Selected Streamflow Statistics for 

Streamgaging Stations in 

Northeastern Maryland, 2006

By Kernell G. Ries III

Prepared in cooperation with the

University of Maryland, Baltimore County, 

Center for Urban Environmental Research and Education;

Baltimore City Department of Public Works; and

Baltimore County Department of Environmental Protection and 

Resource Management

Open-File Report 2006–1335

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: 2006

For product and ordering information:

World Wide Web: http://www.usgs.gov/pubprod

Telephone: 1-888-ASK-USGS

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

natural hazards, and the environment:

World Wide Web: http://www.usgs.gov

Telephone: 1-888-ASK-USGS

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

U.S. Government.

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Ries III, K.G., 2006, Selected streamflow statistics for streamgaging stations in northeastern Maryland, 2006: 

U.S. Geological Survey Open-File Report 2006–1335, 16 p.
iii

Contents

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

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

Physical Setting..............................................................................................................................................2

Computation of Statistics .............................................................................................................................2

Comparison With Previously Published Statistics .................................................................................14

Summary........................................................................................................................................................14

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

Figures

1. Map showing locations of streamgaging stations in northeastern Maryland...................3

Tables

1. Summary of streamgaging stations in northeastern Maryland for which streamflow 

statistics were computed............................................................................................................4

2. Descriptive statistics of the mean daily discharges for the period of record for 

streamgaging stations in northeastern Maryland...................................................................7

3. Flow-duration statistics for streamgaging stations in northeastern Maryland .................9

4. Low-flow frequency statistics for streamgaging stations in northeastern Maryland ....11

5. Comparison of low-flow frequency statistics computed from data available 

through climatic years 1989 and 2004 for streamgaging stations in northeastern 

Maryland with greater than 25 years of record.....................................................................15

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

Area

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Flow rate

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

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

 °C=(°F-32)/1.8

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

(NAVD 88).

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

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

Conversion Factors and Datums

Abstract

Streamflow statistics were calculated for 47 U.S. Geological Survey (USGS) streamgaging stations in northeastern 

Maryland, in cooperation with (1) the University of Maryland, 

Baltimore County, Center for Urban Environmental Research 

and Education; (2) the Baltimore City Department of Public 

Works; and (3) the Baltimore County Department of Environmental Protection and Resource Management. The statistics 

include the mean, minimum, maximum, and standard deviation of the daily mean discharges for the periods of record at 

the stations, as well as flow-duration and low-flow frequency 

statistics. The flow-duration statistics include the 1-, 2-, 5-, 

10-, 15-, 20-, 25-, 30-, 40-, 50-, 60-, 70-, 75-, 80-, 85-, 90-, 

95-, 98-, and 99-percent duration discharges. The low-flow 

frequency statistics include the average discharges for 1, 7, 

14, and 30 days that recur, on average, once in 1.01, 2, 5, 10, 

20, 50, and 100 years. The statistics were computed only for 

the 25 stations with periods of record of 10 years or more. 

The statistics were computed from records available through 

September 30, 2004 using standard methods and computer 

software developed by the USGS.

A comparison between low-flow frequency statistics 

computed for this study and for a previous study that used data 

available through September 30, 1989 was done for seven stations. The comparison indicated that, for the 7-day mean low 

flow, the newer values were 19.8 and 15.3 percent lower for 

the 20- and 10-year recurrence intervals, respectively, and 

2.1 percent higher for the 2-year recurrence interval, than the 

older values. For the 14-day mean low flow, the newer 20- and 

10-year values were 25.2 and 15.5 percent lower, respectively, 

and the 2-year value was 2.9 percent higher than the older 

values. For the 30-day mean low flow, the newer 20-, 10-, and 

2-year values were 10.8, 7.9, and 0.8 percent lower, respectively, than the older values. The newer values are generally 

lower than the older ones most likely because two major 

droughts have occurred since the older study was completed.

Introduction

Engineers, planners, land managers, biologists, and many 

others use streamflow statistics on a routine basis to help guide 

decision-making. Some uses of streamflow statistics include 

(1) flood-plain mapping for insurance underwriting and zoning, (2) bridge, culvert, and road design, (3) setting of waterquality standards, (4) water-supply planning and management, 

(5) wastewater-discharge permitting, and (6) protection of 

stream biota.

Streamflow statistics are computed for USGS streamgaging stations using the time series of discharge developed for 

the stations. Although the statistics are computed from actual 

data, they are considered estimates when they are used to represent long-term and future conditions for planning, management, and engineering purposes. This is because the statistics 

change over time as more data become available for use in the 

computations, and as extreme events influence the statistics. 

As a result, streamflow statistics for streamgaging stations 

should be updated periodically to reflect the longer record 

lengths available for the stations.

Low-flow and peak-flow statistics for streamgaging 

stations in Maryland were published previously in separate 

reports. Low-flow statistics for Maryland were last published 

by Carpenter and Hayes (1996). The statistics they published 

included the average 7-, 14-, and 30-consecutive-day low-flow 

discharges for recurrence intervals of 2, 10, and 20 years. 

Peak-flow statistics for Maryland were last published by 

Dillow (1996). The statistics published included the 2-, 5-, 

10-, 25-, 50-, 100-, and 500-year recurrence interval 

flood discharges.

The purposes of this report are to (1) provide updated 

streamflow statistics for 47 streamgaging stations in 

northeastern Maryland, (2) describe the methods used to 

determine the statistics, and (3) compare the low-flow 

frequency statistics provided in this report with those 

published previously by Carpenter and Hayes (1996). 

The statistics presented in this report include the mean, 

minimum, maximum, and standard deviation of the daily 

mean discharges for the periods of record at the stations, 

as well as flow-duration and low-flow frequency statistics. 

The flow-duration statistics give the percentage of time that 

Selected Streamflow Statistics for Streamgaging Stations 

in Northeastern Maryland, 2006

By Kernell G. Ries III
flows are equaled or exceeded, and include the 1-, 2-, 5-, 

10-, 15-, 20-, 25-, 30-, 40-, 50-, 60-, 70-, 75-, 80-, 85-, 90-, 

95-, 98-, and 99-percent duration discharges. The low-flow 

frequency statistics include the average discharges for 1, 7, 

14, and 30 days that recur, on average, once in 1.01, 2, 5, 10, 

20, 50, and 100 years. This report and the analyses described 

in it were done in cooperation with (1) the University of 

Maryland, Baltimore County, Center for Urban Environmental 

Research and Education; (2) the Baltimore City Department 

of Public Works; and (3) the Baltimore County Department 

of Environmental Protection and Resource Management. The 

statistics provided in this report were selected to indicate the 

range of streamflows occurring at the stations and to provide 

information that would be useful for water-supply planning 

and protection of water quality.

Physical Setting

The State of Maryland is in the Mid-Atlantic coastal 

region of the United States. The study area consists of all 

of Baltimore City, Baltimore and Harford Counties, and the 

eastern part of Carroll County that drains into Baltimore 

County. The area is bordered on the north by the State of 

Pennsylvania, on the west by the western part of Carroll 

County, on the southwest by Howard County, on the south by 

Anne Arundel County, on the southeast by the Chesapeake 

Bay, and on the northeast by Cecil County (fig. 1). Baltimore 

City has a land area of 81 mi2 (square miles) and the 

population was about 629,000 in 2003. Baltimore County has 

a land area of 599 mi2 and the population was about 777,000 

in 2003. Harford County has a land area of 440 mi2 and the 

population was about 232,000 in 2003. Carroll County has a 

land area of 449 mi2 and the population was about 163,000 in 

2003 (FedStats, 2006).

The climate in the study area is temperate. Mean annual 

precipitation ranges from about 40 to 44 inches (Carpenter and Hayes, 1996). The precipitation is distributed fairly 

evenly throughout the year. The mean annual temperature at 

Baltimore is 55°F (degrees Fahrenheit), with monthly averages ranging from 32°F in January to 77°F in July (National 

Oceanographic and Atmospheric Administration, 2005).

The study area is in two major physiographic provinces, 

the Coastal Plain and the Piedmont (Fenneman, 1938). The 

provinces are separated by the Fall Line, which crosses 

diagonally from the northeast corner of Maryland, through 

Baltimore (fig. 1), and beyond. The Fall Line, along which 

numerous waterfalls occur, delineates the relatively sudden 

drop in elevation from the Piedmont to the Coastal Plain. 

The Piedmont, northwest of the Fall Line, consists of gently 

rolling landscape with maximum elevations generally less 

than 400 ft (feet) above sea level. Streams in this province 

have fairly steep gradients, and drain to the Chesapeake Bay 

(Dillow, 1996). The Coastal Plain, southeast of the Fall Line, 

consists of an area of low relief adjacent to the Chesapeake 

Bay, with elevations ranging from sea level to less than 

100 ft. Streams in the Coastal Plain are often affected by tides 

for a substantial distance above their mouths. About 10 of 

the station locations are in the Coastal Plain, but most of the 

drainage areas for these stations are primarily in the Piedmont, 

and there are no apparent tidal effects.

Computation of Statistics

The low-flow frequency statistics presented in the report 

by Carpenter and Hayes (1996) were based on data through 

the 1989 water year. A water year begins on October 1 of the 

previous year and ends on September 30 of the given year. 

The 47 stations (fig. 1) selected for inclusion in this study 

were either active streamgaging stations at the end of the 2004 

water year (46 stations), or they were discontinued but had 

additional data since the previous report was released (station 

01585105). Periods of record for the stations ranged from 2 

to 78 years, with an average record length of 21 years. Daily 

mean discharges needed to compute the statistics were downloaded from the USGS NWIS-Web database. Surface-water 

data for the Nation can be accessed through NWIS-Web at 

http://waterdata.usgs.gov/nwis/sw.

Descriptive information for the streamgaging stations 

included in this study is presented in table 1. The information 

provided for each station includes station name, identification 

number, latitude, longitude, the city or county in which the 

station is located, drainage area, and remarks. As noted in the 

remarks, seven of the stations are affected to some extent by 

regulations, diversions, or both. As a result, the streamflow 

statistics computed for the affected stations do not reflect natural conditions. No attempt was made to adjust the streamflow 

records for the regulation patterns or to limit the periods of 

record for the analyses to unregulated periods.

Computer programs used to calculate the statistics were 

developed by the USGS, and can be downloaded from the web 

at no cost. The programs included ANNIE, which was used for 

binary database management; IOWDM, which was used for 

input and output of data to the database; and SWSTAT, which 

was used to compute the statistics presented in this report. The 

ANNIE program and accompanying documentation can be 

downloaded at http://water.usgs.gov/software/annie.html. The 

IOWDM program and accompanying documentation can be 

downloaded at http://water.usgs.gov/software/iowdm.html. The 

SWSTAT program and documentation for it can be downloaded at http://water.usgs.gov/software/swstat.html.

The SWSTAT program incorporates standard USGS 

methods for computing flow-duration and low-flow frequency 

statistics. Standard methods for computing flow-duration statistics were described in Searcy (1959). Standard methods for 

computing low-flow frequency statistics were described 

in Riggs (1972).

   Selected Streamflow Statistics for Streamgaging Stations in Northeastern Maryland, 2006
Figure 1. Locations of streamgaging stations in northeastern Maryland (including Baltimore City, Baltimore and Harford Counties, and 

a part of Carroll County).

Computation of Statistics 
Table 1. Summary of streamgaging stations in northeastern Maryland for which streamflow statistics were computed.—Continued

[Datum of latitude and longitude is North American Datum of 1983; drainage area is in square miles]

Station 

number Name Latitude Longitude Location Drainage area Remarks

01580000 Deer Creek at Rocks, MD 39.62997 -76.40331 Harford County 94.4 Low-flow regulation prior to 1965.

01580520 Deer Creek near Darlington, MD 39.61744 -76.19186 Harford County 16801581500 Bynum Run at Bel Air, MD 39.54147 -76.33011 Harford County 8.5201581700 Winters Run near Benson, MD 39.51994 -76.36914 Harford County 34.801581752 Plumtree Run near Bel Air, MD 39.49650 -76.34746 Harford County 2.5001581757 Otter Point Creek near Edgewood, MD 39.43928 -76.30603 Harford County 55.601581810 Gunpowder Falls at Hoffmanville, MD 39.68981 -76.78147 Baltimore County 27.001581830 Grave Run near Beckleysville, MD 39.65481 -76.78092 Baltimore County 7.6801581870 Georges Run near Beckleysville, MD 39.62589 -76.77253 Baltimore County 15.801581920 Gunpowder Falls near Parkton, MD 39.61889 -76.69031 Baltimore County 81.5 Upstream diversions and regulation.01581940 Mingo Branch near Hereford, MD 39.61125 -76.67522 Baltimore County 0.78 Slight diurnal fluctuation at low flow.01581960 Beetree Run at Bentley Springs, MD 39.67308 -76.67519 Baltimore County 9.7201582000 Little Falls at Blue Mount, MD 39.60408 -76.62047 Baltimore County 52.901582500 Gunpowder Falls at Glencoe, MD 39.54969 -76.63611 Baltimore County 160 Upstream diversions and regulation.01583100 Piney Run at Dover, MD 39.52061 -76.76689 Baltimore County 12.301583500 Western Run at Western Run, MD 39.51078 -76.67650 Baltimore County 59.801583570 Pond Branch at Oregon Ridge, MD 39.48031 -76.68750 Baltimore County 0.1201583580 Baisman Run at Broadmoor, MD 39.47947 -76.67803 Baltimore County 1.4701583600 Beaverdam Run at Cockeysville, MD 39.48558 -76.64572 Baltimore County 20.90158397967 Minebank Run at Glen Arm, MD 39.41011 -76.55608 Baltimore County 2.0601583980 Minebank Run at Loch Raven, MD 39.41667 -76.54631 Baltimore County 2.9001584050 Long Green Creek at Glen Arm, MD 39.45469 -76.47889 Baltimore County 9.4001584500 Little Gunpowder Falls at Laurel Brook, MD 39.50536 -76.43178 Baltimore County 36.101585090 Whitemarsh Run near Fullerton, MD 39.37958 -76.49581 Baltimore County 2.7301585095 North Fork Whitemarsh Run near White Marsh, MD 39.38589 -76.46886 Baltimore County 1.34

 Selected Streamflow Statistics for Streamgaging Stations in Northeastern Maryland, 2006
Table 1. Summary of streamgaging stations in northeastern Maryland for which streamflow statistics were computed.—Continued

[Datum of latitude and longitude is North American Datum of 1983; drainage area is in square miles]

Station 

number Name Latitude Longitude Location Drainage area Remarks

01585100 Whitemarsh Run at White Marsh, MD 39.37053 -76.44592 Baltimore County 7.61 Low-flow affected by sand and 

gravel plant.

01585104 Honeygo Run near White Marsh, MD 39.59111 -76.44083 Baltimore County 2.501585105 Honeygo Run at White Marsh, MD 39.37816 -76.42913 Baltimore County 2.6501585200 West Branch Herring Run at Idlewylde, MD 39.37364 -76.58433 Baltimore County 2.1301585225 Moores Run Tributary near Todd Avenue at Baltimore, MD 39.33669 -76.54061 Baltimore City 0.2101585230 Moores Run Tributary at Radeke Avenue at Baltimore, MD 39.33008 -76.53489 Baltimore City 3.5201585500 Cranberry Branch near Westminster, MD 39.59333 -76.96753 Carroll County 3.2901586000 North Branch Patapsco River at Cedarhurst, MD 39.50367 -76.88486 Carroll County 56.6 Numerous regulations and diversions.01586210 Beaver Run near Finksburg, MD 39.48944 -76.90294 Carroll County 14.001586610 Morgan Run near Louisville, MD 39.45189 -76.95531 Carroll County 28.001589000 Patapsco River at Holofield, MD 39.31031 -76.79242 Baltimore County 28501589100 East Branch Herbert Run at Arbutus, MD 39.24000 -76.69219 Baltimore County 2.4701589180 Gwynns Falls at Glyndon, MD 39.47169 -76.81689 Baltimore County 0.3201589197 Gwynns Falls near Delight, MD 39.44294 -76.78342 Baltimore County 4.2301589238 Gwynns Falls Tributary at McDonogh, MD 39.40044 -76.77044 Baltimore County 0.0301589300 Gwynns Falls at Villa Nova, MD 39.34589 -76.73319 Baltimore County 32.5 Slight regulations and diversions.01589330 Dead Run at Franklintown, MD 39.31122 -76.71664 Baltimore County 5.52 Occasional low-flow regulation.01589340 Rognel Heights Storm Sewer Outfall at Baltimore, MD 39.29986 -76.69014 Baltimore County 0.030158935180 Gwynns Run at Baltimore, MD 39.27825 -76.65169 Baltimore City 2.5001589352 Gwynns Falls at Washington Boulevard at Baltimore, MD 39.27150 -76.64856 Baltimore City 65.901589440 Jones Falls at Sorrento, MD 39.39172 -76.66094 Baltimore County 25.201589478 Jones Falls at Maryland Avenue at Baltimore, MD 39.30931 -76.61942 Baltimore City 58.3

Computation of Statistics 
Descriptive statistics, including means, minimums, maximums, and standard deviations, were computed from all available daily flow records for the stations, including incomplete 

water years. The mean streamflow is indicative of long-term 

normal conditions. The minimum and maximum streamflows 

are the extremes of daily streamflows during the period of 

record. The standard deviation is indicative of the variability 

of streamflows, as about two-thirds of all daily streamflows 

are within plus and minus one standard deviation value from 

the mean streamflow. The descriptive statistics are presented 

in table 2, along with the beginning and ending dates of available data and the number of days from which the statistics 

were calculated.

Flow-duration statistics indicate the percentage of time 

that daily mean streamflows are equaled or exceeded at the 

stations. For example, if the streamflow at the 90-percent 

duration is given for a station as 5 ft3/s (cubic feet per second), 

then the streamflow at that station was greater than or equal 

to 5 ft3/s 90 percent of the time during the period of record 

analyzed. The flow-duration statistics are presented in table 3, 

and were computed using data for only complete water years.

Low-flow frequency statistics indicate the magnitude 

and frequency of the occurrence of low streamflows at the 

streamgaging stations, and are useful for a variety of planning 

and design purposes. Low-flow frequency analyses were 

only done for the 25 stations in the study area with at least 

10 complete climatic years of record. Use of climatic years, 

which begin on April 1 of the given year and end on March 

31 of the following year, is standard practice for low-flow 

frequency analysis because low-flow periods occur most often 

in the summer and fall. Use of climatic years makes it highly 

unlikely that the lowest low-flow period in a given year will be 

split between 2 consecutive climatic years, as could sometimes 

happen if water years were used for this type of analysis.

Low-flow frequency statistics were computed for the 

25 stations from annual series of minimum n-day mean 

flows, where n = 1, 7, 14, and 30 days. For example, 

computing the annual series of minimum 7-day mean flows 

for a streamgaging station requires identifying the 7-day 

period during each climatic year with the lowest mean flow. 

Mann-Kendall nonparametric tests for monotonic trends in 

the annual 7-day low-flow series were done to determine if 

changes (increases or decreases) in the annual series were 

occurring over time (Helsel and Hirsch, 1992). No statistically 

significant trends were found.

The standard USGS method incorporated into SWSTAT 

for computing low-flow frequency statistics for a streamgaging 

station is to fit the logarithms of the annual n-day streamflows 

for the station to a log-Pearson, Type III frequency distribution 

to determine recurrence intervals (1.01, 2, 5, 10, 20, 50, and 

100 years) for the n-day streamflows. The streamflows equal 

to or less than those given for a specific recurrence interval 

can be expected to occur, on average, once during the time 

interval. For instance, the 7-day, 2- and 10-year recurrence 

interval flows were computed from annual series of minimum 

7-day average flows. Flows equal to or less than the 7-day, 

2-year flow occur on average once every 2 years, whereas 

flows equal to or less than the 7-day, 10-year flow occur on 

average once every 10 years. These flows have a 50 percent 

[(1 year/2 years) × 100] and 10 percent [(1 year/10 years) × 

100] chance of not being exceeded in any given year, respectively. The 1.01-year recurrence interval is given because it 

corresponds with the 99-percent chance of occurrence in any 

given year. The low-flow frequency statistics are presented in 

table 4.

The 7-day low-flow statistics are not available for West 

Branch Herring Run at Idlewylde, MD, station 01585200, 

because the computed skew of the logarithms of the annual 

7-day minimum flows was -3.73. The SWSTAT program does 

not compute low-flow frequencies when skew values exceed 

the absolute value of 3.3. The large negative skew at this station was caused primarily by the 2003 7-day low-flow value, 

which was only 0.001 ft3/s. On a logarithmic scale, the 2003 

value was more than an order of magnitude lower than the 

other values in the time series.

There is the potential that low-flow frequency statistics 

and improved flow-duration statistics could be estimated for 

many of the stations for which low-flow frequency statistics 

were not provided in this report because of record lengths 

that are less than 10 years. Correlations developed between 

the daily flows or n-day low flows at the short-term stations 

and those for nearby long-term stations could be used as a 

basis for extending or augmenting the records for the shortterm stations, enabling estimation of streamflow statistics that 

represent a longer-term period. Correlations such as these, 

however, were beyond the scope of this study.

   Selected Streamflow Statistics for Streamgaging Stations in Northeastern Maryland, 2006
Table 2. Descriptive statistics of the mean daily discharges for the period of record for streamgaging stations in northeastern 

Maryland.—Continued

[Mean, minimum, maximum, and standard deviation are in units of cubic feet per second]

Station 

number Mean Minimum Maximum Standard deviation Begin date End date Number of days

01580000 126 4.0 6,610 148 10/1/1926 9/30/2004 28,490

01580520 213 6.3 2,480 216 10/1/1999 9/30/2004 1,735

01581500 11.2 0.01 2,320 35.4 10/1/1943 9/30/2004 10,020

01581700 52.5 .38 3,000 78.0 8/1/1967 9/30/2004 13,576

01581752 4.49 .07 101 9.12 10/1/2001 9/30/2004 1,096

01581757 79.4 .27 1,760 136 1/1/2000 9/30/2005 2,058

01581810 34.9 2.0 536 38.1 5/1/2000 9/30/2004 1,614

01581830 10.3 .54 130 9.52 3/25/2000 9/30/2004 1,651

01581870 21.4 .95 353 25.4 3/25/2000 9/30/2004 1,651

01581920 107 12 1,000 87.6 7/17/2000 9/30/2004 1,535

01581940 0.99 0 28 1.21 10/1/1999 9/30/2004 1,827

01581960 13.7 1.1 290 16.0 10/1/1999 9/30/2004 1,827

01582000 68.9 4.5 4,730 77.7 7/1/1944 9/30/2004 22,007

01582500 207 31 4,500 187 10/1/1977 9/30/2004 8,943

01583100 14.6 .96 599 17.5 5/9/1982 9/30/2004 5,044

01583500 69.4 2.5 7,000 95.5 9/1/1944 9/30/2004 21,945

01583570 0.14 0 1.8 0.11 1/1/1983 9/30/2004 3,729

01583580 1.29 0 41 1.41 8/1/1964 9/30/2004 3,714

01583600 30.3 3.0 903 39.6 10/1/1982 9/30/2004 8,036

0158397967 3.25 .04 61 6.21 10/1/2001 9/30/2004 1,096

01583980 3.51 .13 150 6.59 10/1/1996 9/30/2004 2,922

01584050 11.3 .76 408 16.6 10/1/1975 9/30/2004 10,593

01584500 44.5 .90 2,800 65.9 11/1/1926 9/30/2004 18,232

01585090 5.16 0 418 15.2 1/1/1995 9/30/2004 3,561

01585095 2.22 0 140 5.95 4/17/1992 9/30/2004 4,545

01585100 12.3 .10 980 34.8 2/1/1959 9/30/2004 15,791

01585104 3.42 .02 74 6.90 10/1/1999 9/30/2004 1,827

01585105 3.84 .19 130 9.26 8/1/1990 9/30/1993 1,157

01585200 2.64 0 137 5.63 7/1/1957 9/30/2004 13,757

01585225 0.22 0 13 0.56 7/25/1996 9/30/2004 2,990

Computation of Statistics 
Table 2. Descriptive statistics of the mean daily discharges for the period of record for streamgaging stations in northeastern 

Maryland.—Continued

[Mean, minimum, maximum, and standard deviation are in units of cubic feet per second]

Station 

number Mean Minimum Maximum Standard deviation Begin date End date Number of days

01585230 4.19 .17 310 12.7 7/17/1996 9/30/2004 2,992

01585500 3.27 .01 440 6.58 10/1/1949 9/30/2004 20,089

01586000 64.9 .83 6,000 102 9/17/1945 9/30/2004 21,553

01586210 16.6 .27 528 20.4 10/1/1982 9/30/2004 8,036

01586610 34.7 .73 1370 49.1 10/1/1982 9/30/2004 8,036

01589000 196 5.9 30,000 407 5/17/1944 9/30/2004 19,694

01589100 3.34 .21 200 7.97 8/1/1957 9/30/2004 13,941

01589180 0.33 0 20 1.02 10/1/1998 9/30/2004 2,192

01589197 5.04 .25 161 10.4 10/1/1998 9/30/2004 2,192

01589238 0.03 0 0.9 0.05 10/1/1999 9/30/2004 1,827

01589300 40.1 1.7 5,000 89.4 2/1/1957 9/30/2004 14,487

01589330 8.03 .17 800 25.2 10/1/1959 9/30/2004 12,503

01589340 0.03 0 4.7 0.13 10/1/1998 9/30/2004 2,192

0158935180 8.81 .85 230 13.7 10/1/2001 9/30/2004 1,096

01589352 91.4 8.7 3,520 180 10/1/1998 9/30/2004 2,192

01589440 31.7 1.4 2,600 53.5 4/1/1966 9/30/2004 11,141

01589478 76.0 7.8 1,970 132 5/1/1981 9/30/2004 2,258

 Selected Streamflow Statistics for Streamgaging Stations in Northeastern Maryland, 2006
Table 3. Flow-duration statistics for streamgaging stations in northeastern Maryland.—Continued

Station 

number

Discharge, in cubic feet per second, exceeded given percentage of the time

99 98 95 90 85 80 75 70 60 50 40 30 25 20 15 10 5 2 1

01580000 25.2 28.9 35.6 43.7 50.9 57.1 62.9 68.7 81.5 96.2 111 134 145 165 191 217 299 489 724

01580520 14.6 20.3 36.3 56.4 67.1 77.9 89.7 101 133 169 205 249 273 298 341 403 558 815 118701581500 0.51 0.66 1.13 1.62 2.02 2.41 2.79 3.17 4.10 5.16 6.32 8.08 9.05 11.2 14.3 20.4 37.6 76.7 12701581649 2.36 2.44 2.70 3.12 3.59 4.09 4.58 5.49 7.11 8.39 10.1 12.8 15.0 17.3 20.3 24.9 36.8 132 23801581700 7.50 9.28 12.5 15.8 18.4 21.0 23.8 26.6 29.4 37.9 45.2 53.9 59.5 65.2 76.0 89.1 133 228 334

01581752 .14 .20 0.29 0.48 0.68 0.87 1.05 1.27 1.75 2.30 2.83 3.44 3.95 4.46 5.78 8.45 18.3 34.7 49.7

01581757 3.82 5.81 10.5 14.3 17.4 20.7 24.4 28.5 38.7 50.2 62.6 75.2 85.8 97.1 108 139 238 481 77801581810 2.38 3.46 6.46 9.50 11.0 12.6 14.5 16.5 21.4 27.3 33.5 40.4 44.8 49.2 54.9 67.5 92.0 141 195

01581830 .85 1.41 2.44 3.27 3.76 4.24 4.77 5.49 6.99 8.74 10.5 12.2 13.2 15.1 17.0 18.9 25.4 36.4 48.1

01581870 1.86 2.88 4.50 6.27 7.46 8.53 9.69 11.1 14.0 17.0 20.2 23.8 25.6 28.1 32.8 37.5 52.3 88.9 126

01581920 13.5 14.1 15.8 18.8 29.5 38.0 44.5 51.0 71.0 90.6 110 137 150 171 191 211 265 331 42801581940 .02 .04 .09 .19 .25 .30 0.35 0.41 0.57 0.78 1.05 1.31 1.44 1.57 1.80 2.06 2.41 3.18 4.09

01581960 1.87 2.35 3.70 4.77 5.3 5.83 6.36 7.06 8.72 11.0 13.5 16.0 17.2 18.5 21.1 24.6 31.9 51.2 78.8

01582000 13.8 16.2 20.6 24.8 28.6 31.7 34.9 38.0 45.4 52.7 63.6 74.7 84.0 94.5 105 125 163 245 34401582500 44.7 52.2 62.8 78.4 89.7 101 112 122 141 167 196 230 256 282 308 377 494 699 860

01583100 2.86 3.47 4.42 5.20 5.89 6.57 7.26 7.96 9.38 11.2 13.2 16.4 18.0 20.1 23.1 26.2 35.0 51.5 77.7

01583500 12.7 14.5 19.1 23.1 27.2 30.6 34.0 37.4 45.0 52.6 63.4 74.4 83.4 93.9 104 124 166 255 357

01583570 0 0 .01 .02 .04 .05 .06 .07 .09 .12 0.14 0.17 0.19 0.22 0.25 0.28 0.36 0.47 0.5501583580 .05 .10 .27 .42 .48 .54 .60 .67 .79 .99 1.22 1.47 1.59 1.91 2.23 2.73 3.28 4.47 6.17

01583600 5.70 6.79 8.24 10.3 12.2 13.7 14.9 16.2 18.7 22.0 25.4 30.5 34.0 37.4 44.7 52.9 79.7 134 193

0158397967 .03 .07 0.14 .26 .38 .51 .66 .83 1.2. 1.50 1.90 2.43 2.92 3.57 4.85 7.12 14.2 27.1 35.7

01583980 .29 .35 .46 .61 .71 .82 .97 1.13 1.43 1.83 2.36 3.16 3.71 4.35 5.45 7.15 12.3 22.8 32.401584050 1.65 2.04 2.61 3.27 3.81 4.34 4.93 5.57 6.86 8.25 9.78 11.8 12.8 14.7 16.7 18.8 26.8 51.8 79.4

01584500 6.71 8.44 12.2 15.2 17.7 20.0 22.1 24.3 28.6 33.2 37.8 45.6 49.6 54.4 64.7 75.0 107 181 270

01585090 .05 .11 .27 .40 .50 .62 .77 .97 1.30 1.59 2.04 2.69 3.15 4.06 5.87 11.1 23.2 47.8 71.4

Computation of Statistics   
Table 3. Flow-duration statistics for streamgaging stations in northeastern Maryland.—Continued

Station 

number

Discharge, in cubic feet per second, exceeded given percentage of the time

99 98 95 90 85 80 75 70 60 50 40 30 25 20 15 10 5 2 1

01585095 .02 .03 .08 .14 .18 .23 .28 .34 .48 .63 .80 1.15 1.45 1.93 2.86 5.08 11.0 21.2 30.201585100 .56 .71 1.10 1.47 1.78 2.06 2.35 2.68 3.34 4.22 5.39 6.97 8.38 10.5 14.9 24.1 50.6 105 16901585104 .03 .06 .14 .28 .42 .57 .71 .85 1.11 1.38 1.73 2.29 2.83 3.56 4.84 7.74 15.7 29.4 40.201585105 .22 .26 .32 .40 .53 .68 .84 1.03 1.37 1.73 2.14 2.92 3.48 4.24 5.34 6.98 12.8 31.6 46.601585200 .15 .21 .28 .39 .48 .57 .65 .72 .92 1.16 1.47 1.94 2.22 2.76 3.51 5.54 11.0 21.0 28.301585225 0 0 .01 .02 .02 .03 .04 .05 .07 .08 .10 .13 .16 .20 .32 .49 1.00 1.96 2.8501585230 .18 .22 .31 .42 .48 .54 .60 .68 .84 1.08 1.38 1.81 2.17 2.91 4.34 8.52 18.6 43.4 66.9

01585500 .22 .27 .36 .54 .80 1.11 1.31 1.51 1.88 2.24 2.74 3.27 3.75 4.26 5.00 6.17 8.94 15.9 22.701586000 10.3 12.7 15.3 19.3 22.2 25.1 28.1 31.3 37.6 45.5 54.0 67.5 74.2 86.0 99.6 119 171 283 407

01586210 2.36 2.72 3.64 4.78 5.56 6.33 7.15 7.98 9.85 12.5 15.4 18.4 20.6 23.4 26.3 32.7 44.5 66.7 92.0

01586610 3.46 4.84 6.84 9.00 10.7 12.4 14.1 15.8 19.4 24.1 29.7 36.9 42.2 48.3 55.9 69.6 97.2 144 203

01589000 18.3 21.7 29.4 39.1 47.5 55.7 63.8 71.8 91.1 113 143 190 216 264 321 414 597 970 1,31501589100 .36 .42 .51 .63 .72 .82 .97 1.11 1.31 1.51 1.82 2.22 2.60 3.10 4.05 6.17 12.8 25.8 37.4

01589180 0 0 .01 .02 .02 .03 .04 .04 .07 .11 .16 .22 .25 .30 .39 .66 1.30 2.90 4.80

01589197 .58 .76 1.10 1.32 1.55 1.72 1.88 2.03 2.38 2.92 3.52 4.27 4.69 5.47 6.25 8.1 13.8 31.6 55.3

01589238 0 0 .01 .01 .02 .02 .03 .03 .04 005 .06 .07 .08 .08 .09 .09 .10 .14 .23

01589300 4.57 5.48 7.51 9.87 11.6 13.4 14.9 16.4 19.6 23.6 27.9 34.5 37.8 44.7 51.9 70.6 122 238 36501589330 .32 .40 .52 .68 .82 1.00 1.16 1.31 1.62 2.06 2.63 3.47 4.31 5.8 8.92 16.4 36.2 75.1 113

01589340 0 0 .01 .01 .02 .02 .03 .03 .04 .05 .06 .07 .08 .09 .09 .10 .13 .27 .380158935180 .96 1.11 1.58 2.48 2.80 3.13 3.45 3.77 4.41 5.16 5.96 7.08 8.32 10.0 13.6 18.5 30.1 51.9 72.2

01589352 13.3 14.5 18.0 21.8 25.2 28.4 31.6 34.7 41.2 48.1 56.8 70.2 78.4 97.6 124 178 300 588 85701589440 3.88 5.21 7.24 9.28 10.8 12.3 13.8 15.5 18.7 22.6 26.7 32.8 35.9 40.2 46.7 53.8 76.1 141 217

01589478 9.98 12.3 16.3 20.5 23.2 26.0 28.9 32.0 38.1 45.8 53.8 67.3 74.0 87.8 105 138 219 460 684

10 Selected Streamflow Statistics for Streamgaging Stations in Northeastern Maryland, 2006
Table 4. Low-flow frequency statistics for streamgaging stations in northeastern Maryland.—Continued

[Discharges are in units of cubic feet per second]

Station 

number

Period of 

record

Number of 

days

Recurrence interval

100 50 20 10 5 2 1.01

01580000 1928–2004 1 7.0 9.4 14.1 19.4 27.0 43.7 74.8

7 8.6 11.4 16.7 22.5 30.6 48.0 79.0

14 10.2 13 18.3 23.9 31.9 49.6 90.2

30 15.3 18.1 22.8 27.8 34.9 51.7 118

01581500 1945–2004 1 0 0 0.1 0.2 0.4 1.2 2.5

7 0 0.1 .1 .2 .5 1.2 3.5

14 0.1 .1 .2 .3 .6 1.4 4.4

30 .4 .5 .6 .8 1.0 1.7 7.7

01581700 1968–2004 1 .6 1.1 2.5 4.6 8.2 16.4 23.9

7 .9 1.5 3.1 5.4 9.2 17.8 26.4

14 1.3 2.1 3.8 6.1 9.8 18.4 30.9

30 3.5 4.4 6.1 8.1 11.0 18.7 52.4

01582000 1945–2004 1 5.3 6.5 8.8 11.2 14.7 22.9 51.2

7 5.9 7.3 9.8 12.4 16.2 25.1 54.8

14 6.7 8.1 10.6 13.3 17.2 26.4 61.5

30 9.2 10.6 13.0 15.5 19.1 28.1 73.8

01582500 1979–2004 1 24.3 27.9 34.1 40.6 50.0 73.3 194

7 26.2 29.8 36.2 42.8 52.5 77.3 218

14 29.8 33.3 39.5 46.1 55.7 80.7 241

30 35.8 39.4 45.8 52.5 62.4 88.5 266

01583100 1983–2004 1 0.6 0.8 1.3 1.8 2.6 4.8 11.6

7 0.7 1.0 1.5 2.0 2.9 5.0 12.7

14 0.8 1.1 1.6 2.2 3.1 5.3 13

30 1.6 1.9 2.4 2.9 3.6 5.6 16.3

01583500 1945–2004 1 3.4 4.6 6.8 9.4 13.3 22.8 49.6

7 4.4 5.6 7.9 10.6 14.5 24.1 57.1

14 4.8 6.1 8.6 11.3 15.4 25.4 60.9

30 6.8 8.1 10.6 13.3 17.2 27.1 73.8

01583570 1984–2004 1 0 0 0 0 0 0 .2

7 0 0 0 0 0 0 .2

14 0 0 0 0 0 0 .3

30 0 0 0 0 0 .1 .2

01583580 1965–2004 1 0 0 0 0 0 .4 1.5

7 0 0 0 0 0 .4 1.6

14 0 0 0 0 0 .4 1.3

30 0 0 0 .1 .1 .4 2.4

Computation of Statistics 11
Table 4. Low-flow frequency statistics for streamgaging stations in northeastern Maryland.—Continued

[Discharges are in units of cubic feet per second]

Station 

number

Period of 

record

Number of 

days

Recurrence interval

100 50 20 10 5 2 1.01

01583600 1984–2004 1 2.9 3.3 4.1 4.9 6.1 9.1 23.9

7 3.6 4.1 4.9 5.7 7.0 10.1 28.3

14 4.1 4.6 5.4 6.3 7.5 10.6 29.8

30 5.6 6.0 6.8 7.5 8.7 12.0 38.8

01584050 1977–2004 1 .7 .9 1.1 1.4 1.9 3.1 10.5

7 .8 1.0 1.2 1.5 2.0 3.2 11.2

14 .9 1.1 1.3 1.7 2.1 3.4 11.6

30 1.1 1.3 1.6 1.9 2.4 3.7 13.9

01584500 1928–2004 1 1.4 2.2 3.8 5.7 8.7 15.2 23.4

7 1.8 2.6 4.3 6.3 9.4 16.2 25.8

14 2.2 3.0 4.8 6.9 9.9 16.9 29.6

30 3.4 4.4 6.2 8.2 11 17.9 39.3

01585095 1993–2004 1 0 0 0 0 0 .1 .5

7 0 0 0 0 0 .1 .8

14 0 0 0 0 .1 .1 .8

30 0 0 .1 .1 .1 .2 1.9

01585100 1960–2099 1 .1 .1 .2 .3 .5 .8 2.1

7 .2 .3 .4 .5 .6 1.0 3.1

14 .3 .4 .5 .6 .8 1.3 3.6

30 .6 .7 .8 1.0 1.2 1.8 6.6

01585200 1958–2004 1 0 0 .1 .1 .1 .2 1.0

7 Absolute value of skew is greater than 3.3. Estimates not computed.

14 .1 .1 .2 .2 .3 .4 1.3

30 .1 .2 .2 .3 .4 .6 1.6

01585500 1951–2004 1 0 0 .1 .1 .2 .6 1.4

7 0 0 .1 .2 .3 .8 1.7

14 .1 .1 .2 .2 .4 .9 2.4

30 .1 .1 .2 .3 .5 1.0 3.3

01586000 1946–2004 1 1.7 2.6 4.6 7.0 10.7 18.4 26.1

7 2.9 3.9 5.9 8.2 11.4 18.9 35.3

14 3.5 4.6 6.6 8.9 12.1 19.8 40.4

30 6.0 7.1 8.9 10.9 13.8 21.2 58.2

01586210 1984–2004 1 .2 .4 .8 1.2 2.0 4.1 8.3

7 .4 .5 .9 1.4 2.2 4.5 10.3

14 .5 .7 1.1 1.7 2.5 4.7 11.7

30 1.3 1.5 1.9 2.4 3.1 5.0 19.3

12 Selected Streamflow Statistics for Streamgaging Stations in Northeastern Maryland, 2006
Table 4. Low-flow frequency statistics for streamgaging stations in northeastern Maryland.—Continued

[Discharges are in units of cubic feet per second]

Station 

number

Period of 

record

Number of 

days

Recurrence interval

100 50 20 10 5 2 1.01

01586610 1984–2004 1 .7 1.0 1.6 2.5 3.9 7.9 21.8

7 .8 1.2 1.9 2.8 4.2 8.4 26.7

14 1.0 1.3 2.1 3.0 4.6 8.9 28.0

30 1.9 2.3 3.1 4.0 5.4 9.5 41.4

01589000 1945–2004 1 5.8 7.3 10.1 13.5 18.9 35.5 174

7 6.8 8.4 11.7 15.5 21.6 40.3 197

14 7.9 9.7 13.1 17.2 23.6 43.2 215

30 10.5 12.5 16.2 20.4 27.3 48.2 261

01589100 1958–2004 1 .2 .2 .3 .3 .4 .5 1.5

7 .2 .2 .3 .4 .4 .6 1.6

14 .2 .3 .3 .4 .5 .7 1.9

30 .3 .4 .4 .5 .6 .9 2.4

01589300 1958–2004 1 1.6 1.9 2.5 3.3 4.3 7.2 22.4

7 1.7 2.1 2.9 3.7 4.9 8.2 23.4

14 2.0 2.4 3.2 4.2 5.6 9.2 26.4

30 3.3 3.8 4.7 5.7 7.1 10.9 35

01589330 1961–2004 1 .1 .1 .2 .2 .3 .5 1.4

7 .2 .2 .2 .3 .4 .6 1.8

14 .2 .2 .3 .3 .4 .7 2.6

30 .2 .3 .3 .5 .6 1.1 3.8

01589440 1967–2004 1 1.4 1.8 2.5 3.3 4.6 7.8 22

7 1.4 1.8 2.6 3.6 5.0 8.7 23.6

14 1.5 1.9 2.8 3.8 5.3 9.4 25.8

30 2.3 2.8 3.7 4.7 6.2 10.3 32.9

01589478 1982–2004 1 3.5 4.2 5.7 7.3 9.9 17.5 75.8

7 3.5 4.4 6.0 7.9 10.9 19.3 73.2

14 3.7 4.5 6.2 8.1 11.2 19.9 83.4

30 11.1 11.5 12.4 13.5 15.6 23.1 196

Computation of Statistics 13
Comparison With Previously 

Published Statistics

Two significant droughts have occurred since the data for 

the previous study were analyzed; one that spanned the 1999 

and 2000 climatic years, and another that spanned the 2002 

and 2003 climatic years. Seventeen of the stations analyzed 

for this study have periods of record of 25 years or greater. Of 

these stations, the 2003 1-day and 7-day low flows were the 

lowest for the period of record for 10 stations, and the second 

lowest for 5 of them. The 2003 low flows were substantially 

lower than any previous low flows at most of the 10 stations. 

The 2000 1-day and 7-day low flows were the lowest for the 

period of record for two of the stations.

Low-flow frequency statistics for seven of the stations 

included in this study were published previously by Carpenter 

and Hayes (1996). As 15 years of additional data were available to analyze low-flow frequency statistics since the previous study was completed, and as substantial droughts have 

occurred since that study, it is useful to understand how this 

new information has affected the low-flow frequency analyses.

The new and previous estimates of the 7-, 14-, and 30-

day low flows for the 2-, 10-, and 20-year recurrence intervals 

for the seven stations, the percentage change in the statistics, 

and the average percentage change for each of the statistics are 

presented in table 5. The magnitude of the changes varies substantially among the stations, but the table generally indicates 

that the effects of the recent droughts on the low-flow frequency estimates increase with increasing recurrence interval. 

Changes in the 2-year recurrence interval estimates have been 

small, but the 10- and 20-year estimates have changed substantially at most stations.

The increase in percentage change with increasing 

recurrence interval can be partly explained by the fact that 

flow magnitude decreases with increasing recurrence interval. 

As the flow magnitude decreases, the percentage change for a 

given change in magnitude increases. For example, a change 

in flow of 0.1 ft3/s from a previous flow of 2.0 ft3/s is only a 

5-percent change, whereas a change in flow of 0.1 ft3/s from a 

previous flow of 0.2 ft3/s is a 50-percent change.

The addition of the two recent droughts to the annual 

low-flow time series probably accounts for most the changes 

in the low-flow statistics since the previous report. It is possible, however, that the changes are partly due to increased 

urbanization within the drainage basins for the stations. Some 

investigators have shown that increased urbanization can 

lead to decreased low flows in streams (U.S. Environmental 

Protection Agency, 2006). Much of the study area has been 

developing rapidly since the previous study was completed. 

Attempts to quantify the extent of change in urbanization and 

possible effects on low flows for the stations were beyond the 

scope of this study. The overall effect of the new computations 

is that generally there is less flow in the streams of Northeastern Maryland during times of drought than was thought to 

be available when the previous analysis was completed. As a 

result, State and local water-resource planners and managers 

may need to change their water-management plans and policies to accommodate the lower flows.

Summary

This report and the analyses it describes were done in 

cooperation with (1) the University of Maryland, Baltimore 

County, Center for Urban Environmental Research and 

Education; (2) the Baltimore City Department of Public 

Works; and (3) the Baltimore County Department of 

Environmental Protection and Resource Management. Means, 

minimums, maximums, and standard deviations of the mean 

daily discharges and flow-duration statistics were calculated 

for 47 streamgaging stations in northeastern Maryland. The 

flow-duration statistics include the 1-, 2-, 5-, 10-, 20-, 30-, 

40-, 50-, 60-, 70-, 80-, 90-, 95-, 98-, and 99-percent duration 

discharges. Low-flow frequency statistics were computed 

for 25 of the stations with periods of record of 10 or more 

years. The low-flow frequency statistics include the average 

discharges for 1, 7, 14, and 30 days that recur, on average, 

once in 1.01, 2, 5, 10, 20, 50, and 100 years. The statistics 

were computed using mean daily discharge data through 

September 30, 2004 and the U.S. Geological Survey ANNIE, 

IOWDM, and SWSTAT computer programs. The 7-day low 

flow annual series were tested for trends and none were found.

A comparison between low-flow frequency statistics 

computed for this study and for a previous study that used 

data available through September 30, 1989 was done for seven 

stations. The comparison indicated that, for the 7-day mean 

low flow, the newer values were 19.8 and 15.3 percent lower 

for the 20- and 10-year recurrence intervals, respectively, and 

2.1 percent higher for the 2-year recurrence interval, than the 

older values. For the 14-day mean low flow, the newer 20- and 

10- year values were 25.2 and 15.5 percent lower, respectively, 

and the 2-year value was 2.9 percent higher than the older 

values. For the 30-day mean low streamflow, the newer 20-, 

10-, and 2-year values were 10.8, 7.9, and 0.8 percent lower, 

respectively, than the older values. The newer values are lower 

than the older values most likely because of the occurrence 

of two major droughts since the older values were computed; 

however, it is also possible that increased urbanization within 

the drainage basins for the stations may be causing part of the 

reductions. The lower streamflows during times of drought 

may require State and local water-resource planners and managers to adjust their water-management plans and policies.

14  Selected Streamflow Statistics for Streamgaging Stations in Northeastern Maryland, 2006
Table 5. Comparison of low-flow frequency statistics computed from data available through climatic years 1989 and 2004 for 

streamgaging stations in northeastern Maryland with greater than 25 years of record.

[Discharges are in units of cubic feet per second]

Station 

number

20-year recurrence interval 10-year recurrence interval 2-year recurrence interval

2004

estimate

1989 

estimate

Percent 

change

2004

estimate

1989 

estimate

Percent 

change

2004

estimate

1989 

estimate

Percent 

change

7-day low flow

01580000 16.7 20.5 -18.5 22.5 25.4 -11.4 48 46.3 3.7

01581500 0.1 0.1 0.0 0.25 0.3 -16.7 1.2 1.3 -7.7

01581700 3.1 7.7 -59.7 5.37 8.9 -39.7 17.8 15.5 14.8

01582000 9.8 10.4 -5.8 12.4 13.1 -5.3 25.1 25.2 -0.4

01583500 8 8.4 -4.8 10.6 11 -3.6 24.1 23.7 1.7

01584500 4.3 6 -28.3 6.3 7.6 -15.8 16.2 15.2 6.6

01589440 2.6 3.3 -21.2 3.6 4.2 -14.3 8.73 9.1 -4.1

Average percent change -19.8 -15.3 2.1

14-day low flow

01580000 18.3 21.8 -16.1 23.9 26.7 -10.5 49.6 48.3 2.7

01581500 0.2 0.2 -50.0 0.3 0.4 -25.0 1.4 1.4 0.0

01581700 3.8 8.4 -54.8 6.1 9.6 -36.5 18.4 16.1 14.3

01582000 10.6 11.2 -5.4 13.3 14 -5.0 26.4 26.6 -0.8

01583500 8.6 9.1 -5.5 11.3 11.7 -3.4 25.4 24.9 2.0

01584500 4.8 6.4 -25.0 6.9 8.1 -14.8 16.9 16.2 4.3

01589440 2.8 3.5 -20.0 3.8 4.4 -13.6 9.4 9.6 -2.1

Average percent change -25.2 -15.5 2.9

30-day low flow

01580000 22.8 24.8 -8.1 27.8 29.6 -6.1 51.7 51.6 0.2

01581500 0.6 0.6 0.0 0.8 0.8 0.0 1.7 1.8 -5.6

01581700 6.1 9.6 -36.5 8.1 10.9 -25.7 18.7 18.1 3.3

01582000 13 13.1 -0.8 15.5 15.9 -2.5 28.1 28.4 -1.1

01583500 10.6 10.8 -1.9 13.3 13.4 -0.7 27.1 26.5 2.3

01584500 6.2 7.4 -16.2 8.2 9.2 -10.9 17.9 17.8 0.6

01589440 3.7 4.2 -11.9 4.7 5.2 -9.6 10.3 10.9 -5.5

Average percent change -10.8 -7.9 -0.8

Summary 15
References Cited

Carpenter, D.H., and Hayes, D.C., 1996, Low-flow characteristics of streams in Maryland and Delaware: U.S. Geological Survey Water-Resources Investigations Report 94–4020, 

113 p.

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

frequency of peak flows for Maryland: U.S. Geological 

Survey Water-Resources Investigations Report 95–4154, 

55 p.

FedStats, 2006, Maryland MapStats, accessed September 14, 

2006, at http://www.fedstats.gov/qf/states/24000.html

Fenneman, N.M., 1938, Physiography of the Eastern United 

States: New York, McGraw-Hill, 714 p.

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

water resources: New York, Elsevier, 326 p.

National Oceanographic and Atmospheric Administration, 

Northeast Regional Climate Center, 2005, Normal daily 

mean temperature, accessed on September 19, 2005, at 

http://www.nrcc.cornell.edu/ccd/nrmavg.html

Riggs, H.C., 1972, Low-flow investigations: U.S. Geological 

Survey Techniques of Water-Resources Investigations, 

book 4, chap. B3, 15 p.

Searcy, J.K., 1959, Flow-duration curves, manual of hydrology—part 2. Low flow techniques: U.S. Geological Survey 

Water-Supply Paper 1542-A, p. 1–33.

U.S. Environmental Protection Agency, 2006, Polluted 

runoff (nonpoint source pollution) appendix: case studies: 

accessed May 8, 2006, at http://www.epa.gov/owow/nps/

urbanize/appendix.html

16 Selected Streamflow Statistics for Streamgaging Stations in Northeastern Maryland, 2006
Prepared by Publishing Service Centers 3 and 1.

Edited by Valerie M. Gaine.

Graphics by Timothy W. Auer.

Layout by Ann Marie Squillacci.

For additional information, contact:

Director, MD-DE-DC Water Science Center

U.S. Geological Survey

8987 Yellow Brick Road

Baltimore, MD 21237

or visit our Web site at:

http://md.water.usgs.gov