 4,420 7,520

01553700 1 Observed 2,320 3,110 3,630 4,820 5,340 6,590

Predicted 1,990 3,340 4,410 7,270 8,700 12,600

Weighted 2,290 3,150 3,830 5,620 6,480 8,690

01555000 3 Observed 5,390 9,080 12,200 21,600 26,800 42,200

Predicted 4,700 7,380 9,410 14,400 16,700 22,900

Weighted 5,360 8,970 12,000 20,700 25,500 39,800

01555500 3 Observed 4,420 7,880 11,300 23,100 30,700 57,100

Predicted 5,550 8,880 11,400 17,600 20,500 28,300

Weighted 4,460 7,940 11,300 22,400 29,400 53,500

01555800 3 Observed 101 164 217 368 450 688

Predicted 99 176 239 402 483 705

Weighted 101 167 223 380 462 694

01556000 3 Observed 6,350 9,820 12,500 19,200 22,400 31,100

Predicted 4,880 7,690 9,820 15,000 17,500 24,000

Weighted 6,310 9,710 12,300 18,700 21,900 30,300

01556400 3 Observed 204 371 525 1,020 1,310 2,230

Predicted 243 417 556 912 1,090 1,550

Weighted 209 381 533 981 1,230 1,990

01556500 3 Observed 2,570 3,990 5,030 7,580 8,780 11,800

Predicted 2,400 3,770 4,790 7,250 8,390 11,400

Weighted 2,560 3,960 4,990 7,510 8,690 11,700

01557100 3 Observed 95 170 228 378 450 638

Predicted 108 189 254 423 506 732

Weighted 96 173 234 392 468 668

01557500 3 Observed 1,410 2,250 2,890 4,510 5,280 7,320

Predicted 1,350 2,180 2,820 4,370 5,110 7,040

Weighted 1,410 2,250 2,880 4,490 5,260 7,280

01558000 3 Observed 5,130 8,440 11,300 20,200 25,200 40,800

Predicted 3,890 6,170 7,910 12,200 14,200 19,500

Weighted 5,080 8,270 11,000 19,100 23,600 37,800

01559000 3 Observed 13,500 21,700 28,600 48,800 59,700 92,200

Predicted 9,870 15,500 19,800 30,300 35,200 48,400

Weighted 13,400 21,400 28,100 47,100 57,400 88,000
Appendix 2 43

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01559500 3 Observed 2,520 3,700 4,610 7,010 8,210 11,500

Predicted 3,550 5,630 7,200 11,000 12,800 17,500

Weighted 2,610 3,990 5,130 8,080 9,480 13,100

01559700 3 Observed 293 547 773 1,470 1,860 3,040

Predicted 248 421 555 897 1,060 1,500

Weighted 287 517 707 1,250 1,540 2,440

01559790 3 Observed 2,840 5,070 6,870 11,700 14,200 20,900

Predicted 3,340 5,140 6,450 9,570 11,000 14,700

Weighted 2,930 5,090 6,720 10,800 12,700 18,000

01560000 3 Observed 4,310 6,910 9,060 15,200 18,500 28,200

Predicted 4,190 6,510 8,220 12,300 14,200 19,200

Weighted 4,310 6,880 8,980 14,800 17,900 26,900

01561000 3 Observed 900 1,760 2,610 5,620 7,540 14,200

Predicted 1,290 2,070 2,670 4,120 4,800 6,590

Weighted 935 1,810 2,620 5,220 6,780 12,100

01562000 3 Observed 14,000 22,000 28,100 43,300 50,600 69,800

Predicted 12,100 18,400 23,000 34,200 39,300 52,600

Weighted 14,000 21,900 27,700 42,400 49,400 68,000

01562500 3 Observed 1,650 2,710 3,610 6,290 7,770 12,200

Predicted 2,600 4,100 5,210 7,890 9,140 12,400

Weighted 1,740 2,920 3,940 6,730 8,160 12,300

01563000 3 Observed 14,400 19,900 23,400 30,200 32,800 38,600

Predicted 14,300 21,300 26,300 38,000 43,300 57,000

Weighted 14,400 20,200 24,000 32,400 36,000 44,000

01563800 3 Observed 166 266 344 552 656 942

Predicted 142 229 293 448 520 707

Weighted 163 258 330 515 606 856

01564500 3 Observed 6,030 10,500 14,400 26,000 32,400 51,700

Predicted 5,430 8,540 10,900 16,500 19,200 26,100

Weighted 6,010 10,400 14,100 24,700 30,600 48,100

01564512 3 Observed 7,690 15,600 23,500 51,700 69,800 133,000

Predicted 7,020 11,000 13,900 21,100 24,400 33,200

Weighted 7,590 14,500 20,500 39,500 51,300 92,300

01565000 3 Observed 2,580 4,630 6,500 12,500 16,000 27,100

Predicted 3,200 5,230 6,830 10,800 12,800 18,000

Weighted 2,610 4,690 6,540 12,200 15,400 25,500

01565700 3 Observed 236 437 634 1,330 1,780 3,350

Predicted 197 370 524 953 1,180 1,830

Weighted 232 424 606 1,210 1,580 2,850
44 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01565920 3 Observed 302 628 957 2,150 2,920 5,620

Predicted 384 669 899 1,500 1,790 2,600

Weighted 312 636 941 1,920 2,520 4,550

01566000 3 Observed 6,120 9,650 12,300 19,000 22,200 30,600

Predicted 6,320 9,860 12,500 18,800 21,700 29,400

Weighted 6,130 9,660 12,300 19,000 22,200 30,500

01566500 3 Observed 2,400 3,690 4,610 6,740 7,700 10,000

Predicted 2,160 3,590 4,710 7,530 8,900 12,600

Weighted 2,380 3,680 4,630 6,950 8,030 10,700

01567500 3 Observed 747 1,500 2,270 5,160 7,090 14,100

Predicted 753 1,270 1,680 2,710 3,210 4,560

Weighted 747 1,480 2,200 4,750 6,410 12,500

01568000 3 Observed 6,700 11,000 14,600 24,500 29,800 44,600

Predicted 6,170 9,650 12,200 18,500 21,400 29,000

Weighted 6,680 11,000 14,400 23,800 28,700 42,700

01568500 3 Observed 314 669 1,030 2,380 3,260 6,400

Predicted 776 1,230 1,560 2,360 2,740 3,710

Weighted 335 714 1,090 2,380 3,180 5,980

01569340 3 Observed 306 592 892 2,060 2,860 5,950

Predicted 368 652 884 1,490 1,800 2,630

Weighted 311 600 890 1,920 2,590 5,100

01569800 3 Observed 232 408 579 1,190 1,570 2,940

Predicted 355 702 1,030 1,990 2,510 4,100

Weighted 243 451 667 1,400 1,830 3,250

01570000 3 Observed 6,890 10,200 12,700 19,600 23,100 32,900

Predicted 7,390 12,200 16,100 26,100 30,900 44,300

Weighted 6,900 10,300 13,000 20,400 24,200 34,400

01571000 3 Observed 1,340 2,190 2,830 4,470 5,260 7,330

Predicted 513 968 1,370 2,500 3,090 4,800

Weighted 1,280 2,030 2,580 4,010 4,740 6,730

01571500 3 Observed 2,600 4,260 5,770 10,600 13,500 22,700

Predicted 3,800 6,290 8,290 13,400 15,800 22,600

Weighted 2,650 4,420 6,040 11,000 13,800 22,700

01571820 3 Observed 1,670 3,000 4,190 7,980 10,200 17,100

Predicted 1,670 2,710 3,500 5,450 6,370 8,820

Weighted 1,670 2,900 3,900 6,680 8,170 12,800

01572000 3 Observed 1,240 2,030 2,700 4,700 5,820 9,210

Predicted 1,600 2,680 3,530 5,670 6,700 9,500

Weighted 1,290 2,170 2,940 5,060 6,160 9,320
Appendix 2 45

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01572025 3 Observed 3,410 5,390 7,050 11,900 14,500 22,200

Predicted 4,070 6,520 8,390 13,000 15,100 20,800

Weighted 3,510 5,670 7,470 12,300 14,700 21,600

01572190 3 Observed 4,930 7,750 10,000 16,300 19,600 29,000

Predicted 5,290 8,400 10,700 16,400 19,100 26,200

Weighted 4,980 7,900 10,200 16,400 19,400 27,900

01572900 3 Observed 1,240 2,020 2,650 4,370 5,250 7,700

Predicted 603 1,090 1,490 2,580 3,120 4,670

Weighted 1,160 1,830 2,340 3,750 4,490 6,630

01573000 3 Observed 9,290 14,100 17,900 28,700 34,400 50,800

Predicted 10,200 16,000 20,400 31,100 36,200 49,500

Weighted 9,320 14,200 18,100 29,000 34,600 50,600

01573160 3 Observed 908 1,580 2,200 4,320 5,630 10,000

Predicted 1,230 2,290 3,250 5,940 7,360 11,500

Weighted 949 1,730 2,490 4,900 6,260 10,600

01573500 3 Observed 587 1,190 1,790 3,820 5,080 9,280

Predicted 762 1,310 1,760 2,890 3,450 4,970

Weighted 608 1,220 1,780 3,510 4,510 7,800

01573560 3 Observed 10,200 15,500 19,800 31,500 37,600 54,800

Predicted 11,600 18,700 24,100 37,500 43,900 61,100

Weighted 10,300 16,000 20,600 33,000 39,300 56,500

01574000 2 Observed 15,000 22,100 28,300 47,500 58,500 93,100

Predicted 12,400 19,700 25,700 41,700 49,700 71,600

Weighted 14,900 22,000 28,100 46,700 57,100 89,300

01574500 2 Observed 1,980 3,370 4,620 8,610 11,000 18,500

Predicted 3,140 5,230 6,930 11,500 13,900 20,400

Weighted 2,040 3,570 5,000 9,390 11,800 19,100

01574800 2 Observed 215 579 1,070 3,740 6,130 18,300

Predicted 509 967 1,360 2,490 3,100 4,860

Weighted 247 662 1,160 3,180 4,670 11,500

01575000 2 Observed 2,200 3,850 5,410 10,600 13,900 24,700

Predicted 4,500 7,600 10,200 17,200 20,700 30,800

Weighted 2,300 4,200 6,080 12,200 15,600 26,400

01576085 2 Observed 721 1,190 1,550 2,480 2,930 4,120

Predicted 454 796 1,070 1,830 2,220 3,320

Weighted 688 1,100 1,390 2,160 2,560 3,680

01576320 2 Observed 538 823 1,030 1,560 1,810 2,450

Predicted 438 779 1,060 1,830 2,230 3,350

Weighted 532 818 1,040 1,640 1,940 2,760
46 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01576500 2 Observed 7,410 12,200 16,000 26,700 32,300 48,200

Predicted 8,100 12,200 15,400 23,700 27,700 38,600

Weighted 7,430 12,200 16,000 26,300 31,600 46,500

01576754 2 Observed 10,900 15,300 18,400 25,900 29,300 37,900

Predicted 10,400 15,000 18,500 27,500 31,900 43,400

Weighted 10,800 15,200 18,400 26,500 30,400 40,400

01577500 2 Observed 5,280 8,830 12,100 22,600 28,800 49,200

Predicted 4,870 8,270 11,100 18,900 22,800 34,000

Weighted 5,230 8,710 11,800 20,800 25,800 41,300

01578200 2 Observed 440 861 1,270 2,680 3,570 6,560

Predicted 534 1,010 1,420 2,590 3,200 5,010

Weighted 444 875 1,290 2,660 3,470 6,120

01578400 2 Observed 611 1,270 2,000 5,040 7,270 16,200

Predicted 500 909 1,250 2,200 2,700 4,130

Weighted 601 1,200 1,800 3,880 5,260 10,600

01600700 4 Observed 438 817 1,170 2,350 3,060 5,390

Predicted 479 825 1,110 1,920 2,330 3,530

Weighted 444 819 1,150 2,190 2,790 4,730

01601000 4 Observed 4,770 7,200 9,060 13,900 16,200 22,600

Predicted 4,480 7,110 9,180 14,700 17,600 25,500

Weighted 4,750 7,190 9,080 14,100 16,600 23,300

01601500 4 Observed 5,930 9,660 13,000 23,300 29,400 48,500

Predicted 6,990 10,900 14,000 22,100 26,300 37,900

Weighted 5,990 9,790 13,100 23,100 28,900 46,800

01603500 4 Observed 920 1,580 2,120 3,640 4,430 6,670

Predicted 1,180 1,970 2,620 4,380 5,280 7,860

Weighted 938 1,630 2,210 3,790 4,600 6,890

01613050 4 Observed 373 730 1,080 2,260 3,000 5,480

Predicted 493 849 1,150 1,970 2,390 3,620

Weighted 383 748 1,090 2,190 2,860 5,070

01613500 4 Observed 4,560 8,460 12,200 25,200 33,400 61,400

Predicted 4,790 7,590 9,790 15,700 18,700 27,100

Weighted 4,620 8,120 11,100 20,100 25,500 43,800

01614090 4 Observed 100 199 297 634 845 1,560

Predicted 261 461 630 1,100 1,350 2,060

Weighted 124 265 403 810 1,030 1,740

01614500 4 Observed 7,440 11,000 13,900 22,100 26,400 38,800

Predicted 12,600 19,200 24,300 37,700 44,500 63,600

Weighted 7,720 11,800 15,300 24,700 29,400 42,600
Appendix 2 47

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

01638900 4 Observed 1,290 2,360 3,350 6,570 8,490 14,700

Predicted 563 964 1,300 2,220 2,700 4,070

Weighted 1,170 1,990 2,670 4,890 6,250 10,800

03007800 3 Observed 5,290 7,020 8,190 10,800 12,000 14,800

Predicted 5,520 8,300 10,300 14,900 17,100 22,400

Weighted 5,300 7,210 8,590 11,900 13,300 16,800

03008000 3 Observed 451 972 1,510 3,500 4,800 9,450

Predicted 341 566 740 1,170 1,380 1,930

Weighted 437 885 1,300 2,670 3,540 6,700

03009680 3 Observed 4,040 5,720 7,000 10,300 11,900 16,400

Predicted 3,820 5,800 7,220 10,600 12,100 16,000

Weighted 4,020 5,740 7,050 10,400 12,000 16,200

03010500 3 Observed 7,240 11,900 16,100 29,500 37,400 63,200

Predicted 9,840 14,200 17,300 24,200 27,300 35,000

Weighted 7,320 12,000 16,100 28,900 36,300 60,100

03010655 3 Observed 2,090 2,930 3,480 4,630 5,110 6,190

Predicted 2,600 4,000 5,020 7,450 8,570 11,400

Weighted 2,130 3,090 3,770 5,350 6,020 7,560

03011020 3 Observed 23,200 31,200 36,800 50,100 56,300 71,700

Predicted 24,800 35,200 42,300 58,200 65,300 82,900

Weighted 23,200 31,400 37,200 50,900 57,200 72,800

03011800 3 Observed 1,190 2,050 2,770 4,850 5,950 9,160

Predicted 1,160 1,810 2,300 3,450 3,990 5,360

Weighted 1,190 2,030 2,700 4,550 5,530 8,340

03013000 3 Observed 3,690 5,100 6,090 8,430 9,480 12,100

Predicted 5,410 7,790 9,420 13,100 14,700 18,800

Weighted 3,770 5,330 6,480 9,170 10,300 13,200

03015000 3 Observed 7,710 10,200 11,800 15,300 16,800 20,400

Predicted 11,700 16,100 19,000 25,400 28,100 34,900

Weighted 7,860 10,600 12,500 16,600 18,400 22,400

03015080 3 Observed 660 811 904 1,100 1,170 1,350

Predicted 401 661 860 1,360 1,590 2,210

Weighted 628 780 892 1,190 1,320 1,650

03015280 3 Observed 496 612 680 811 861 969

Predicted 460 736 940 1,440 1,670 2,270

Weighted 491 641 759 1,050 1,180 1,480

03015390 3 Observed 828 1,150 1,380 1,950 2,230 2,950

Predicted 456 720 912 1,380 1,590 2,140

Weighted 780 1,050 1,250 1,750 1,990 2,650
48 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

03015500 3 Observed 7,510 10,100 11,800 15,300 16,800 20,000

Predicted 6,340 9,280 11,300 15,900 18,000 23,200

Weighted 7,480 10,100 11,800 15,400 16,900 20,400

03017500 3 Observed 5,820 8,610 10,600 15,200 17,300 22,500

Predicted 5,620 8,550 10,700 15,700 18,000 23,800

Weighted 5,810 8,610 10,600 15,300 17,400 22,800

03019000 3 Observed 9,110 12,000 13,900 17,800 19,400 23,000

Predicted 9,830 14,600 18,000 25,900 29,500 38,600

Weighted 9,200 12,600 15,000 20,700 23,100 28,700

03020440 3 Observed 310 411 478 628 693 847

Predicted 221 375 495 801 949 1,340

Weighted 297 402 483 697 798 1,050

03020500 3 Observed 7,740 10,900 13,100 18,500 21,000 27,500

Predicted 6,800 10,200 12,600 18,300 20,900 27,400

Weighted 7,710 10,800 13,100 18,500 21,000 27,500

03021350 3 Observed 3,810 4,910 5,580 6,900 7,420 8,560

Predicted 2,340 3,560 4,420 6,460 7,390 9,760

Weighted 3,690 4,720 5,360 6,790 7,420 8,870

03021410 3 Observed 3,120 4,800 6,120 9,700 11,500 16,600

Predicted 1,310 1,980 2,440 3,510 4,000 5,230

Weighted 2,890 4,210 5,130 7,560 8,840 12,600

03021700 3 Observed 291 432 537 797 921 1,250

Predicted 202 348 464 763 908 1,300

Weighted 279 413 516 784 916 1,270

03022500 3 Observed 10,500 13,800 15,900 20,400 22,300 26,500

Predicted 10,700 15,100 18,200 25,000 28,000 35,400

Weighted 10,500 14,100 16,600 22,100 24,400 29,900

03022540 3 Observed 1,180 1,770 2,180 3,140 3,580 4,630

Predicted 1,030 1,630 2,070 3,140 3,640 4,930

Weighted 1,170 1,750 2,160 3,140 3,590 4,710

03023000 3 Observed 1,580 2,180 2,630 3,760 4,310 5,780

Predicted 2,010 2,960 3,610 5,080 5,740 7,400

Weighted 1,620 2,300 2,830 4,130 4,720 6,240

03023500 3 Observed 16,000 22,000 26,100 35,800 40,200 51,000

Predicted 15,100 21,100 25,100 33,900 37,700 47,200

Weighted 15,900 21,800 25,800 35,100 39,200 49,500

03024000 3 Observed 14,200 17,600 19,700 23,800 25,400 29,000

Predicted 15,600 21,800 25,900 35,000 39,000 48,800

Weighted 14,300 18,200 20,700 26,200 28,500 33,400
Appendix 2 49

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

03025000 3 Observed 5,290 7,320 8,580 11,200 12,200 14,500

Predicted 4,130 6,270 7,800 11,400 13,000 17,300

Weighted 5,230 7,210 8,480 11,200 12,400 15,000

03025200 3 Observed 235 435 619 1,210 1,560 2,680

Predicted 297 506 671 1,090 1,300 1,850

Weighted 243 451 634 1,170 1,460 2,360

03026400 3 Observed 463 576 641 763 808 903

Predicted 299 510 677 1,100 1,310 1,860

Weighted 442 562 651 884 992 1,250

03026500 3 Observed 399 736 1,050 2,030 2,610 4,440

Predicted 325 536 697 1,100 1,290 1,790

Weighted 395 718 1,000 1,880 2,380 3,990

03028000 3 Observed 2,170 3,280 4,070 5,980 6,860 9,050

Predicted 1,820 2,840 3,600 5,400 6,240 8,390

Weighted 2,160 3,240 4,010 5,880 6,740 8,930

03029000 3 Observed 9,790 16,000 20,900 34,400 41,300 60,500

Predicted 6,350 9,430 11,600 16,600 18,900 24,700

Weighted 9,130 14,000 17,400 26,100 30,500 43,400

03029200 3 Observed 273 499 709 1,400 1,810 3,170

Predicted 331 554 726 1,160 1,360 1,910

Weighted 280 510 713 1,320 1,660 2,740

03029400 3 Observed 341 506 618 866 972 1,220

Predicted 537 889 1,160 1,830 2,150 3,010

Weighted 366 588 769 1,210 1,410 1,870

03029500 3 Observed 17,200 24,900 30,400 44,100 50,600 67,200

Predicted 15,100 22,100 27,000 38,300 43,400 56,200

Weighted 17,200 24,700 30,100 43,300 49,500 65,600

03030500 3 Observed 21,800 31,600 38,700 56,600 65,000 87,100

Predicted 17,800 26,000 31,700 44,900 50,900 65,900

Weighted 21,600 31,100 37,900 54,800 62,800 83,700

03031000 3 Observed 26,500 35,800 41,700 54,000 59,000 70,400

Predicted 22,500 32,800 40,000 56,600 64,000 82,800

Weighted 25,800 34,900 41,000 55,200 61,400 76,300

03031780 3 Observed 108 180 231 350 401 525

Predicted 114 196 261 428 509 727

Weighted 109 184 240 380 444 604

03031950 3 Observed 492 739 906 1,270 1,420 1,780

Predicted 356 601 791 1,270 1,510 2,130

Weighted 474 708 873 1,270 1,460 1,910
50 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

03032500 3 Observed 11,900 17,900 22,800 36,200 43,100 62,900

Predicted 11,100 16,500 20,400 29,400 33,500 43,800

Weighted 11,800 17,900 22,600 35,500 42,100 60,900

03034000 3 Observed 4,440 7,100 9,360 16,000 19,700 30,800

Predicted 4,260 6,580 8,280 12,300 14,200 19,100

Weighted 4,430 7,070 9,260 15,500 19,000 29,200

03034500 3 Observed 3,100 4,480 5,500 8,080 9,330 12,600

Predicted 2,670 4,210 5,360 8,120 9,420 12,800

Weighted 3,090 4,460 5,480 8,090 9,340 12,700

03035000 3 Observed 7,420 10,100 12,200 17,200 19,700 26,200

Predicted 7,300 11,000 13,600 19,700 22,500 29,700

Weighted 7,410 10,300 12,500 18,000 20,600 27,300

03038000 3 Observed 4,960 7,520 9,650 15,800 19,200 29,100

Predicted 5,260 8,130 10,200 15,300 17,600 23,600

Weighted 4,970 7,560 9,700 15,700 18,900 28,300

03039000 3 Observed 9,300 12,900 15,200 19,800 21,700 25,700

Predicted 6,790 10,300 12,800 18,800 21,500 28,600

Weighted 9,090 12,500 14,700 19,600 21,600 26,500

03039200 4 Observed 134 206 261 401 470 651

Predicted 200 356 489 864 1,060 1,630

Weighted 145 248 342 592 714 1,030

03040000 4 Observed 10,400 16,800 22,100 36,800 44,500 66,500

Predicted 11,700 17,900 22,600 35,300 41,700 59,500

Weighted 10,400 16,900 22,100 36,600 44,100 65,700

03041000 4 Observed 5,340 9,050 12,300 22,400 28,200 46,000

Predicted 5,500 8,670 11,200 17,800 21,100 30,600

Weighted 5,350 9,010 12,200 21,700 27,100 43,800

03041500 4 Observed 16,500 26,900 35,900 62,800 77,800 124,000

Predicted 17,400 26,300 33,000 50,800 59,800 84,900

Weighted 16,600 26,900 35,500 60,900 75,100 118,000

03042000 4 Observed 6,460 10,400 13,700 23,600 29,000 45,400

Predicted 5,650 8,890 11,400 18,200 21,700 31,400

Weighted 6,410 10,200 13,400 22,600 27,600 42,900

03042170 4 Observed 317 408 465 585 634 745

Predicted 238 420 576 1,010 1,240 1,890

Weighted 299 412 513 795 932 1,290

03042200 4 Observed 434 799 1,150 2,360 3,120 5,710

Predicted 359 626 850 1,470 1,800 2,730

Weighted 422 752 1,050 2,010 2,600 4,580
Appendix 2 51

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

03042500 4 Observed 5,210 7,390 8,980 12,900 14,800 19,700

Predicted 5,120 8,090 10,400 16,700 19,800 28,800

Weighted 5,200 7,600 9,510 14,500 17,000 23,400

03043000 4 Observed 11,200 17,300 22,300 36,800 44,700 67,900

Predicted 10,300 15,800 20,100 31,400 37,200 53,200

Weighted 11,200 17,100 21,900 35,700 43,100 65,000

03045000 4 Observed 6,030 9,300 12,000 19,500 23,400 34,800

Predicted 5,140 8,110 10,500 16,700 19,900 28,800

Weighted 5,980 9,190 11,800 19,000 22,800 33,900

03045500 4 Observed 7,070 11,800 16,000 28,300 35,100 55,900

Predicted 7,420 11,600 14,800 23,300 27,700 39,900

Weighted 7,130 11,800 15,600 26,300 32,200 49,800

03047500 4 Observed 39,700 59,900 76,200 122,000 146,000 215,000

Predicted 36,100 53,000 65,700 98,800 116,000 162,000

Weighted 39,500 59,000 74,400 117,000 139,000 204,000

03049000 4 Observed 3,890 5,950 7,610 12,200 14,600 21,500

Predicted 4,250 6,760 8,740 14,000 16,700 24,400

Weighted 3,910 6,030 7,760 12,500 15,000 22,000

03049800 4 Observed 270 666 1,140 3,270 4,930 11,900

Predicted 293 514 701 1,220 1,500 2,280

Weighted 272 644 1,060 2,800 4,140 9,840

03062500 4 Observed 1,590 2,720 3,680 6,490 8,020 12,600

Predicted 2,210 3,600 4,720 7,730 9,280 13,700

Weighted 1,630 2,830 3,850 6,740 8,270 12,800

03070420 4 Observed 61 90 111 162 186 247

Predicted 62 115 162 297 369 577

Weighted 61 99 134 231 280 410

03070500 4 Observed 7,130 10,300 12,900 20,000 23,700 34,300

Predicted 5,850 9,190 11,800 18,800 22,400 32,300

Weighted 7,090 10,200 12,800 19,900 23,600 34,100

03072000 4 Observed 7,200 10,500 12,700 17,700 19,800 24,800

Predicted 6,560 10,300 13,200 20,900 24,800 35,800

Weighted 7,160 10,500 12,800 18,200 20,600 26,400

03072590 4 Observed 662 978 1,210 1,770 2,030 2,700

Predicted 703 1,200 1,600 2,720 3,300 4,960

Weighted 670 1,050 1,360 2,200 2,610 3,690

03072840 4 Observed 4,410 8,250 11,800 23,200 29,900 51,300

Predicted 4,140 6,600 8,540 13,700 16,400 23,800

Weighted 4,340 7,600 10,300 18,100 22,700 37,100
52 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

03072880 4 Observed 842 1,550 2,150 3,790 4,630 6,960

Predicted 752 1,280 1,710 2,890 3,510 5,260

Weighted 833 1,510 2,050 3,540 4,320 6,520

03073000 4 Observed 6,150 8,620 10,200 13,300 14,500 17,300

Predicted 5,350 8,440 10,900 17,300 20,600 29,900

Weighted 6,100 8,600 10,200 14,000 15,500 19,200

03074300 4 Observed 151 259 350 613 754 1,170

Predicted 206 366 502 886 1,090 1,670

Weighted 160 287 400 718 883 1,350

03074500 4 Observed 2,260 3,240 3,920 5,510 6,220 7,990

Predicted 2,520 4,080 5,330 8,710 10,400 15,300

Weighted 2,280 3,320 4,110 6,040 6,930 9,140

03078000 4 Observed 2,010 2,920 3,650 5,680 6,740 9,800

Predicted 2,190 3,570 4,680 7,670 9,200 13,500

Weighted 2,020 3,010 3,840 6,130 7,300 10,600

03078500 4 Observed 1,030 1,880 2,650 5,070 6,480 10,900

Predicted 991 1,660 2,210 3,720 4,500 6,710

Weighted 1,030 1,840 2,560 4,740 5,990 9,930

03079000 4 Observed 10,800 16,100 20,200 31,600 37,400 53,800

Predicted 10,100 15,600 19,800 30,900 36,600 52,500

Weighted 10,800 16,000 20,200 31,500 37,300 53,600

03080000 4 Observed 4,050 5,850 7,090 9,920 11,200 14,200

Predicted 3,830 6,110 7,920 12,800 15,200 22,200

Weighted 4,040 5,870 7,170 10,300 11,700 15,100

03082200 4 Observed 650 935 1,150 1,730 2,010 2,790

Predicted 437 755 1,020 1,760 2,150 3,250

Weighted 614 884 1,110 1,740 2,070 2,970

03082500 4 Observed 32,600 46,000 55,900 80,800 92,800 125,000

Predicted 28,900 42,800 53,300 80,800 94,600 133,000

Weighted 32,400 45,600 55,500 80,800 93,200 126,000

03083000 4 Observed 235 423 592 1,120 1,430 2,390

Predicted 174 311 428 759 933 1,430

Weighted 231 409 566 1,050 1,330 2,220

03083500 4 Observed 36,700 56,300 71,200 110,000 128,000 178,000

Predicted 35,900 52,700 65,400 98,300 115,000 161,000

Weighted 36,600 55,400 69,400 105,000 123,000 172,000

03083600 4 Observed 184 342 492 997 1,310 2,340

Predicted 217 385 528 930 1,140 1,750

Weighted 189 353 504 972 1,250 2,130
Appendix 2 53

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

03084000 4 Observed 422 696 896 1,370 1,590 2,120

Predicted 232 411 563 990 1,210 1,860

Weighted 408 657 836 1,290 1,510 2,070

03084500 4 Observed 2,210 3,390 4,250 6,300 7,240 9,580

Predicted 1,990 3,260 4,280 7,040 8,450 12,500

Weighted 2,190 3,370 4,250 6,480 7,540 10,300

03085500 3 Observed 5,460 8,120 9,940 14,000 15,800 19,900

Predicted 7,220 11,200 14,200 21,200 24,500 33,100

Weighted 5,520 8,310 10,300 14,800 16,800 21,500

03086100 3 Observed 622 1,010 1,320 2,180 2,630 3,870

Predicted 762 1,290 1,700 2,750 3,250 4,620

Weighted 643 1,080 1,440 2,410 2,880 4,170

03098700 3 Observed 671 857 982 1,270 1,390 1,700

Predicted 484 760 959 1,440 1,660 2,220

Weighted 651 840 977 1,320 1,470 1,860

03100000 3 Observed 3,130 4,840 6,170 9,710 11,500 16,400

Predicted 2,050 2,720 3,120 3,970 4,320 5,170

Weighted 2,910 4,160 4,950 6,890 7,900 10,800

03101000 3 Observed 540 1,020 1,430 2,610 3,240 5,030

Predicted 450 768 1,020 1,660 1,970 2,800

Weighted 529 969 1,320 2,290 2,800 4,270

03102500 3 Observed 2,480 3,630 4,420 6,240 7,050 9,020

Predicted 2,460 3,660 4,490 6,410 7,280 9,470

Weighted 2,480 3,630 4,430 6,260 7,080 9,070

03102950 3 Observed 1,420 1,960 2,310 3,010 3,290 3,900

Predicted 1,880 2,680 3,200 4,350 4,860 6,110

Weighted 1,450 2,050 2,460 3,310 3,660 4,420

03103000 3 Observed 2,910 4,200 5,010 6,650 7,290 8,680

Predicted 2,990 4,210 4,990 6,720 7,480 9,340

Weighted 2,920 4,200 5,010 6,660 7,320 8,800

03104000 3 Observed 7,940 12,100 15,200 22,600 26,100 35,000

Predicted 8,570 11,700 13,600 17,800 19,600 24,100

Weighted 8,010 12,000 14,800 21,000 23,900 31,200

03104500 3 Observed 8,750 13,100 16,500 25,300 29,700 41,600

Predicted 11,400 15,600 18,300 24,100 26,600 32,800

Weighted 9,080 13,600 17,000 24,900 28,600 38,400

03104760 3 Observed 186 327 443 767 934 1,400

Predicted 113 189 246 390 459 640

Weighted 172 285 368 590 706 1,040
54 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals

Appendix 2. Flood-flow magnitudes for selected recurrence intervals computed from observed streamflow-gaging station data, 

predicted from regional regression equations, and a weighted average for streamflow-gaging stations used in analysis.—Continued

U.S. Geological 

Survey 

streamflowgaging station 

number

Flood-flow 

region Type

Flood-flow estimates, in cubic feet per second

2-year 5-year 10-year 50-year 100-year 500-year

03106000 3 Observed 7,920 11,000 13,300 19,100 21,900 29,300

Predicted 9,340 14,400 18,100 26,800 30,900 41,500

Weighted 7,960 11,200 13,700 19,900 22,900 30,600

03106500 3 Observed 7,480 10,900 13,200 18,500 20,800 26,300

Predicted 7,820 11,400 13,800 19,400 21,900 28,200

Weighted 7,500 10,900 13,300 18,700 21,000 26,600

03108000 3 Observed 3,610 5,600 7,150 11,300 13,400 19,200

Predicted 5,370 8,430 10,700 16,200 18,800 25,500

Weighted 3,660 5,750 7,420 11,800 14,000 19,900

03109000 3 Observed 382 614 797 1,290 1,540 2,230

Predicted 335 573 761 1,240 1,480 2,110

Weighted 378 609 791 1,280 1,520 2,200

03109500 3 Observed 8,980 13,300 16,400 24,000 27,600 36,800

Predicted 12,400 19,000 23,800 35,200 40,500 54,100

Weighted 9,090 13,600 17,000 25,200 29,100 38,800

03111150 3 Observed 533 933 1,240 2,010 2,380 3,310

Predicted 521 885 1,170 1,900 2,250 3,210

Weighted 532 923 1,220 1,970 2,330 3,270

04213000 3 Observed 6,130 8,950 10,800 14,900 16,600 20,500

Predicted 4,810 7,380 9,250 13,700 15,700 21,000

Weighted 6,080 8,840 10,600 14,700 16,500 20,600

04213040 3 Observed 131 220 286 448 524 714

Predicted 140 235 308 491 578 811

Weighted 132 222 290 458 537 738

04213075 3 Observed 321 495 619 912 1,050 1,370

Predicted 293 516 697 1,170 1,410 2,050

Weighted 317 499 641 1,000 1,180 1,620

04213200 3 Observed 732 1,170 1,510 2,470 2,960 4,350

Predicted 502 862 1,150 1,890 2,250 3,220

Weighted 717 1,130 1,460 2,350 2,810 4,120
Appendix 3 55

Appendix 3. Flood-flow magnitudes for selected recurrence intervals for streamflow-gaging stations in Pennsylvania with drainage areas less than 2,000 square miles and streamflow substantially affected by upstream regulation.—Continued[Data from these streamflow-gaging stations were not included in the regression analysis; mi2, square miles; water year, 12-month period October 1- September 30; all flood flows in cubic feet per second]

U.S. Geological 

Survey 

streamflow-gaging 

station

Station name

Drainage 

area 

(mi2)

Period of 

record 

(water year)1

Flood flows, computed from streamflow-gaging-station data

2-year 5-year 10-year 50-year 100-year

01429000 West Branch Lackawaxen River at Prompton, Pa. 59.7 1961-2006 1,350 2,070 2,580 3,830 4,40001429500 Dyberry Creek near Honesdale, Pa. 64.6 1960-2006 1,530 1,940 2,210 2,820 3,09001430000 Lackawaxen River near Honesdale, Pa. 164 1960-2006 3,890 5,720 7,120 10,700 12,50001431500 Lackawaxen River at Hawley, Pa. 290 1960-2006 6,630 10,300 13,300 21,900 26,50001447800 Lehigh River bl Francis E Walter Res nr White Haven, Pa. 290 1961-2006 5,680 7,900 9,470 13,200 14,90001449500 Wild Creek at Hatchery, Pa. 16.8 1959-78 191 308 400 643 76401449800 Pohopoco Cr bl Beltzville Dam nr Parryville, Pa. 96.4 1971-2006 1,300 1,570 1,720 2,010 2,11001451000 Lehigh River at Walnutport, Pa. 889 1961-2006 17,900 27,300 34,200 51,100 58,90001453000 Lehigh River at Bethlehem, Pa. 1,280 1961-2006 23,900 36,500 45,700 67,800 78,10001454700 Lehigh River at Glendon, Pa. 1,360 1967-2006 25,800 38,900 48,100 69,900 79,80001459500 Tohickon Creek near Pipersville, Pa. 97.4 1974-2006 6,200 10,200 13,400 21,900 26,10001464645 NB Neshaminy Cr bl Lake Galena nr New Britain, Pa. 16.2 1986-2006 627 1,410 2,160 4,620 6,07001464720 NB Neshaminy Creek at Chalfont, Pa. 31.5 1991-2006 1,800 3,960 6,110 13,500 18,10001470960 Tulpehocken Cr at Blue Marsh Damsite near Reading, Pa. 175 1979-2006 2,430 3,410 4,080 5,600 6,27001471000 Tulpehocken Creek near Reading, Pa. 211 1979-2006 2,650 3,740 4,510 6,290 7,10001471510 Schuylkill River at Reading, Pa. 880 1980-2006 16,600 26,800 34,600 54,900 64,80001472000 Schuylkill River at Pottstown, Pa. 1,150 1979-2006 21,100 30,300 36,900 53,100 60,60001480400 Birch Run near Wagontown, Pa. 4.55 1997-2006 162 309 441 845 1,07001480685 Marsh Creek near Downingtown, Pa. 20.3 1974-2006 331 488 594 826 92401480700 East Branch Brandywine Creek near Downingtown, Pa. 60.6 1974-2006 2,250 3,640 4,660 7,170 8,33001480870 East Branch Brandywine Creek below Downingtown, Pa. 89.9 1974-2006 3,320 5,100 6,410 9,640 11,20001518000 Tioga River at Tioga, Pa. 282 1980-2006 5,700 6,390 6,780 7,510 7,78001518700 Tioga River at Tioga Junction, Pa. 446 1980-2006 6,710 8,050 8,950 11,000 11,80001520000 Cowanesque River near Lawrenceville, Pa. 298 1980-2006 4,460 5,410 5,980 7,150 7,62001534300 Lackawanna River near Forest City, Pa. 38.8 1960-2006 759 961 1,080 1,300 1,39001534500 Lackawanna River at Archbald, Pa. 108 1960-2006 2,390 3,880 5,110 8,620 10,50001536000 Lackawanna River at Old Forge, Pa. 332 1960-2006 6,150 10,500 14,000 23,800 28,900
56 Regression Equations for Estimating Flood Flows for Selected Recurrence Intervals Appendix 3. Flood-flow magnitudes for selected recurrence intervals for streamflow-gaging stations in Pennsylvania with drainage areas less than 2,000 square miles and streamflow substantially affected by upstream regulation.—Continued [Data from these streamflow-gaging stations were not included in the regression analysis; mi2, square miles; water year, 12-month period October 1- September 30; all flood flows in cubic feet per second] U.S. Geological Survey streamflow-gaging station Station name Drainage area (mi2

)

Period of 

record 

(water year)1

Flood flows, computed from streamflow-gaging-station data

2-year 5-year 10-year 50-year 100-year

01541200 WB Susquehanna River near Curwensville, Pa. 367 1966-2006 4,780 5,650 6,210 7,430 7,95001541303 West Branch Susquehanna River at Hyde, Pa. 474 1979-2006 5,680 6,710 7,390 8,890 9,54001541500 Clearfield Creek at Dimeling, Pa. 371 1961-2006 6,240 9,030 11,100 16,600 19,30001542500 WB Susquehanna River at Karthaus, Pa. 1,460 1961-2006 20,000 30,300 38,800 63,100 76,00001544000 First Fork Sinnemahoning Cr near Sinnemahoning, Pa. 245 1956-2006 4,900 6,150 6,930 8,540 9,19001545000 Kettle Creek near Westport, Pa. 233 1962-2006 4,660 5,640 6,240 7,440 7,91001547500 Bald Eagle Creek at Blanchard, Pa. 339 1971-2006 2,860 3,590 4,020 4,900 5,24001563200 Rays Br Juniata River bl Rays Dam nr Huntingdon, Pa. 960 1973-2006 11,900 14,900 16,600 19,600 20,80001575500 Codorus Creek near York, Pa. 222 1947-2006 3,950 6,430 8,690 16,000 20,30001574500 Codorus Creek at Spring Grove, Pa. 75.5 1967-2006 1,600 3,060 4,580 10,300 14,30001575000 South Branch Codorus Creek near York, Pa. 117 1972-95 4,240 8,070 11,900 25,300 34,00003020000 Tionesta Creek at Tionesta Creek Dam, Pa. 479 1941-91 6,600 8,350 9,440 11,700 12,60003021520 French Creek near Union City, Pa. 221 1972-91 2,370 3,100 3,550 4,450 4,81003023100 French Creek at Meadville, Pa. 788 1989-2006 10,100 12,600 14,100 17,200 18,40003024000 French Creek at Utica, Pa. 1,030 1971-2006 12,100 14,700 16,200 19,000 20,00003022554 Woodcock Creek at Woodcock Creek Dam, Pa. 45.6 1975-91 608 775 877 1,090 1,17003027500 EB Clarion River at EB Clarion River Dam, Pa. 73.2 1953-91 581 904 1,170 1,910 2,31003028500 Clarion River at Johnsonburg, Pa. 204 1953-2006 3,880 5,690 7,050 10,500 12,20003036000 Mahoning Creek at Mahoning Creek Dam, Pa. 344 1941-91 4,910 6,560 7,730 10,500 11,80003039000 Crooked Creek at Crooked Creek Dam, Pa. 278 1941-91 3,780 4,840 5,470 6,730 7,22003042280 Yellow Creek near Homer City, Pa. 57.4 1971-2006 1,360 2,640 3,890 8,260 11,00003042500 Two Lick Creek at Graceton, Pa. 171 1969-2006 4,030 7,790 11,400 24,100 32,10003044000 Conemaugh River at Tunnelton, Pa. 1,360 1952-91 17,700 23,100 26,400 33,500 36,40003047000 Loyalhanna Creek at Loyalhanna Dam, Pa. 292 1942-91 3,800 4,810 5,440 6,730 7,25003048500 Kiskiminetas River at Vandergrift, Pa. 1,830 1942-2006 21,700 30,500 36,800 52,000 59,10003077500 Youghiogheny River at Youghiogheny River Dam, Pa. 436 1944-91 4,990 6,750 7,860 10,200 11,10003081000 Youghiogheny River below Confluence, Pa. 1,030 1942-2006 16,100 23,000 28,200 41,400 47,800
Appendix 3 57

Appendix 3. Flood-flow magnitudes for selected recurrence intervals for streamflow-gaging stations in Pennsylvania with drainage areas less than 2,000 square miles and streamflow substantially affected by upstream regulation.—Continued[Data from these streamflow-gaging stations were not included in the regression analysis; mi2, square miles; water year, 12-month period October 1- September 30; all flood flows in cubic feet per second]

U.S. Geological 

Survey 

streamflow-gaging 

station

Station name

Drainage 

area 

(mi2)

Period of 

record 

(water year)1

Flood flows, computed from streamflow-gaging-station data

2-year 5-year 10-year 50-year 100-year

03082500 Youghiogheny River at Connellsville, Pa. 1,330 1942-2006 23,800 35,700 44,800 68,200 79,70003083500 Youghiogheny River at Sutersville, Pa. 1,720 1942-2006 29,200 44,000 55,300 84,500 98,80003101500 Shenango River at Pymatuning Dam, Pa. 167 1935-2006 900 1,150 1,310 1,620 1,74003102850 Shenango River near Transfer, Pa. 337 1966-2006 4,480 5,190 5,560 6,170 6,38003103500 Shenango River at Sharpsville, Pa. 584 1939-91 4,840 7,660 9,920 16,100 19,30003106300 Muddy Creek near Portersville, Pa. 51.2 1970-2006 349 481 574 793 89203106500 Slippery Rock Creek at Wurtemburg, Pa. 398 1969-2006 6,240 8,020 9,060 11,100 11,900

2Water year is defined as a 12-month period beginning October 1 and ending September 30. The water year is designated by the calendar year in which it ends.

Roland and Stuckey— Regression Equations for Estimating Flood Flows for Ungaged Streams in Pennsylvania—Scientific Investigations Report 2008-5102

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