U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2014–5170

Concentrations, Loads, and Yields of Total Phosphorus, 

Total Nitrogen, and Suspended Sediment and Bacteria 

Concentrations in the Wister Lake Basin, Oklahoma and 

Arkansas, 2011–13

Prepared in cooperation with the Poteau Valley Improvement Authority
Front cover:

Background, Wister Lake dam, Oklahoma, 2012.
Concentrations, Loads, and Yields of Total 

Phosphorus, Total Nitrogen, and Suspended 

Sediment and Bacteria Concentrations 

in the Wister Lake Basin, Oklahoma and 

Arkansas, 2011–13

By Stephanie D. Buck

Prepared in cooperation with the Poteau Valley Improvement Authority

Scientific Investigations Report 2014–5170

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2014

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Suggested citation:

Buck, S.D., 2014, Concentrations, loads, and yields of total phosphorus, total nitrogen, and suspended sediment and 

bacteria concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13: U.S. Geological Survey Scientific 

Investigations Report 2014–5170, 39 p., http://dx.doi.org/10.3133/sir20145170.

ISSN 2328-031X (print)

ISSN 2328-0328 (online)

ISBN 978-1-4113-3852-4 
iii

Acknowledgments

The author thanks many people for their contributions to the data collection presented in this 

report. Special thanks go to Waylon Marler for his efforts in collecting water samples in a wide 

range of conditions. The author also appreciates the helpful peer reviews by Anne Hoos of the 

U.S. Geological Survey (USGS) Tennessee Water Science Center and Jim Petersen of the USGS 

Arkansas Water Science Center. The author also appreciates the help of William Andrews, 

S. Jerrod Smith, and Stan Paxton of the USGS Oklahoma Water Science Center, the board 

members of the Poteau Valley Improvement Authority, and consultant Steven Patterson of Bio X 

Design for their suggestions and reviews of this report.

v

Contents

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

Introduction.....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................4

Study Area Description........................................................................................................................4

Streamflow in the Wister Lake Basin.........................................................................................................4

Methods...........................................................................................................................................................4

Water-Quality Data Collection and Analysis....................................................................................4

Estimation of Daily Streamflow for Ungaged Water-Quality Stations .........................................9

Streamflow Separation........................................................................................................................9

Load and Yield Estimation....................................................................................................................9

Assessment of Concentrations, Loads, and Yields of Total Phosphorus,

Total Nitrogen, and Suspended Sediment and Bacteria Concentrations

in the Wister Lake Basin ...............................................................................................................10

Concentrations....................................................................................................................................10

Total Phosphorus .......................................................................................................................12

Total Nitrogen .............................................................................................................................12

Suspended Sediment ................................................................................................................12

Bacteria.......................................................................................................................................16

Seasonal Variation of Concentration......................................................................................16

Estimated Annual Loads ....................................................................................................................16

Total Phosphorus .......................................................................................................................19

Total Nitrogen .............................................................................................................................19

Suspended Sediment ................................................................................................................20

Estimated Seasonal Loads ................................................................................................................20

Total Phosphorus .......................................................................................................................20

Total Nitrogen ............................................................................................................................21

Suspended Sediment ................................................................................................................21

Comparison of Estimated Annual Yields Among Stations............................................................22

Total Phosphorus .......................................................................................................................22

Total Nitrogen .............................................................................................................................23

Suspended Sediment ................................................................................................................26

Estimated Annual Flow-Weighted Mean Concentrations of Total Phosphorus

and Total Nitrogen.................................................................................................................26

Total Phosphorus .......................................................................................................................26

Total Nitrogen .............................................................................................................................27

Estimated Annual Total Phosphorus, Total Nitrogen, and Suspended Sediment

Loads Discharged into Wister Lake ...................................................................................27

Summary........................................................................................................................................................31

Selected References...................................................................................................................................32

Appendixes 1–3............................................................................................................................................35
vi

Figures

1. Map showing the Wister Lake Basin, Oklahoma and Arkansas, with

locations of selected real-time streamflow and water-quality data-collection

stations and towns with wastewater treatment plants that discharge

into streams in the basin, 2011–13 .............................................................................................3

2. Map showing the Wister Lake Basin, Oklahoma and Arkansas, with 2006

land cover and data-collection stations ...................................................................................5

3. Map showing the Wister Lake Basin, Oklahoma and Arkansas, and

water-quality stations and streamflow-gaging stations that produced data

used to compute streamflow for ungaged water-quality stations, 2011–13.......................7

4. Graphs showing streamflow separated into total flow, base flow, and

the times and flows at which water-quality samples were collected

at the water-quality stations in the Wister Lake Basin, Oklahoma and

Arkansas, 2010–13 ........................................................................................................................8

5. Graphs showing total phosphorus concentrations in water-quality

samples collected during base-flow and runoff conditions at the

water-quality stations in the Wister Lake Basin, Oklahoma and Arkansas,

October 2010 through September 2013 ...................................................................................13

6. Graphs showing total nitrogen concentrations in water-quality samples

collected during base-flow and runoff condtions at the water-quality

stations in the Wister Lake Basin, Oklahoma and Arkansas, October 2010

through September 2013............................................................................................................14

7. Graphs showing suspended sediment concentrations in water-quality

samples collected during base-flow and runoff condtions at the

water-quality stations in the Wister Lake Basin, Oklahoma and Arkansas,

October 2010 through September 2013 ...................................................................................15

8. Graphs showing total Escherichia coli bacteria concentrations in

water-quality samples collected during base-flow and runoff condtions

at the water-quality stations in the Wister Lake Basin, Oklahoma and

Arkansas, October 2010 through September 2013 ................................................................17

9. Graphs showing Enterococcus sp. bacteria concentrations in

water-quality samples collected during base-flow and runoff conditions

at the water-quality stations in the Wister Lake Basin, Oklahoma and

Arkansas, October 2010 through September 2013 ................................................................18
vii

Tables

1. Streamflow-gaging station information and streamflow statistics for the

water-quality stations sampled in the Wister Lake Basin, Oklahoma

and Arkansas, 2011–13 ................................................................................................................6

2. Summary statistics of total phosphorus, total nitrogen, suspended

sediment, Escherichia coli, and Enterococcus sp. concentrations in

water-quality samples collected during base-flow and runoff conditions

at water-quality stations in the Wister Lake Basin, Oklahoma and Arkansas,

October 2010 through September 2013 ...................................................................................11

3. Regression models used for estimating total phosphorus, total nitrogen,

and suspended sediment loads at water-quality stations sampled in the

Wister Lake Basin, Oklahoma and Arkansas, October 2010 to September 2013 .............19

4. Estimated annual total phosphorus loads and yields in the Wister

Lake Basin, Oklahoma and Arkansas, October 2010 through September 2013................20

5. Estimated annual total nitrogen loads and yields in the Wister Lake Basin,

Oklahoma and Arkansas, October 2010 through September 2013 .....................................21

6. Estimated annual suspended sediment loads and yields in the Wister

Lake Basin, Oklahoma and Arkansas, October 2010 through September 2013................22

7. Estimates of seasonal total phosphorus loads during base-flow and

runoff conditions in the Wister Lake Basin, Oklahoma and Arkansas,

October 2010 through September 2013 ...................................................................................23

8. Estimates of seasonal total nitrogen loads during base-flow and runoff

conditions in the Wister Lake Basin, Oklahoma and Arkansas, October

2010 through September 2013...................................................................................................24

9. Estimates of seasonal suspended sediment loads during base-flow and

runoff conditions in the Wister Lake Basin, Oklahoma and Arkansas,

October 2010 through September 2013 ...................................................................................25

10. Estimated annual total phosphorus loads, mean annual streamflows,

and flow-weighted mean total phosphorus concentrations at water-quality

stations in the Wister Lake Basin, Oklahoma and Arkansas, October 2010

through September 2013............................................................................................................26

11. Estimated annual total nitrogen loads, mean annual streamflows, and

flow-weighted mean total nitrogen concentrations at water-quality stations

in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through

September 2013...........................................................................................................................27

12. Estimated annual total phosphorus loads discharged to Wister Lake,

Oklahoma and Arkansas, October 2010 through September 2013 .....................................28

13. Estimated annual total nitrogen loads discharged to Wister Lake, Oklahoma

and Arkansas, October 2010 through September 2013 ........................................................29

14. Estimated annual total suspended sediment loads discharged to Wister

Lake, Oklahoma and Arkansas, October 2010 through September 2013...........................30
viii

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

mile, nautical (nmi) 1.852 kilometer (km)

Area

acre 4,047 square meter (m2)

acre 0.4047 hectare (ha)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

acre-foot (acre-ft) 1,233 cubic meter (m3)

Flow rate

acre-foot per day (acre-ft/d) 0.01427 cubic meter per second (m3/s)

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year (m3/yr)

cubic foot per second per square 

mile [(ft3/s)/mi2]

 0.01093 cubic meter per second per square 

kilometer [(m3/s)/km2]

cubic foot per day (ft3/d) 0.02832 cubic meter per day (m3/d)

Mass

ton, long (2,240 lb) 1.016 megagram (Mg) 

ton per day per square mile 

[(ton/d)/mi2]

 0.3503 megagram per day per square

kilometer [(Mg/d)/km2]

ton per year (ton/yr) 0.9072 megagram per year (Mg/yr)

ton per year (ton/yr) 0.9072 metric ton per year

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

°F=(1.8×°C)+32

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). The NAVD 88 replaced the National Geodetic Vertical Datum of 1929 (NGVD 29), 

previously known as the Sea Level Datum of 1929.

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.

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) 

or micrograms per liter (μg/L).
Concentrations, Loads, and Yields of Total Phosphorus, 

Total Nitrogen, and Suspended Sediment and Bacteria 

Concentrations in the Wister Lake Basin, Oklahoma and 

Arkansas, 2011–13

By Stephanie D. Buck

Abstract

The Poteau Valley Improvement Authority uses Wister 

Lake in southeastern Oklahoma as a public water supply. Total 

phosphorus, total nitrogen, and suspended sediments from 

agricultural runoff and discharges from wastewater treatment 

plants and other sources have degraded water quality in the 

lake. As lake-water quality has degraded, water-treatment cost, 

chemical usage, and sludge production have increased for the 

Poteau Valley Improvement Authority. 

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

with the Poteau Valley Improvement Authority, investigated 

and summarized concentrations of total phosphorus, total 

nitrogen, suspended sediment, and bacteria (Escherichia 

coli and Enterococcus sp.) in surface water flowing to 

Wister Lake. Estimates of total phosphorus, total nitrogen, 

and suspended sediment loads, yields, and flow-weighted 

mean concentrations of total phosphorus and total nitrogen 

concentrations were made for the Wister Lake Basin for a 

3-year period from October 2010 through September 2013. 

Data from water samples collected at fixed time increments 

during base-flow conditions and during runoff conditions at 

the Poteau River at Loving, Okla. (USGS station 07247015), 

the Poteau River near Heavener, Okla. (USGS station 

07247350), and the Fourche Maline near Leflore, Okla. 

(USGS station 07247650) water-quality stations were used 

to evaluate water quality over the range of streamflows in 

the basin. These data also were collected to estimate annual 

constituent loads and yields by using regression models. 

At the Poteau River stations, total phosphorus, total 

nitrogen, and suspended sediment concentrations in surfacewater samples were significantly larger in samples collected 

during runoff conditions than in samples collected during 

base-flow conditions. At the Fourche Maline station, in 

contrast, concentrations of these constituents in water samples 

collected during runoff conditions were not significantly 

larger than concentrations during base-flow conditions. Flowweighted mean total phosphorus concentrations at all three 

stations from 2011 to 2013 were several times larger than the 

Oklahoma State Standard for Scenic Rivers (0.037 milligrams 

per liter [mg/L]), with the largest flow-weighted phosphorus 

concentrations typically being measured at the Poteau River 

at Loving, Okla., station. Flow-weighted mean total nitrogen 

concentrations did not vary substantially between the Poteau 

River stations and the Fourche Maline near Leflore, Okla., 

station. At all of the sampled water-quality stations, bacteria 

(Escherichia coli and Enterococcus sp.) concentrations were 

substantially larger in water samples collected during runoff 

conditions than in water samples collected during base-flow 

conditions from 2011 to 2013. 

Estimated annual loads of total phosphorus, total 

nitrogen, and suspended sediment in the Poteau River stations 

during runoff conditions ranged from 82 to 98 percent of the 

total annual loads of those constituents. Estimated annual 

loads of total phosphorus, total nitrogen, and suspended 

sediment in the Fourche Maline during runoff conditions 

ranged from 86 to nearly 100 percent of the total annual loads.

Estimated seasonal total phosphorus loads generally 

were smallest during base-flow and runoff conditions in 

autumn. Estimated seasonal total phosphorus loads during 

base-flow conditions tended to be largest in winter and 

during runoff conditions tended to be largest in the spring. 

Estimated seasonal total nitrogen loads tended to be smallest 

in autumn during base-flow and runoff conditions and largest 

in winter during runoff conditions. Estimated seasonal 

suspended sediment loads tended to be smallest during baseflow conditions in the summer and smallest during runoff 

conditions in the autumn. The largest estimated seasonal 

suspended sediment loads during runoff conditions typically 

were in the spring.

The estimated mean annual total phosphorus yield was 

largest at the Poteau River at Loving, Okla., water-quality 

station. The estimated mean annual total phosphorus yield was 

largest during base flow at the Poteau River at Loving, Okla., 

water-quality station and at both of the Poteau River waterquality stations during runoff conditions. The estimated mean 

annual total nitrogen yields were largest at the Poteau River 
2 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

water-quality stations. Estimated mean annual total nitrogen 

yields were largest during base-flow and runoff conditions at 

the Poteau River at Loving, Okla., water-quality station. The 

estimated mean annual suspended sediment yield was largest 

at the Poteau River near Heavener, Okla., water-quality station 

during base-flow and runoff conditions.

Flow-weighted mean concentrations indicated that total 

phosphorus inputs from the Poteau River Basin in the Wister 

Lake Basin were larger than from the Fourche Maline Basin. 

Flow-weighted mean concentrations of total nitrogen did not 

vary spatially in a consistent manner. 

The Poteau River and the Fourche Maline contributed 

estimated annual total phosphorus loads of 137 to 278 tons per 

year (tons/yr) to Wister Lake. Between 89 and 95 percent of 

the annual total phosphorus loads were transported to Wister 

Lake during runoff conditions. The Poteau River and the 

Fourche Maline contributed estimated annual total nitrogen 

loads of 657 to 1,294 tons/yr, with 86 to 94 percent of the 

annual total nitrogen loads being transported to Wister Lake 

during runoff conditions. The Poteau River and the Fourche 

Maline contributed estimated annual total suspended sediment 

loads of 110,919 to 234,637 tons/yr, with 94 to 99 percent 

of the annual suspended sediment loads being transported 

to Wister Lake during runoff conditions. Most of the total 

phosphorus and suspended sediment were delivered to Wister 

Lake during runoff conditions in the spring. The majority of 

the total nitrogen was delivered to Wister Lake during runoff 

conditions in winter. 

Introduction

Wister Lake is the sole source of public water supplies 

for many residents and provides the water supply for all 

businesses in Le Flore County, Oklahoma (fig. 1) (Poteau 

Valley Improvement Authority, 2009). Wister Lake was 

constructed in 1949, and the Poteau Valley Improvement 

Authority (PVIA) began using the lake as a drinking water 

supply in 1969 (Poteau Valley Improvement Authority, 

2009). Estimated total daily water use for Le Flore County in 

2005 was about 20 million gallons per day, with most of the 

withdrawal of water in that county being for public supply 

(Tortorelli, 2009). Relatively large concentrations of total 

phosphorus, total nitrogen, and suspended sediment in the lake 

have caused it to become very turbid and eutrophic (containing 

increased amounts of algae and other aquatic plants caused by 

elevated concentrations of total phosphorus and total nitrogen) 

since a U.S. Environmental Protection Agency (EPA) survey 

was conducted in 1974 (Hession and others, 1996; Oklahoma 

Department of Environmental Quality, 2008). Wister Lake 

is cited in the Oklahoma Department of Environmental 

Quality (ODEQ) 2008 Section 303(d) of the Clean Water 

Act list of impaired water bodies because of relatively 

large concentrations of total phosphorus, total nitrogen, and 

suspended sediment. Such a listing requires that a Total 

Maximum Daily Load (TMDL) estimate be prepared for the 

lake (Oklahoma Department of Environmental Quality, 2008; 

Poteau Valley Improvement Authority, 2009). A TMDL is a 

calculation of the maximum amount of a pollutant that a water 

body can receive and still meet water-quality standards (U.S. 

Environmental Protection Agency, 2013). 

The mission of the PVIA is to produce and distribute 

potable water supplies to more than 40,000 customers through 

16 member municipalities and rural water districts (Poteau 

Valley Improvement Authority, 2009; U.S. Census Bureau, 

2012). The PVIA service region includes about 80 percent 

of Le Flore County, Okla. Deterioration of water quality in 

the lake has been caused by inflows of total phosphorus, total 

nitrogen, and suspended sediment from point and nonpoint 

sources surrounding and upstream of the lake (Oklahoma 

Department of Environmental Quality, 2008). Nonpoint 

sources can include runoff from agricultural areas, forests, dirt 

roads, and construction sites. Additionally, discharges from 

point sources such as wastewater-treatment (WWT) facilities 

and improperly functioning onsite wastewater treatment 

systems also may contribute total phosphorus and total 

nitrogen to the lake (Busteed and others, 2009; Poteau Valley 

Improvement Authority, 2009; U.S. Geological Survey, 1999). 

Deteriorating water quality in this lake has increased watertreatment costs, the amounts of treatment chemicals used, and 

production of sludge from water-treatment processes (Poteau 

Valley Improvement Authority, 2009). 

Elevated concentrations of total phosphorus, total 

nitrogen, suspended sediment, and bacteria are the most 

common sources of impairment of surface-water quality in the 

United States (U.S. Environmental Protection Agency, 2009). 

Determination of a TMDL requires estimation of the total load 

of a substance in a lake and contributions of those substances 

to a lake from nonpoint and point sources. To account for 

nonpoint sources contributing to the lake, water samples 

need to be collected during runoff conditions (Petersen and 

others, 2005). Other studies in basins in Oklahoma with 

similar land uses have shown that about 75 to 95 percent of 

total phosphorus and total nitrogen loads flow downstream 

during runoff conditions (Tortorelli, 2008; Andrews and 

others, 2009; Esralew and others, 2011). Fecal-indicator 

bacteria such as Escherichia coli and Enterococcus sp. also 

can seep in groundwater or be washed by runoff to streams 

from nonpoint and point sources. Mott and Steele (1991) 

reported that at the Buffalo River Basin in Arkansas, a single 

rain event can transport larger numbers of such bacteria from 

pastures into that river compared to base-flow conditions. 

Busteed and others (2009) described a study to identify 

critical source areas (CSAs) that contribute disproportionate 

pollutant loads to the lake, but the model used for that study 

was calibrated on the basis of nutrient concentrations from 

water samples that typically were collected during base-flow 

conditions (streamflow that occurs during relatively dry 

periods that is composed largely of groundwater seepage 

and treated wastewater from point-source discharges). 

Underrepresentation of samples collected during runoff 
laf14-0649_fig 01

Wister

Lake

Fourche Maline River Fourche Maline River

Poteau River

Poteau 

HASKELL

SEBASTIAN 

LE FLORE

LATIMER

POLK

PUSHMATAHA

OKLAHOMA

ARKANSAS

PITTSBURG

Heavener

Loving

Leflore

Red Oak

Page

Fourche Maline

07247650

Heavener

07247350

Loving

07247015

EXPLANATION

Wister Lake watershed boundary 

Data-collection station

Water-quality samplesReal-time streamflow

Studyarea

OKLAHOMA

ARKANSAS

0 5 

0 5 10 1

95°20' 95°10' 95° 94°50' 94°40' 94°30' 94°20' 94°10' 

35°10'35°34°50'34°40'

Base map modified from National Hydrography Dataset, 2006 National Land Cover Database (U.S. Geological Survey National Map 2013, watershed boundaries from StreamStats Web application 2013 and other digital data. Coordinate reference system: Albers Equal-Area Conic projection, horizontal datum is North American Datum 1983.

Figure 1. The Wister Lake Basin, Oklahoma and Arkansas, with locations of selected real-time streamflow and water-quality data-collection stationwastewater treatment plants that discharge into streams in the basin, 2011–13.
4 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

(also known as high-flow) conditions reduces the ability to 

reliably estimate concentrations and loads of constituents 

flowing down a stream during those conditions. Water-quality 

sampling conducted in this basin prior to the study described 

in this report did not include collection of notable numbers 

of surface-water samples at runoff conditions or analysis of 

suspended sediment and bacteria concentrations in water 

samples (Busteed and others, 2009).

Purpose and Scope

The purpose of this report is to describe concentrations, 

loads, and yields of total phosphorus, total nitrogen, and 

suspended sediment and concentrations of bacteria in the 

two principal tributaries of Wister Lake. This report provides 

annual estimates of total phosphorus, total nitrogen, and 

suspended sediment loads, yields, and flow-weighted mean 

(FWM) concentrations in the Poteau River and Fourche 

Maline from October 2010 through September 2013 (also 

known as water years 2011–13; a water year is the 12-month 

period October 1 through September 30 designated by the 

calendar year in which it ends). Load estimates by season 

and flow (base-flow versus runoff components) for the 3-year 

period also are presented for these constituents.

Total phosphorus, total nitrogen, suspended sediment, 

and bacteria (Escherichia coli and Enterococcus sp.) 

concentrations were compared for water samples collected by 

the U.S. Geological Survey (USGS) at three stations in the 

Wister Lake Basin. Those concentrations also were compared 

to Oklahoma State Standards for Scenic Rivers (State of 

Oklahoma, 2006) to flow-weighted concentrations measured 

mostly at undeveloped basins of the United States (Clark and 

others, 2000) and to Oklahoma State Standards for Primary 

Body Contact Recreation (State of Oklahoma, 2006). This 

report provides information needed to increase understanding 

of hydrology and water quality in the Wister Lake Basin and 

provides hydrologic data and interpretations that can be used 

to implement and enhance land-use and water-management 

policies for the Wister Lake Basin.

Study Area Description

Wister Lake in southeastern Oklahoma (fig. 1) receives 

inflows of water primarily from the Poteau River to the 

east and the Fourche Maline to the west. The Wister Lake 

Basin consists of approximately 930 square miles (mi2

) in 

southeastern Oklahoma and southwestern Arkansas. Wister 

Lake was constructed in 1949 by the U.S. Army Corps of 

Engineers (USACE) to provide flood control, water supply, 

flow regulation, and conservation (Poteau Valley Improvement 

Authority, 2009). The recreation opportunities Wister Lake 

provides are economically important for the surrounding area 

(Hession and others, 1996).

The study area surrounding Wister Lake Basin is about 

65 percent forest, 34 percent pasture and cropland, and 

1 percent urban (fig. 2; Multi-Resolution Land Characteristics 

Consortium, 2013). There were 1,428 cattle farms and 

316 poultry farms in this basin as of 2007 (U.S. Department 

of Agriculture, 2007). There are 2 municipal WWT facilities 

in Heavener that discharge into the Poteau River and 1 WWT 

facility that discharges into the Fourche Maline at Red Oak 

(fig.1). Streams receiving discharges of effluent from WWT 

facilities can have relatively large phosphorus and nitrogen 

concentrations during base-flow conditions in the Poteau 

River, whereas bacteria concentrations typically have been 

largest in nonpoint source runoff in this region (Petersen and 

others, 2005). 

Streamflow in the Wister Lake Basin

Streamflow in the Wister Lake Basin varied considerably 

during water years 2011–13 (table 1). The Poteau River, the 

primary stream that discharges to Wister Lake from the east, 

contributed the majority of the water flowing into the lake, 

with streamflow at particular sites increasing with upstream 

drainage area (table 1). Maximum daily streamflows for the 

study period were recorded in November 2011 at the Poteau 

River at Loving., Okla., water-quality station; in May 2013 at 

the Poteau River near Heavener, Okla., water-quality station; 

and in April 2011 at the Fourche Maline near Leflore, Okla., 

water-quality station (see Estimation of Daily Streamflow for 

Ungaged Water-Quality Stations section of this report) (fig. 3). 

Minimum recorded streamflows were zero flow, which were 

recorded at each of these three stations periodically during 

the 2011 and 2012 water years. At these stations, the largest 

monthly streamflows generally were measured from March 

to June, whereas the smallest monthly streamflows generally 

were measured from July through October (fig. 4).

Methods

Methods used for water-quality data collection and 

analysis, estimation of streamflow at ungaged stations, 

streamflow separation into base flow and runoff, statistical 

tests used to compare groups of data, and computation of 

statistics of phosphorus and nitrogen concentrations in the 

Wister Lake Basin from 2011 to 2013 are described in this 

section. Regression methods used to estimate phosphorus, 

nitrogen, and sediment loads and yields at selected stations

in this basin also are described.

Water-Quality Data Collection and Analysis

Water-quality data were collected at three stations: the 

USGS streamflow-gaging station Poteau River at Loving, 

Okla., (USGS station 07247015) and two ungaged waterquality stations, Poteau River near Heavener, Okla., (USGS 
laf14-0649_fig 02

Wister

Lake

Fourche Maline River Fourche Maline River

Poteau River

POLK

HASKELL

SEBASTIAN 

LATIMER

PUSHMATAHA

OKLAHOMA

ARKANSAS

PITTSBURG LE FLORE

Heavener

Loving

Leflore

Page

Fourche Maline

07247650

Heavener

07247350

Loving

07247015

EXPLANATION

Wister Lake watershed

boundary 

Data-collection station

Water-quality samplesReal-time streamflow

Studyarea

OKLAHOMA

ARKANSAS

Land cover, 2006

WaterUrbanDeciduous forestEvergreen forestMixed forest

Scrub/shrubGrasslandPasture and croplandCultivated cropsWetlands

0 5 1

0 5 10 15 

95°20' 95°10' 95° 94°50' 94°40' 94°30' 94°20' 94°10' 

35°10'35°34°50'34°40'

Base map modified from National Hydrography Dataset, 2006 National Land Cover Database (Multi-Resolution Land Characteristics Consortium, 2013) watershed boundaries from StreamStats Web application 2013 and other digital data. Coordinate reference system: Albers Equal-Area Conic projection, horizontal datum is North American Datum 1983.

Red Oak Poteau R

Figure 2. The Wister Lake Basin, Oklahoma and Arkansas, with 2006 land cover and data-collection stations.
6 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

Table 1. Streamflow-gaging station information and streamflow statistics for the water-quality stations sampled in the Wister Lake 

Basin, Oklahoma and Arkansas, 2011–13.

[ddmmss, degrees, minutes, seconds; mi2, square mile; ft3/s, cubic feet per second]

U.S. Geological Survey 

station name (number)

Latitude 

(ddmmss)

Longitude 

(ddmmss)

Upstream 

drainage 

area 

(mi2

)

Mean annual 

streamflow 

(ft3

/s)

Minimum and maximum daily 

mean streamflow for study period October 2010–September 2013 

(ft3

/s)

2011 2012 2013 Minimum 

(date)

Maximum 

(date)

Poteau River at

Loving, Okla. 

(07247015)

345247 942902 268 192.6 405.8 379.9 5 zero-flow days in 

2011, 11 zero-flow 

days in 2012

17,900 

(11/22/2011)

Poteau River near 

Heavener, Okla. 

(07247350)

345130 943745 515 415.0 846.7 911.0 5 zero-flow days in 

2011, 6 zero-flow 

days 2012

64,819 

(5/31/2013)

Fourche Maline near 

Leflore, Okla. 

(07247650)

345511 945643 267 265.9 232.9 281.7 3 zero-flow days in 

2011, 8 zero-flow 

days 2012

10,418 

(04/25/2011)

station 07247350) and Fourche Maline near Leflore, Okla., 

(USGS station 07247650), all of which are referred to in 

the remainder of this text as “stations” (fig. 1, table 1). 

The station on the Poteau River at Loving, Okla., was 

operated, and streamflows were measured according to 

methods described by Rantz and others (1982). At the 

ungaged stations on the Poteau River near Heavener, Okla., 

and the Fourche Maline near Leflore, Okla., streamflow 

measurements were made on the same dates as water-qualitysample collection in accordance with methods described by 

Rantz and others (1982).

Surface-water-quality data used for determining 

concentrations and estimating loads should be collected at a 

range of flow conditions (from low to high) in approximately 

equal numbers in all seasons (Tortorelli, 2008). Thirtysix water samples were collected from October 2010 to 

September 2013 at each of these three stations. Those 

samples were collected over wide ranges of streamflows 

and seasonal conditions (fig. 4). During each of the 3 years 

at each of these stations, 6 fixed-frequency water-quality 

samples per year were collected during low- to medianflow conditions, and 6 water-quality samples were sampled 

during higher flow (runoff) conditions. All of those samples 

were collected by using isokinetic equal-width incremental 

methods (Edwards and Glysson, 1999) which are designed 

to weight the amount of water collected across the width of 

a stream channel to include greater amounts from the faster 

flowing parts of stream cross sections. The water samples 

were sent to the USGS National Water-Quality Laboratory 

in Denver, Colorado, for analysis of concentrations of 

total phosphorus and total nitrogen. Water samples to be 

analyzed for suspended sediment concentration were sent 

to the USGS Iowa Sediment Laboratory in Iowa City, Iowa, 

at the beginning of water year 2011 and the USGS Missouri 

Sediment Laboratory in Rolla, Missouri, for the remainder of 

the study period. Bacteria concentrations were analyzed by 

USGS Tulsa (Okla.) Field Office personnel by using IDEXX® 

Colilert® for Escherichia coli concentrations and IDEXX ® 

Enterolert® for Enterococcus sp. concentrations, by following 

methods described in U.S. Geological Survey (2006), Harwell 

and Mobley (2009), and IDEXX Laboratories (2009).

U.S. Geological Survey protocols and procedures were 

followed for quality assurance (QA), as described in U.S. 

Geological Survey (2006). Collection of quality-control (QC) 

samples is a mandated USGS practice for water-quality field 

studies (U.S. Geological Survey, 2006) and is an important 

component of the quality assurance of this project. The goal 

of quality-assurance sampling is to identify, quantify, and 

document bias and variability in data that result from the 

collection, processing, shipping, and handling of samples. 

Field blanks and field sequential replicates were collected 

by the USGS at rates of 3 to 7 percent of the number of 

environmental samples collected. 

Three blank samples were collected at the Poteau 

River near Heavener station, with concentrations of all of 

the analyzed constituents in those samples being less than 

laboratory reporting levels. Additionally, numerous blank 

samples were analyzed for bacterial concentrations. Results 

of those analyses indicated little to no contamination during 

sampling or sample processing.
laf14-0649_fig 03

Wister

Lake

Fourche Maline River Fourche Maline River

Poteau River

HASKELL

SEBASTIAN 

LE FLORE

LATIMER

PUSHMATAHA

OKLAHOMA

ARKANSAS

PITTSBURG

Heavener

Loving

Page

Leflore

Red Oak

EXPLANATION

Wister Lake watershed boundary Subwatershed boundary 

Data-collection station

Water-quality samplesReal-time streamflow at streamflow-gaging station

Studyarea

OKLAHOMA

ARKANSAS

0 5 1

0 5 10 15 

95°20' 95°10' 95° 94°50' 94°40' 94°30' 94°20' 94°10' 

35°10'35°34°50'34°40'

Base map modified from National Hydrography Dataset, 2006 National Land Cover Database (U.S. Geological Survey National Map 2013 watershed boundaries from StreamStats Web application 2013 and other digital data. Coordinate reference system: Albers Equal-Area Conic projection, horizontal datum is North American Datum 1983.

Red Oak

07247500

Black Fork

07247250

Fourche Maline

07247650

Heavener

07247350

Loving

07247015 Poteau R

POLK

Figure 3. The Wister Lake Basin, Oklahoma and Arkansas, and water-quality stations and streamflow-gaging stations that produced data used to co

ungaged water-quality stations, 2011–13.
8 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

Base-flow water-quality sample

Runoff water-quality sample

Base flow

Total flow

Streamflow, in cubic feet per second

EXPLANATION

C. Poteau River near Heavener, Oklahoma

A. Poteau River at Loving, Oklahoma B. Fourche Maline near Leflore, Oklahoma

AJ F M M J

2012

AJ F M M J J A S O DN

2011

J A S O DN AJ F M M J

2013

J A S O DN

AJ F M M J

2012

AJ F M M J J A S O DN

2011

J A S O DN AJ F M M J

2013

J A S O DN

AJ F M M J

2012

AJ F M M J J A S O DN

2011

J A S O DN AJ F M M J

2013

J A S O DN

100

101

102

103

104

100

101

102

103

104

10-1

10-1

Figure 4. Streamflow separated into total flow, base flow, and the times and flows at which water-quality samples were collected 

at the (A) Poteau River at Loving, Oklahoma; (B) Fourche Maline near Leflore, Okla.; and (C) Poteau River near Heavener, Okla., waterquality stations in the Wister Lake Basin, Oklahoma and Arkansas, 2010–13.
Methods 9

Relative percent difference (RPD) was computed for 

analyzed concentrations between seven pairs of environmental 

and field sequential replicate samples (equation 1).

RPD = abs(D1-D2) / avg(D1+D2) x 100(1)

where

RPD = relative percent difference,

D1 = measured value of the first duplicate,

D2 = measured value of the second duplicate,

abs = absolute value of D1-D2, and

avg = mean value of D1 and D2.

The median RPDs between sequential replicates analyzed 

for phosphorus and nitrogen concentrations were 3.5 and 1.9, 

respectively. The median RPD in the sediment concentration 

was 11.8. Bacterial quantification was more variable, with the

median RPD for analyses of Escherichia coli being 21.1 and 

the median RPD for Enterococcus sp. being 28.6.

Estimation of Daily Streamflow for Ungaged 

Water-Quality Stations

Streamflow data at times other than sampling were not 

collected at two of the water-quality stations—Poteau River 

near Heavener, Okla., and Fourche Maline near Leflore, 

Okla.; however, streamflow data are required for computing 

annual and seasonal water-quality constituent loads with the 

S-LOADEST program (Cohn and others, 1989; Crawford, 

1991). Streamflow data were therefore estimated for these two 

stations by using data collected at nearby streamflow-gaging 

stations operated by the USGS (fig. 3). The Drainage-Area 

Ratio Method, which can be used to estimate flow at ungaged 

stations with upstream or downstream gages (Ries and Friesz, 

2000), was used to estimate daily flow data for the ungaged 

stations, as follows: 

Qs= [DAs/DA

g

] * Qg (2)

where

Qs = the daily mean streamflow at the ungaged 

station, in cubic feet per second;

DAs = the drainage area of the ungaged station, in 

square miles;

DAg = the drainage area of the gaging station 

(upstream or downstream), in square miles; 

and 

Qg = the daily mean streamflow at the gaging 

station (upstream or downstream) in cubic 

feet per second.

Daily mean streamflow at the Poteau River near 

Heavener, Okla., (fig. 3) was estimated by using the sum 

of daily streamflow at two upstream real-time streamflowgaging stations: Poteau River at Loving, Okla., (USGS station 

07247015) and Black Fork below Big Creek near Page, Okla. 

(USGS station 07247250). Daily mean streamflow for the 

Fourche Maline near Leflore, Okla., station was estimated by 

using the daily streamflow at the upstream station Fourche 

Maline near Red Oak, Okla. (USGS station 07247500) (fig. 3). 

Streamflow Separation

Streamflow data were separated into base-flow and runoff 

components by using a hydrograph-separation program, 

Base-Flow Index (Institute of Hydrology, 1980a, 1980b; 

Wahl and Wahl, 1988). Base flow is streamflow that occurs 

during dry periods and is largely composed of groundwater 

seepage (Langbein and Iseri, 1960). Base-flow and runoff 

components were separated because water-quality-constituent 

concentrations collected during base-flow conditions are 

more indicative of the effects of point-source discharges, and 

constituent concentrations collected during runoff conditions 

are more indicative of discharges from nonpoint sources, 

with separation being useful for developing understanding of 

potential sources of these constituents (Tortorelli, 2008). By 

using the Base-Flow Index program, the minimum daily flow 

was identified in consecutive 5-day increments, and minimums 

smaller than 90 percent of adjacent minimums were defined 

as turning points (Wahl and Tortorelli, 1997). The Base-Flow 

Index program computes estimates of the base-flow hydrograph 

by connecting straight lines through consecutive turning points. 

Runoff components were calculated as the difference between 

total streamflow and the base-flow component.

Load and Yield Estimation

Load is the amount of a constituent transported past a 

given point of a stream per period of time, expressed in units 

of mass per unit of time. Instantaneous load can be computed 

as the product of instantaneous streamflow (Q) and an 

instantaneous constituent concentration in water (C) multiplied 

by a conversion factor to convert cubic feet per second (ft3

/s) 

and milligrams per liter (mg/L) into mass per unit of time. 

Similarly, seasonal or annual load can be computed as the 

product of seasonal or annual mean Q and seasonal or annual 

mean C if measured, but seasonal and annual mean C were not 

measured in this study because water-quality samples were only 

collected periodically. Linear regression was used, therefore, 

to estimate daily, seasonal, and annual mean constituent loads 

(total phosphorus, total nitrogen, and suspended sediment) from 

the periodically collected water-quality data and daily mean 

streamflow data. Constituent load is the dependent variable, 

and streamflow and time are the independent variables in 

such regressions. Regression methods require that daily mean 

streamflow and data from discrete water-quality samples be 

collected for several years (Runkel and others, 2004). Sample 

dates, times, continuous streamflow data, and total phosphorus, 

total nitrogen, and suspended sediment concentrations used in 

the regression analyses are provided in appendixes 1–3.
10 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

The S-LOADEST program was used to fit parameters for 

linear regressions between constituent load and independent 

variables and then to estimate constituent loads at the 

sampled stations (Cohn and others, 1989; Crawford, 1991). 

S-LOADEST is based on the LOADEST program (Runkel 

and others, 2004) and has been incorporated in the statistical 

computer program S-Plus (Insightful Corporation, 2005) 

by the USGS to aid in graphical analysis and production of 

tabular results. S-LOADEST provides several options (for 

example, adjusted maximum likelihood method, least absolute 

deviation, Beale’s ratio estimator) for applying regressions. 

Because the sample dataset for each constituent contained 

censored data (censored values are the values of the lower 

reporting level, reported with a “less than” remark code for 

samples in which the concentration was not detected), the 

adjusted maximum likelihood method was selected to estimate 

values of censored data for model computation (Dempster and 

others, 1977). 

 S-LOADEST contains nine predefined rating-curve 

models that can be used to test relations between constituent 

load and streamflow. For this study, two of the model 

equations were used. The first model (equation 3) was used 

to estimate loads of total phosphorus and total nitrogen and 

includes seasonality variables to simulate the relation between 

the natural logarithms of L and Q:

 ln(L) = a0+a1

*

lnQ+a2

*

sin SS+a3

*

cos SS (3)

where

ln = natural logarithm;

L = constituent load, in tons per day;

a0, a1, a2, a3 = regression coefficients, dimensionless;

Q = daily streamflow, in cubic feet per second;

sin = sine;

cos = cosine; and

SS = seasonality parameter (2*pi*dectime, the 

time parameter in decimal years).

The second model (equation 4) was used to estimate 

loads of suspended sediment and simulates the relation 

between the natural logarithms of L, Q, and Q2

:

ln(L) = a0+a1

*

lnQ+a2

*

lnQ2 (4)

where

ln = natural logarithm;

L = constituent load, in tons per day;

a0, a1, a2 = regression coefficients, dimensionless; and

Q = daily streamflow, in cubic feet per second.

Estimated annual total phosphorus, total nitrogen, and 

suspended sediment loads and estimates of the standard 

deviations of the loads were calculated with S-LOADEST 

by using all data from water samples collected during baseflow and runoff conditions. The daily load values generated 

by S-LOADEST were separated into base-flow and runoff 

component sample sets according to the number of baseflow and runoff days for each water year (October 1 through 

September 30). Estimated annual base-flow loads were 

calculated as the sum of the values of the base-flow days 

sample sets. Estimated annual runoff loads were calculated 

as the sum of the values of the runoff days sample sets. The 

estimates of annual runoff load were biased slightly high, and 

the corresponding estimates of base-flow load were biased 

slightly low because a small fraction of the load on runoff 

days is from base flow, but because that fraction is small, the 

bias can be considered negligible. Estimated seasonal baseflow and runoff loads were calculated in the same manner, on 

the basis of the number of base-flow and runoff days in each 

season. In this report, the seasons are described as follows: 

(1) spring is March through May, (2) summer is June through 

August, (3) autumn is September through November, and 

(4) winter is December through February. Yields of total 

phosphorus, total nitrogen, and suspended sediment for the 

study period at each station were calculated by dividing annual 

loads of total phosphorus, total nitrogen, and suspended 

sediment by upstream drainage-basin area. 

Assessment of Concentrations, Loads, 

and Yields of Total Phosphorus, Total 

Nitrogen, and Suspended Sediment 

and Bacteria Concentrations in the

Wister Lake Basin

In this section, concentrations, loads, and yields of 

total phosphorus, total nitrogen, and suspended sediment 

are described for the three sampled stations in the Wister 

Lake Basin for water years 2011–13. Bacteria (Escherichia 

coli and Enterococcus sp.) concentrations collected during 

base-flow and runoff conditions also are described. All annual 

and seasonal loads, yields, and concentrations are based on 

estimated daily values of those statistics calculated by using 

the S-LOADEST program.

Concentrations

This section describes total phosphorus, total nitrogen, 

suspended sediment, and bacteria (Escherichia coli and 

Enterococcus sp.) concentrations in water-quality samples 

collected during base-flow and runoff conditions. Summary 

statistics of those data were computed for all samples collected 

from water years 2011 through 2013 and were divided into 

samples collected during base-flow and runoff conditions 

(table 2). For constituent results with censored data (marked 

with a less than symbol [<]), a distributional method called 

the maximum likelihood method (MLE) was used to estimate 

summary statistics (Helsel and Hirsch, 1992). Total nitrogen 

concentration and bacteria concentrations were the only 
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin Assessment of Concentrations in the Wister Lake Basin 11

Table 2. Summary statistics of total phosphorus, total nitrogen, suspended sediment, Escherichia coli, and Enterococcus sp. 

concentrations in water-quality samples collected during base-flow and runoff conditions at water-quality stations in the Wister Lake 

Basin, Oklahoma and Arkansas, October 2010 through September 2013.

[obs., number of observations; mg/L, milligrams per liter; mL, milliliters; <, less than; >, greater than]

Station name 

(number)

Base-flow concentrations

obs.

Runoff concentrations

obs. Minimum Median Mean Maximum Minimum Median Mean Maximum

Total phosphorus

(mg/L as P)

Total phosphorus

(mg/L as P)

Poteau River at Loving, Okla. 

(07247015)

0.043 0.055 0.065 0.152 17 0.06 0.279 0.273 0.461 18

Poteau River near Heavener, 

Okla. (07247350)

0.023 0.05 0.056 0.114 15 0.051 0.205 0.196 0.378 22

Fourche Maline near 

Leflore, Okla. (07247650)

0.04 0.069 0.069 0.096 11 0.034 0.142 0.176 0.717 24

Station name

(number)

Base-flow concentrations

obs.

Runoff concentrations

obs. Minimum Median Mean Maximum Minimum Median Mean Maximum

Total nitrogen

(mg/L as N)

Total nitrogen

(mg/L as N)

Poteau River at Loving, Okla. 

(07247015)

0.43 0.59 0.65 1.1 17 0.53 1.3 1.1 2.4 18

Poteau River near Heavener, 

Okla. (07247350)

0.36 0.57 0.65 1.2 15 0.5 1.1 1.1 1.7 22

Fourche Maline near 

Leflore, Okla. (07247650)

0.52 0.71 0.82 1.7 11 0.45 1.0 1.1 2.5 24

Station name

(number)

Base-flow concentrations

obs.

Runoff concentrations

obs. Minimum Median Mean Maximum Minimum Median Mean Maximum

Suspended sediment

(mg/L )

Suspended sediment

(mg/L)

Poteau River at Loving, Okla. 

(07247015)

3 11 11 28 16 10 84 134 554 16

Poteau River near Heavener, 

Okla. (07247350)

3 14 14 28 14 11 86 148 658 20

Fourche Maline near 

Leflore, Okla. (07247650)

9 27 33 71 10 10 74 146 820 20

Station name

(number)

Base-flow concentrations

obs.

Runoff concentrations

Minimum Median Mean Maximum Minimum Median Mean Maximum obs.

Escherichia coli per 100 mL of water Escherichia coli per 100 mL of water

Poteau River at Loving, Okla. 

(07247015)

<10 52 69 310 13 120 3,100 4,253 14,000 18

Poteau River near Heavener, 

Okla. (07247350)

<10 26 54 250 14 41 2,050 2,443 9,900 22

Fourche Maline near 

Leflore, Okla. (07247650)

<10 52 120 490 10 10 1,085 3,179 24,000 24
12 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

conditions at the Fourche Maline near Leflore, Okla., station 

generally were larger than concentrations in the water 

samples collected at the Poteau River stations during baseflow conditions. The smallest total nitrogen concentration of 

0.36 mg/L measured at base-flow conditions was measured in 

a water sample collected at the Poteau River near Heavener, 

Okla., station, and the smallest total nitrogen concentration 

of 0.45 mg/L was measured at runoff conditions in a water 

sample collected at the Fourche Maline near Leflore, Okla., 

station (table 2). The largest total nitrogen concentration at 

base-flow conditions (1.7 mg/L) and the largest total nitrogen 

concentration at runoff conditions (2.5 mg/L) were measured 

in water samples collected at the Fourche Maline near Leflore, 

Okla., station (table 2).

Suspended Sediment

Suspended sediment concentrations (fig. 7, table 2) were 

significantly larger (p≤0.05) in water samples collected during 

runoff conditions than in water samples collected at baseflow conditions at all stations except at the Fourche Maline 

station during the 3-year study period. Suspended sediment 

concentrations in water samples collected at base-flow 

conditions at the Fourche Maline near Leflore, Okla., station 

generally were larger than in water samples collected during 

base-flow conditions at the Poteau River stations.

The smallest suspended sediment concentration in water 

samples collected during base-flow conditions (3 mg/L) 

was measured in water samples collected at the Poteau 

River stations (table 2). The smallest suspended sediment 

concentration in water samples collected during runoff 

conditions (10 mg/L) was measured in a water sample 

collected at the Poteau River at Loving, Okla., and the 

Fourche Maline near Leflore, Okla., stations. The smallest 

suspended sediment concentration in water samples collected 

during runoff conditions was only slightly larger at the Poteau 

River near Heavener, Okla., station (11 mg/L). The largest 

Table 2. Summary statistics of total phosphorus, total nitrogen, suspended sediment, Escherichia coli, and Enterococcus sp. 

concentrations in water-quality samples collected during base-flow and runoff conditions at water-quality stations in the Wister Lake 

Basin, Oklahoma and Arkansas, October 2010 through September 2013.—Continued

[obs., number of observations; mg/L, milligrams per liter; mL, milliliters; <, less than; >, greater than]

Station name

(number)

Base-flow concentrations

obs.

Runoff concentrations

obs.

Minimum Median Mean Maximum Minimum Median Mean Maximum

Enterococcus sp. colonies per 100 mL of water Enterococcus sp. colonies per 100 mL of water

Poteau River at Loving,

Okla. (07247015)

13 260 978 >4,800 13 40 4,800 3,424 >4,800 18

Poteau River near Heavener, 

Okla. (07247350)

4 18 72 500 14 <2 3,200 2,706 >4,800 22

Fourche Maline near 

Leflore, Okla. (07247650)

32 74 153 820 10 27 1,750 2,170 >4,800 24

constituents with censored data. The Wilcoxon rank-sum test 

was used to determine statistical significance of differences 

between samples collected during base-flow conditions and 

samples collected during runoff conditions, with significant 

differences in locations of distribution of datasets in this report 

being indicated by p-values <0.05 (Helsel and Hirsch, 1992).

Total Phosphorus

Total phosphorus concentrations in water samples 

collected during runoff conditions (fig. 5, table 2) were 

significantly larger (p≤0.05) than concentrations in samples 

collected during base-flow conditions at all stations except 

Fourche Maline for the 3-year study period. The smallest 

base-flow concentration of total phosphorus of 0.023 mg/L 

was measured in a water sample collected at the Poteau 

River near Heavener, Okla., station (table 2). The smallest 

total phosphorus concentration of 0.034 mg/L during runoff 

conditions was measured in a water sample collected at the 

Fourche Maline near Leflore, Okla., station. The largest 

total phosphorus concentration collected during base-flow 

conditions of 0.152 mg/L was measured in a water sample 

collected at the Poteau River at Loving, Okla., station, and 

the largest total phosphorus concentration of 0.717 mg/L 

collected during runoff conditions was measured in a water 

sample collected at the Fourche Maline near Leflore, Okla., 

station (table 2). 

Total Nitrogen

Total nitrogen concentrations measured in water samples 

collected during runoff conditions (fig. 6, table 2) were 

significantly larger (p≤0.05) than total nitrogen concentrations 

in water samples collected during base-flow conditions 

at all stations except at the Fourche Maline near Leflore, 

Okla., station during the 3-year study period. Total nitrogen 

concentrations in water samples collected during base-flow 
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin 13

laf14-0649_fig 05

EXPLANATION

Base-flow phosphorus concentration

2011

2012

2013

2011

2012

2013

Runoff phosphorus concentration

Oklahoma Scenic Rivers water-quality standard

of 0.037 milligrams per liter of phosphorus

(State of Oklahoma, 2006)

C. Poteau River near Heavener, Oklahoma

A. Poteau River at Loving, Oklahoma B. Fourche Maline near Leflore, Oklahoma

Total phosphorus, in milligrams per liter as phosphorus

10-1 100 101 102 103 104 105

Streamflow, in cubic feet per second

10-1 100 101 102 103 104 105

Streamflow, in cubic feet per second

10-1 100 101 102 103 104 105

Streamflow, in cubic feet per second

0.0

0.1

0.2

0.3

0.4

0.5

0.0

0.1

0.2

0.3

0.4

0.5

Figure 5. Total phosphorus concentrations in water-quality samples collected during base-flow and runoff conditions at the (A) Poteau 

River at Loving, Oklahoma; (B) Fourche Maline near Leflore, Okla.; and (C) Poteau River near Heavener, Okla., water-quality stations in 

the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through September 2013.

Assessment of Concentrations in the Wister Lake Basin
14 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

laf14-0649_fig 06 Total nitrogen, in milligrams per liter as nitrogen

C. Poteau River near Heavener, Oklahoma

A. Poteau River at Loving, Oklahoma B. Fourche Maline near Leflore, Oklahoma

10-1 100 101 102 103 104 105 10-1 100 101 102 103 104 105

10-1 100 101 102 103 104 105

EXPLANATION

0

0.5

1.0

1.5

2.0

3.0

2.5

0

0.5

1.0

1.5

2.0

3.0

2.5

Streamflow, in cubic feet per second Streamflow, in cubic feet per second

Streamflow, in cubic feet per second

Base-flow nitrogen concentration

2011

2012

2013

2011

2012

2013

Runoff nitrogen concentration

Figure 6. Total nitrogen concentrations in water-quality samples collected during base-flow and runoff conditions at the (A) Poteau 

River at Loving, Oklahoma; (B) Fourche Maline near Leflore, Okla.; and (C) Poteau River near Heavener, Okla., water-quality stations in 

the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through September 2013.
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin 15

laf14-0649_fig 07

C. Poteau River near Heavener, Oklahoma

A. Poteau River at Loving, Oklahoma B. Fourche Maline near Leflore, Oklahoma

10-1 100 101 102 103 104 105 10-1 100 101 102 103 104 105

10-1 100 101 102 103 104 105

EXPLANATION

0

200

400

600

800

0

200

400

600

800

Streamflow, in cubic feet per second Streamflow, in cubic feet per second

Streamflow, in cubic feet per second

Suspended sediment concentration, in milligrams per liter

Base-flow sediment concentration

2011

2012

2013

2011

2012

2013

Runoff sediment concentration

Figure 7. Suspended sediment concentrations in water-quality samples collected during base-flow and runoff conditions at the (A) 

Poteau River at Loving, Oklahoma; (B) Fourche Maline near Leflore, Okla.; and (C) Poteau River near Heavener, Okla., water-quality 

stations in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through September 2013.

Assessment of Concentrations in the Wister Lake Basin
16 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

suspended sediment concentration measured in water samples 

collected at base-flow conditions (71 mg/L) and the largest 

suspended sediment concentration in water samples collected 

during runoff conditions (820 mg/L) were in samples collected 

at the Fourche Maline near Leflore, Okla., station (table 2).

Bacteria

Concentrations of Escherichia coli (fig. 8, table 2) were 

significantly larger (p≤0.05) in water samples collected during 

runoff conditions than during base-flow conditions at these 

three stations. In water samples collected during base-flow 

conditions, Escherichia coli bacteria concentrations decreased 

in the downstream direction (Loving to Heavener, Okla.) at 

the two Poteau River stations. At the Fourche Maline near 

Leflore, Okla., station, bacteria concentrations collected 

during base-flow conditions were not significantly larger 

(p is greater than [>] 0.05) than concentrations measured 

in water samples collected in base-flow conditions at the 

Poteau River stations. In water samples collected during 

runoff conditions, Escherichia coli concentrations decreased 

in the downstream direction (Loving to Heavener) in water 

samples collected at the Poteau River stations. During runoff 

conditions, Escherichia coli bacteria concentrations generally 

were larger in water samples collected at the Poteau River 

stations than at the Fourche Maline near Leflore, Okla., 

station. The smallest Escherichia coli bacteria concentration 

in water samples collected at all stations during base-flow 

conditions was smaller than the detection limit (<10 colonies 

per 100 milliliters [mL], table 2). During base-flow conditions, 

the largest Escherichia coli bacteria concentration (490 

colonies per 100 mL) was measured in a water sample 

collected at the Fourche Maline near Leflore, Okla., station. 

That concentration of Escherichia coli bacteria was larger 

than the Oklahoma State Standard for Primary Body Contact 

Recreation of 126 colonies per 100 mL (geometric mean of no 

less than five samples per 30 days) (State of Oklahoma, 2006). 

The largest measured Escherichia coli bacteria concentration 

(24,000 colonies per 100 mL) was measured in a water sample 

collected during runoff conditions at the Fourche Maline near 

Leflore, Okla., station (table 2).

Concentrations of Enterococcus sp. bacteria (fig. 9, 

table 2) were significantly larger (p≤0.05) in water samples 

collected during runoff conditions than in water samples 

collected during base-flow conditions at the three sampled 

stations. Concentrations of Enterococcus sp. bacteria in water 

samples collected at base-flow conditions were largest at 

the Poteau River at Loving, Okla., station. Concentrations 

of Enterococcus sp. bacteria concentrations in water 

samples collected during runoff conditions at the two 

Poteau River stations generally were larger than in water 

samples collected during runoff conditions at the Fourche 

Maline near Leflore, Okla., station. The smallest measured 

concentration of Enterococcus sp. bacteria (4 colonies per 

100 mL) was measured in a water sample collected during 

base-flow conditions at the Poteau River near Heavener, Okla., 

station (table 2). The largest concentration of Enterococcus 

sp. bacteria in water samples collected during base-flow 

conditions (>4,800 colonies per 100 mL) was measured at the 

Poteau River at Loving, Okla., station. Some water samples 

collected at baseflow conditions and most water samples 

collected at runoff conditions contained Enterococcus sp. 

bacteria concentrations exceeding the Oklahoma State Primary 

Body Contact Recreation of 33 colonies per 100 mL (which 

is based on a geographic mean of samples) (fig. 9; State of 

Oklahoma, 2006). The smallest Enterococcus sp. bacteria 

concentration measured during runoff conditions was less than 

the detection limit (<2 colonies per 100 mL) in a water sample 

collected at the Poteau River near Heavener, Okla., station 

(table 2). The largest Enterococcus sp. bacteria concentration 

measured in water samples collected during runoff conditions 

exceeded the maximum detection limit of 4,800 colonies per 

100 mL at each of these stations.

Seasonal Variation of Concentration

Total phosphorus, total nitrogen, and suspended 

sediment concentrations in these streams varied throughout 

the year, probably affected by a combination of factors such 

as precipitation amounts, land use in the upstream basins, 

ground cover in pastures, and streamflow. Total phosphorus 

and nitrogen concentrations can vary seasonally on the basis 

of timing of fertilizer and manure applications in addition 

to variable precipitation amounts (Storm and others, 2001). 

These factors increase the probability of larger phosphorus and 

nitrogen concentrations in streams during runoff conditions 

during the growing season (spring and summer); however, 

relatively large total phosphorus and nitrogen concentrations 

also were measured in these streams during base-flow 

conditions. Total phosphorus and nitrogen concentrations in 

streams downstream from urban areas may be larger during 

seasonal base flow when effluents from point sources such 

as WWT plants compose a substantial part of streamflow 

and dilution of those discharges is relatively small (U.S. 

Geological Survey, 1999). Suspended sediment concentration 

can vary seasonally, partly on the basis of the amount of 

ground cover in pastures during the nongrowing seasons 

(autumn and winter), when increased sediment runoff can 

occur (Wilson, 1972).

Estimated Annual Loads

Estimated annual loads of total phosphorus, total 

nitrogen, and suspended sediment for the three stations 

sampled for this report from 2011 to 2013 are described in 

this section. Total annual loads were divided into base-flow 

and runoff components. Linear regression models developed 
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin 17

laf14-0649_fig 08

C. Poteau River near Heavener, Oklahoma

A. Poteau River at Loving, Oklahoma B. Fourche Maline near Leflore, Oklahoma

10-1 10-1 100 101 102 103 104 105 100 101 102 103 104 105

10-1 100 101 102 103 104 105

EXPLANATION

Streamflow, in cubic feet per second Streamflow, in cubic feet per second

Streamflow, in cubic feet per second

Base-flow E. coli concentration

2011

2012

2013

2011

2012

2013

Runoff E. coli concentration

Oklahoma State Standard for Primary Contact—

126 colonies per 100 milliliters (State of 

Oklahoma, 2006)

0

5,000

10,000

15,000

20,000

25,000

0

5,000

10,000

15,000

20,000

25,000

Escherichia coli concentrations, in colonies per 100 milliliters

Figure 8. Total Escherichia coli bacteria concentrations in water-quality samples collected during base-flow and runoff conditions 

at the (A) Poteau River at Loving, Oklahoma; (B) Fourche Maline near Leflore, Okla.; and (C) Poteau River near Heavener, Okla., waterquality stations in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through September 2013.

Assessment of Concentrations in the Wister Lake Basin
18 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

laf14-0649_fig 09

C. Poteau River near Heavener, Oklahoma

A. Poteau River at Loving, Oklahoma B. Fourche Maline near Leflore, Oklahoma

10-1 10-1 100 101 102 103 104 105 100 101 102 103 104 105

10-1 100 101 102 103 104 105

EXPLANATION

Streamflow, in cubic feet per second Streamflow, in cubic feet per second

Streamflow, in cubic feet per second

5,000

5,000

0

2,000

1,000

3,000

4,000

0

2,000

1,000

3,000

4,000

Enterococcus sp. concentration, in colonies per 100 milliliters

Base-flow Enterococcus sp. concentration

2011

2012

2013

2011

2012

2013

Runoff Enterococcus sp. concentration

Oklahoma State Standard for Primary Contact—

33 colonies per 100 milliliters (State of 

Oklahoma, 2006)

Figure 9. Enterococcus sp. bacteria concentrations in water-quality samples collected during base-flow and runoff conditions at the 

(A) Poteau River at Loving, Oklahoma; (B) Fourche Maline near Leflore, Okla.; and (C) Poteau River near Heavener, Okla., water-quality 

stations in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through September 2013.
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin 19

by S-LOADEST for the estimation of loads of phosphorus, 

nitrogen, and sediment at each station for water years 2011–13 

are listed on table 3. In some cases, other S-LOADEST 

predefined regressions that used various combinations of 

streamflow, time, and seasonal coefficients had smaller 

residuals than the models used for this report; however, the 

“best-fit” model varied substantially among constituents and 

stations. Therefore, one general model was used to estimate 

loads of phosphorus and nitrogen (equation 3, shown earlier 

in this report) and sediment (equation 4, shown earlier in this 

report). The standard error of estimate (SEE) is the square 

root of residual variance. These log-transformed values, when 

multiplied by 100, can be interpreted as average percent error. 

The actual percent error for the Poteau River near Heavener, 

Okla., and the Fourche Maline near Leflore, Okla., stations 

may be slightly higher because of the greater uncertainty 

of the streamflow values. LOADEST can produce biased 

results, and the load bias can be identified by analyzing the 

model residuals. The standard error of prediction (SEP) is the 

standard deviation of the estimated value from the observed 

value and measures the amount of variance among the 

distribution of the estimates (Runkel and others, 2004).

Total Phosphorus

Total phosphorus loads during runoff conditions 

composed 86 to 96 percent of the total annual phosphorus 

load at the Poteau River stations (table 4). Total phosphorus 

loads during runoff conditions composed 87 to 98 percent of 

the total estimated annual phosphorus loads at the Fourche 

Maline near Leflore, Okla., station (table 4). Annual total 

phosphorus runoff loads were smaller in water year 2011 than 

in the subsequent 2 years at the Poteau River stations but were 

slightly larger than in the subsequent 2 years at the Fourche 

Maline near Leflore, Okla., station (table 4). 

Total Nitrogen

The runoff component of estimated total nitrogen loads 

at the Poteau River stations composed 82 to 91 percent of the 

total annual estimated total nitrogen load (table 5). Estimated 

runoff loads of total nitrogen at the Fourche Maline near 

Leflore, Okla., station composed 86 to 99 percent of the 

estimated total annual loads. The largest percentage of total 

nitrogen in runoff was estimated in 2011 at the three sampled 

stations during the 2011–13 study period (table 5). 

Table 3. Regression models used for estimating total phosphorus, total nitrogen, and suspended sediment loads at water-quality 

stations sampled in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 to September 2013.

[ln, natural logarithm; L, daily load in tons per day; Q, mean daily streamflow in cubic feet per second; sin, sine; cos, cosine; SS, seasonality parameter 

(2*pi*dectime). The standard error of the estimate is reported in natural logarithm units; therefore, this value, multiplied by 100, can be interpreted roughly as 

the average percent error]

Station name (number) Number of 

observations

Total phosphorus load 

regression model

Standard error 

of the estimate 

(ln of tons)

Poteau River at Loving, Okla. (07247015) 36 ln(L) = -3.24+1.26*lnQ-0.23*sin SS-0.16*cos SS 0.495

Poteau River near Heavener, Okla. (07247350) 37 ln(L) = -3.41+1.22*lnQ-0.310*sin SS-0.244*cos SS 0.511

Fourche Maline near Leflore, Okla. (07247650) 38 ln(L) = -4.96+1.18*lnQ-0.23*sin SS-0.18*cos SS 0.536

Station name (number) Number of 

observations

Total nitrogen load 

regression model

Standard error 

of the estimate 

(ln of tons)

Poteau River at Loving, Okla. (07247015) 36 ln(L) = -1.26+1.12*lnQ-0.21*sin SS+0.04*cos SS 0.358

Poteau River near Heavener, Okla. (07247350) 37 ln(L) = -1.26+1.09*lnQ-0.26*sin SS+0.12*cos SS 0.313

Fourche Maline near Leflore, Okla. (07247650) 34 ln(L) = -3.17+1.11*lnQ-0.30*sin SS+0.08*cos SS 0.327

Station name (number) Number of 

observations

Suspended sediment load 

regression model

Standard error 

of the estimate 

(ln of tons)

Poteau River at Loving, Okla. (07247015) 33 ln(L) = 1.95+1.41*lnQ+0.014*lnQ2 0.666

Poteau River near Heavener, Okla. (07247350) 33 ln(L) = 2.12+1.32*lnQ+0.23*lnQ2 0.876

Fourche Maline near Leflore, Okla. (07247650) 30 ln(L) = -0.03+1.21*lnQ+0.026*lnQ2 0.722

Assessment of Concentrations in the Wister Lake Basin
20 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

Table 4. Estimated annual total phosphorus loads and yields in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through 

September 2013.

[mi2, square mile; ton/yr, tons per year; ton∙yr-1∙mi-2, tons per year per square mile; SEP, standard error of prediction; P, phosphorus. Differences between baseflow loads plus runoff loads are due to rounding]

Station name 

(number)

Drainage 

area

(mi2

)

Water 

year

Estimated annual mean Portion of 

annual load 

delivered 

during 

runoff

(percent)

Annual 

load 

(ton/yr)

SEP 

(ton/yr 

as P)

Annual 

yield

(ton∙yr-1∙

mi-2 as P)

Baseflow 

load 

(ton/yr)

Base-flow 

yield

(ton∙yr-1∙

mi-2 as P)

Runoff 

load 

(ton/yr)

Runoff 

yield

(ton∙yr-1∙

mi-2 as P)

Poteau River at 

Loving, Okla. 

(07247015)

268 2011 51 0.03 0.190 2 0.008 49 0.183 96

2012 113 0.06 0.422 16 0.060 97 0.362 86

2013 92 0.05 0.343 13 0.048 79 0.295 86

3-year 

average

0.318 0.039 0.280

Poteau River near 

Heavener, Okla. 

(07247350)

515 2011 81 0.05 0.157 6 0.012 75 0.146 93

2012 164 0.09 0.318 17 0.033 147 0.285 90

2013 225 0.17 0.437 16 0.031 209 0.406 93

3-year 

average

0.304 0.025 0.279

Fourche Maline near 

Leflore, Okla. 

(07247650)

267 2011 56 0.03 0.208 1 0.002 55 0.206 98

2012 38 0.02 0.142 5 0.017 33 0.125 87

2013 53 0.02 0.198 5 0.017 48 0.181 91

3-year 

average

0.183 0.012 0.171

Suspended Sediment

Estimated suspended sediment loads at the Poteau River 

stations during runoff conditions composed 91 to 98 percent 

of the estimated total annual loads (table 6). At the Fourche 

Maline near Leflore, Okla., station, estimated suspended 

sediment loads during runoff conditions composed 91 to 

more than 99 percent of the total estimated annual suspended 

sediment loads (table 6). Annual runoff suspended sediment 

loads were largest in 2011–13 at the Poteau River near 

Heavener, Okla., station (table 6).

Estimated Seasonal Loads

Estimated seasonal total phosphorus, total nitrogen, and 

suspended sediment loads are described in this section. Those 

loads are divided into base-flow and runoff components 

(tables 7–9).

Total Phosphorus

Estimated seasonal loads of total phosphorus during 

base-flow conditions varied between the Poteau River stations 

and the Fourche Maline station in 2011–13 (table 7). At the 

Poteau River at Loving, Okla., station, the smallest estimated 

total phosphorus loads during base-flow conditions occurred 

in autumn (September through November). At the Poteau 

River at Heavener, Okla., station, the smallest estimated 

total phosphorus loads during base flow generally occurred 

during summer (June through August). At the Fourche 

Maline near LeFlore, Okla., station, the smallest estimated 

total phosphorus loads during base flow occurred in autumn 

(September through November). At the Poteau River stations, 

estimated total phosphorus loads at base-flow conditions 

typically were several times larger than at the Fourche Maline 

near Leflore, Okla., station (table 7). Estimated seasonal total 

phosphorus loads generally were largest in the winter during 

base-flow conditions.
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin 21

Table 5. Estimated annual total nitrogen loads and yields in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through 

September 2013.

[mi2, square mile; ton/yr, tons per year; ton∙yr-1∙mi-2, tons per year per square mile; SEP, standard error of prediction; P, phosphorus. Differences between baseflow loads plus runoff loads are due to rounding]

Station name 

(number)

Drainage 

area

(mi2

)

Water 

year

Estimated annual mean Portion of 

annual load 

delivered 

during 

runoff

(percent)

Annual 

load 

(ton/yr)

SEP 

(ton/yr 

as P)

Annual 

yield

(ton∙yr-1∙

mi-2 as P)

Base-flow 

load 

(ton/yr)

Base-flow 

yield

(ton∙yr-1∙

mi-2 as P)

Runoff 

load 

(ton/yr)

Runoff 

yield

(ton∙yr-1∙

mi-2 as P)

Poteau River at 

Loving, Okla. 

(07247015)

268 2011 217 0.1 0.81 20 0.075 197 0.74 91

2012 565 0.2 2.11 102 0.381 463 1.73 82

2013 436 0.1 1.63 45 0.168 391 1.46 90

3-year 

average

1.51 0.208 1.31

Poteau River near 

Heavener, Okla. 

(07247350)

515 2011 360 0.1 0.70 37 0.072 323 0.63 90

2012 1,023 0.3 1.99 140 0.272 883 1.71 86

2013 879 0.3 1.71 109 0.212 770 1.50 88

3-year 

average

1.46 0.185 1.28

Fourche Maline 

near Leflore, 

Okla. (07247650)

267 2011 296 0.1 1.11 5 0.018 292 1.09 99

2012 271 0.1 1.01 39 0.145 232 0.87 86

2013 306 0.1 1.15 32 0.120 274 1.02 90

3-year 

average

1.09 0.094 1.00

Estimated seasonal total phosphorus loads during 

runoff conditions typically were largest in spring (March 

through May) and smallest in autumn (September through 

November) at these three stations. Annual estimated total 

phosphorus seasonal loads typically were several times larger 

at the Poteau River stations than at the Fourche Maline near 

Leflore, Okla., station (table 7).

Total Nitrogen 

Estimated seasonal loads of total nitrogen generally 

were largest at the Poteau River near Heavener, Okla., station 

for all seasons (table 8). Estimated seasonal total nitrogen 

loads during base-flow conditions generally were smallest 

during the autumn for all stations (table 8). The smallest total 

nitrogen loads during base-flow conditions were estimated 

at the Fourche Maline near Leflore, Okla., station in autumn. 

The majority of the total nitrogen was delivered to Wister 

Lake during runoff conditions in winter. At the Poteau River 

stations, estimated total nitrogen seasonal loads at base-flow 

conditions were several times larger than at the Fourche 

Maline near Leflore, Okla., station (table 8). Estimated total 

nitrogen seasonal loads during runoff conditions generally 

were largest in winter and spring for the Poteau River Stations 

and were largest during the spring at the Fourche Maline near 

Leflore, Okla., station (table 8). 

Suspended Sediment

Estimated seasonal suspended sediment loads during 

base-flow conditions generally were smallest in the summer 

at the Poteau River stations and smallest in the autumn at the 

Fourche Maline near Leflore, Okla., station (table 9). The 

estimated seasonal suspended sediment loads at base-flow 

conditions generally were smallest at the Poteau River at 

Loving, Okla., station during summer. Estimated seasonal 

base-flow suspended sediment loads at the Poteau River 

stations typically were several times larger than at the Fourche 

Maline near Leflore, Okla., station (table 9).

Estimated seasonal suspended sediment loads during 

runoff conditions typically were largest in the spring and 

smallest during the autumn (table 9). Seasonal runoff 

suspended sediment loads at the Poteau River stations 

generally were larger than those estimated at the Fourche 

Maline near Leflore, Okla., station (table 9).

Assessment of Concentrations in the Wister Lake Basin
22 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

Comparison of Estimated Annual Yields

Among Stations

Estimated annual yields for total phosphorus, total 

nitrogen, and suspended sediment for the three sampled 

stations in the Wister Lake Basin for the period 2011–13 are 

described in this section. The annual yields also are divided 

into base-flow and runoff components. 

Total Phosphorus

Estimated annual total phosphorus yield slightly 

decreased in the downstream direction in 2011 and 2012 and 

increased slightly in the downstream direction (Loving to 

Heavener, Okla.) in 2013 at the Poteau River stations (table 

4). Annual total phosphorus yield at the Fourche Maline 

near Leflore, Okla., station decreased from 2011 to 2012 

and increased from 2012 to 2013 (table 4). Annual yields 

of total phosphorus ranged from 0.142 to 0.437 tons per 

year per square mile (ton∙yr-1∙mi-2) at these stations, with 

the largest mean annual yield estimated at the Poteau River 

near Heavener, Okla., station in 2013 and the smallest yield 

estimated at the Fourche Maline near Leflore, Okla., station in 

2012 (table 4). 

Estimated mean annual total phosphorus yields during 

base-flow conditions were largest at the Poteau River at 

Loving, Okla., station (table 4). The smallest mean annual 

yield during base-flow conditions was at the Fourche Maline 

near Leflore, Okla., station (table 4). Annual estimated total 

phosphorus yields during base-flow conditions at these 

stations ranged from 0.002 to 0.060 ton∙yr-1∙mi-2 (table 4). 

Mean estimated yields during runoff conditions were 

largest at the Poteau River stations (table 4). Annual estimated 

total phosphorus yields during runoff conditions at the three 

sampled stations ranged from 0.125 to 0.406 ton∙yr-1∙mi-2

(table 4). The largest estimated total phosphorus yield during 

runoff conditions was at the Poteau River near Heavener, 

Okla., station in 2013, whereas the smallest estimated total 

phosphorus yield during runoff conditions was at the Fourche 

Maline near Leflore, Okla., station in 2012 (table 4).

Table 6. Estimated annual suspended sediment loads and yields in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 

through September 2013.

[mi2, square mile; ton/yr, tons per year; ton∙yr-1∙mi-2, tons per year per square mile; SEP, standard error of prediction. Differences between base-flow loads and 

runoff loads are due to rounding; 99+, less than 100 percent]

Station name (number)

Drainage 

area

(mi2

)

Water 

year

Estimated annual mean Portion 

of annual 

load 

delivered

during 

runoff

(percent)

Annual 

load 

(ton/yr)

SEP

(ton/yr)

Annual 

yield

(ton∙yr-1∙

mi-2)

Baseflow 

load

(ton/yr)

Baseflow 

yield

(ton∙yr-1∙

mi-2)

Runoff 

load 

(ton/yr)

Runoff 

yield

(ton∙yr-1∙

mi-2)

Poteau River at Loving, Okla. 

(07247015)

268 2011 23,787 22 89 450 2 23,337 87 98

2012 52,351 46 195 4,822 18 47,530 177 91

2013 41,496 31 155 1,719 6 39,777 148 96

3-year 

average

146 9 138

Poteau River near Heavener, 

Okla. (07247350)

515 2011 56,588 73 110 1,377 3 55,211 107 98

2012 121,911 132 237 7,274 14 114,637 223 94

2013 191,589 361 372 6,261 12 185,327 360 97

3-year 

average

240 10 230

Fourche Maline near Leflore, 

Okla. (07247650)

267 2011 54,321 52 203 252 1 54,069 202 99+

2012 35,926 30 135 2,415 9 33,511 126 93

2013 43,229 32 162 3,692 14 39,537 148 91

3-year 

average

167 8 159
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin 23

Total Nitrogen

Estimated mean annual total nitrogen yields were largest 

at the Poteau River stations (table 5). Total nitrogen yields 

ranged from 0.70 to 2.11 ton∙yr-1∙mi-2, with the largest annual 

total nitrogen yield being estimated at the Poteau River at 

Loving, Okla., station in 2012 and the smallest total nitrogen 

yield being estimated at the Poteau River near Heavener, 

Okla., station in 2011 (table 5). 

Estimated mean annual total nitrogen yields at base-flow 

conditions were largest at the Poteau River at Loving, Okla., 

station (table 5). Estimated mean annual total nitrogen yields 

at base-flow conditions were smallest at the Fourche Maline 

near Leflore, Okla., station (table 5). Estimated total nitrogen 

yields at base-flow conditions at these three stations ranged 

from 0.018 to 0.381 ton∙yr-1∙mi-2. The largest total nitrogen 

yield during base-flow conditions was estimated at the Poteau 

River at Loving, Okla., station in 2012, and the smallest yield 

was estimated at the Fourche Maline station in 2011 during 

the 3-year study period. 

Estimated mean annual total nitrogen yields during 

runoff conditions were largest at the Poteau River at Loving, 

Okla., station (table 5). At the Fourche Maline near Leflore, 

Okla., station, estimated total nitrogen yields during runoff 

conditions typically were the smallest of the three sampled 

stations (table 5). Estimated total nitrogen yields during 

runoff conditions at these stations ranged from 0.63 to 

1.73 ton∙yr-1∙mi-2. The largest total nitrogen yield during 

runoff conditions was estimated at the Poteau River at 

Loving, Okla., station in 2012, and the smallest total nitrogen 

yield during runoff conditions was estimated at the Poteau 

River near Heavener, Okla., station in 2011 (table 5).

Table 7. Estimates of seasonal total phosphorus loads during base-flow and runoff conditions in the Wister Lake Basin, Oklahoma and 

Arkansas, October 2010 through September 2013.

[Values are loads in tons per season as phosphorus; spring is March through May, summer is June through August, autumn is September through November, and 

winter is December through February]

Flow type Station name (number)

Estimated seasonal total phosphorus loads

Water 

year Spring Summer Autumn Winter

Base flow

Poteau River at Loving, Okla. 

(07247015)

2011 1.06 0.30 0.79 0.15

2012 2.50 0.01 1.76 11.50

2013 3.95 7.76 0.03 1.55

Runoff

2011 46.58 1.07 0.06 0.85

2012 19.85 0.13 44.89 32.17

2013 29.35 41.19 1.35 7.75

Base flow

Poteau River near Heavener, 

Okla. (07247350)

2011 1.92 0.81 0.99 0.77

2012 4.45 0.01 2.74 9.90

2013 9.51 2.85 0.06 3.18

Runoff

2011 70.55 1.22 0.13 2.74

2012 31.73 0.18 61.63 53.59

2013 110.60 85.64 1.86 10.97

Base flow

Fourche Maline near Leflore, 

Okla. (07247650)

2011 0.24 0.36 0.01 0.03

2012 2.18 0.04 0.24 2.06

2013 3.62 0.49 0.03 0.45

Runoff

2011 54.08 0.08 0.30 54.90

2012 20.03 0.98 0.96 33.45

2013 30.70 14.68 0.14 48.37

Assessment of Concentrations in the Wister Lake Basin
24 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

Table 8. Estimates of seasonal total nitrogen loads during base-flow and runoff conditions in the Wister Lake Basin, Oklahoma and 

Arkansas, October 2010 through September 2013.

[Values are loads in tons per season as nitrogen; spring is March through May, summer is June through August, autumn is September through November, and 

winter is December through February]

Flow type Station name (number)

Estimated seasonal total nitrogen loads

Water 

year Spring Summer Autumn Winter

Base flow

Poteau River at Loving, Okla. 

(07247015)

2011 7.2 16.2 6.6 3.8

2012 15.0 0.1 11.0 67.0

2013 23.0 6.0 0.3 11.0

Runoff

2011 184.6 5.0 0.5 6.0

2012 85.0 1.0 179.0 153.0

2013 163.0 144.0 7.0 42.0

Base flow

Poteau River near Heavener, 

Okla. (7247350)

2011 15.0 5.0 9.0 9.0

2012 32.0 0.1 22.0 86.0

2013 62.0 15.0 1.0 30.0

Runoff

2011 290.0 6.0 1.0 323.0

2012 174.0 1.0 345.0 882.0

2013 390.0 286.0 12.0 771.0

Base flow

Fourche Maline near Leflore, 

Okla. (07247650)

2011 1.6 2.5 0.2 0.4

2012 15.9 0.4 2.7 19.7

2013 23.8 3.0 0.3 4.8

Runoff

2011 283.2 0.6 3.2 4.7

2012 122.9 5.8 9.2 94.5

2013 174.7 73.5 1.4 24.0
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin 25

Table 9. Estimates of seasonal suspended sediment loads during base-flow and runoff conditions in the Wister Lake Basin, Oklahoma 

and Arkansas, October 2010 through September 2013.

[Values are loads in tons per season as sediment; spring is March through May, summer is June through August, autumn is September through November, and 

winter is December through February]

Flow 

type Station name (number)

Estimated seasonal suspended sediment load

Water 

year Spring Summer Autumn Winter

Base flow

Poteau River at Loving, Okla.

(07247015)

2011 246 50 122 32

2012 778 1 464 3,579

2013 1,090 173 4 446

Runoff

2011 22,846 242 10 238

2012 10,038 18 22,047 15,411

2013 13,560 16,055 297 3,134

Base flow

Poteau River near Heavener, 

Okla. (07247350)

2011 665 198 207 305

2012 1,988 3 1,037 4,244

2013 4,083 674 13 1,471

Runoff

2011 53,576 342 36 1,251

2012 26,986 34 46,495 41,097

2013 114,044 63,756 529 7,026

Base flow

Fourche Maline near Leflore, 

Okla. (07247650)

2011 107 125 4 15

2012 1,171 14 89 1,139

2013 3,075 379 9 221

Runoff

2011 53,728 23 108 208

2012 21,641 433 501 10,937

2013 25,821 11,664 48 2,005

Assessment of Concentrations in the Wister Lake Basin
26 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

Suspended Sediment

Estimated mean annual sediment yields were largest at 

the Poteau River near Heavener, Okla., station (table 6). The 

estimated mean annual suspended sediment yield was smallest 

at the Poteau River at Loving, Okla., station. Suspended 

sediment yields at the three stations during this period ranged 

from 89 to 372 ton∙yr-1∙mi-2, with the largest yield being 

estimated at the Poteau River near Heavener, Okla., station in 

2013 and the smallest yield being estimated at Poteau River at 

Loving, Okla., station in 2011 (table 6).

The estimated mean annual suspended sediment yield 

at base-flow conditions was largest at the Poteau River 

near Heavener, Okla., station (table 6). Estimated mean 

annual suspended sediment yields at base-flow conditions 

were smallest at the Fourche Maline near Leflore, Okla., 

station. Suspended sediment yields at base-flow conditions 

ranged from 1 to 18 ton∙yr-1∙mi-2 (table 6). The largest annual 

suspended sediment yield at base-flow conditions was 

estimated at the Poteau River at Loving, Okla., station in 2012, 

whereas the smallest suspended sediment yield at base-flow 

conditions was estimated at the Fourche Maline near Leflore, 

Okla., station in 2011 (table 6). 

The estimated mean annual suspended sediment yield 

at runoff conditions was largest at the Poteau River near 

Heavener, Okla., station (table 6). Estimated annual suspended 

sediment yields during runoff conditions ranged from 87 to 

360 ton∙yr-1∙mi-2 (table 6). The largest suspended sediment 

yield during runoff conditions was estimated at the Poteau 

River near Heavener, Okla., station in 2013, and the smallest 

suspended sediment yield at runoff conditions was estimated 

at the Poteau River at Loving, Okla., station in 2011 (table 6).

Estimated Annual Flow-Weighted Mean 

Concentrations of Total Phosphorus and Total 

Nitrogen

Flow-weighted mean (FWM) concentrations, determined 

by dividing total annual constituent loads by mean annual 

streamflow, are useful for investigating trends in constituent 

concentrations by reducing the effects of wet and dry years on 

constituent concentrations. The following sections describe 

annual FWM concentrations of total phosphorus and total 

nitrogen at three sampled stations in the Wister Lake Basin 

from October 2011 through September 2013.

Total Phosphorus

Estimated annual FWM concentrations of total 

phosphorus were substantially larger than the Oklahoma 

State Standard for Scenic Rivers of 0.037 mg/L at the three 

sampled stations (State of Oklahoma, 2006; table 10). This 

standard is useful as a point of reference because phosphorus 

concentrations exceeding that standard may be associated 

with greater eutrophication in rivers and downstream lakes 

receiving inflows from rivers. The FWM concentration of total 

phosphorus was much more stable over the 3-year period at 

the Poteau River at Loving, Okla., station than at the other 

two stations (table 10). The FWM concentration of total 

Table 10. Estimated annual total phosphorus loads, mean annual streamflows, and flow-weighted mean total phosphorus 

concentrations at water-quality stations in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through September 2013.

[ton/yr, tons per year; ft3/s, cubic feet per second; mg/L, milligrams per liter]

Station name (number) Water 

year

Estimated mean 

annual total 

phosphorus load

(ton/yr as P)

Mean annual 

streamflow 

(ft3

/s)

Estimated flow-weighted 

mean total phosphorus 

concentration 

(mg/L as P)

Poteau River at Loving, Okla. 

(07247015)

2011 51 192.6 0.270

2012 112 405.8 0.281

2013 100 379.9 0.268

Poteau River near Heavener, 

Okla. (07247350)

2011 79 415.0 0.194

2012 164 846.7 0.197

2013 225 911.0 0.251

Fourche Maline near Leflore, 

Okla. (07247650)

2011 56 265.9 0.212

2012 38 232.9 0.165

2013 53 281.7 0.191
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin 27

Table 11. Estimated annual total nitrogen loads, mean annual streamflows, and flow-weighted mean total nitrogen concentrations at 

water-quality stations in the Wister Lake Basin, Oklahoma and Arkansas, October 2010 through September 2013.

[ton/yr, tons per year; ft3/s, cubic feet per second; mg/L, milligrams per liter]

Station name (number) Water 

year

Estimated mean annual 

total nitrogen load

(ton/yr as N)

Mean annual 

streamflow 

(ft3

/s)

Estimated flowweighted mean total 

nitrogen concentration 

(mg/L as N)

Poteau River at Loving, Okla. 

(07247015)

2011 214 192.6 1.129

2012 564 405.8 1.408

2013 435 379.9 1.166

Poteau River near Heavener, 

Okla. (07247350)

2011 360 415.0 0.882

2012 1,023 846.7 1.225

2013 879 911.0 0.981

Fourche Maline near Leflore, 

Okla. (07247650)

2011 296 265.9 1.133

2012 271 232.9 1.179

2013 306 281.7 1.103

phosphorus typically was lower at the Fourche Maline near 

Leflore, Okla., station than at the Poteau River stations.

Total Nitrogen

Estimated FWM concentrations of total nitrogen at 

these three stations were substantially larger than the median 

flow-weighted concentration (0.26 mg/L) described for mostly 

undeveloped basins of the United States by Clark and others 

(2000) (table 11). Such nitrogen concentrations, along with 

relatively large phosphorus concentrations in these samples, 

are likely to be contributing to the eutrophication in Wister 

Lake. Flow-weighted mean concentrations of total nitrogen 

did not vary spatially in a consistent manner. 

Estimated Annual Total Phosphorus, Total 

Nitrogen, and Suspended Sediment Loads 

Discharged into Wister Lake

Most of the annual total phosphorus, total nitrogen, and 

suspended sediment loads discharged to Wister Lake can 

be estimated by adding the loads of the Poteau River near 

Heavener, Okla., station and the Fourche Maline near Leflore, 

Okla., station. The estimated loads of total phosphorus, total 

nitrogen, and suspended sediment at those stations do not 

represent the entire drainage area for Wister Lake but account 

for about 84 percent of the drainage basin of the lake. 

The Poteau River and the Fourche Maline contributed 

estimated annual total phosphorus loads of 137 to 278 tons/yr, 

with 89 to 95 percent of those annual total phosphorus loads 

being transported to Wister Lake during runoff conditions 

(table 12). The Poteau River transported several times more 

total phosphorus to the lake during base-flow and runoff 

conditions than the Fourche Maline (table 12). The estimated 

seasonal total phosphorus loads into Wister Lake typically 

were largest during runoff conditions in the spring at the 

Poteau River stations and during runoff conditions in the 

winter at the Fourche Maline near Leflore, Okla., station (table 

7).

The Poteau River and the Fourche Maline contributed 

estimated annual total nitrogen loads of 657 to 1,294 tons/

yr, with 86 to 94 percent of the estimated annual total 

nitrogen loads being transported to Wister Lake during runoff 

conditions (table 13). The Poteau River typically transported 

several times more nitrogen during base-flow and runoff 

conditions to the lake than the Fourche Maline (table 13). The 

estimated seasonal total nitrogen loads transported into Wister 

Lake typically were largest during runoff conditions in the 

spring at these sampled stations (table 8).

The Poteau River and the Fourche Maline contributed 

annual estimated suspended sediment loads of 110,919 to 

234,637 tons/yr, with 94 to 99 percent of the annual suspended 

sediment loads being transported to Wister Lake during runoff 

conditions (table 14). The Poteau River typically transported 

several times more sediment during base-flow and runoff 

conditions to the lake than the Fourche Maline (table 14). The 

estimated seasonal suspended sediment loads into Wister Lake 

generally were largest during runoff conditions in the spring 

for all stations (table 9).

Assessment of Concentrations in the Wister Lake Basin
28 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

Table 12. Estimated annual total phosphorus loads discharged to Wister Lake, Oklahoma and Arkansas, October 2010 through 

September 2013.

[%, percent; ton/yr, tons per year]

Flow type

(water year)

Discharged to Wister Lake 

from 84% of its drainage area

Poteau River near 

Heavener, Okla.

Fourche Maline near

Annual phosphorus load Leflore, Okla. 1 Component of mean annual 

phosphorus load 

(ton/yr) ton/yr as P %

2011

Base flow2 7 5 6 1

Runoff3 130 95 75 55

Total4 137 100 81 56

2012

Base flow2 22 11 17 5

Runoff3 180 89 147 33

Total4 202 100 164 38

2013

Base flow2 21 8 16 5

Runoff3 257 92 209 48

Total4 278 100 225 53

Average of 3 years, 2011–13

Base flow2 17 13 4

Runoff3 189 144 45

Total4 206 157 49

1

Loads to Wister Lake are calculated by adding loads from Poteau River near Heavener, Okla., to loads from Fourche Maline near Leflore, Okla. (table 4). 

These two stations account for 84 percent of drainage that flows into Wister Lake.

2

Means of the base-flow loads are calculated from base-flow day data only by using S-LOADEST.

3

Means of the runoff loads are calculated from runoff day data only by using S-LOADEST. 

4

Differences between total loads and the sum of base flow plus runoff are due to rounding.
Assessment of Concentrations, Loads, and Yields of Total Phosphorus, Total Nitrogen, and Suspended Sediment and Bacteria Concentrations in the Wister Lake Basin 29

Table 13. Estimated annual total nitrogen loads discharged to Wister Lake, Oklahoma and Arkansas, October 2010 through September 

2013.

[%, percent; ton/yr, tons per year]

Flow type

(water year)

Discharged to Wister Lake from 

84% of its drainage area Poteau River near Heavener, Okla.

Fourche Maline near 

Annual nitrogen load Leflore, Okla. 1 Component of mean 

annual nitrogen load

(ton/yr) ton/yr as N %

2011

Base flow2 42 6 37 5

Runoff3 615 94 323 292

Total4 657 100 360 297

2012

Base flow2 179 14 140 39

Runoff3 1,115 86 883 232

Total4 1,294 100 1,023 271

2013

Base flow2 141 12 109 32

Runoff3 1,044 88 770 274

Total4 1,185 100 879 306

Average of 3 years, 2011–13

Base flow2 120 95 25

Runoff3 925 659 266

Total4 1,045 754 291

1

Loads to Wister Lake are calculated by adding loads from Poteau River near Heavener, Okla., to loads from Fourche Maline near Leflore, Okla. (table 5). 

These two stations account for 84 percent of drainage that flows into Wister Lake.

2

Means of the base-flow loads are calculated from base-flow day data only by using S-LOADEST.

3

Means of the runoff loads are calculated from runoff day data only by using S-LOADEST. 

4

Differences between total loads and the sum of base flow plus runoff are due to rounding.

Assessment of Concentrations in the Wister Lake Basin
30 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

Table 14. Estimated annual total suspended sediment loads discharged to Wister Lake, Oklahoma and Arkansas, October 2010 through 

September 2013.

[%, percent; ton/yr, tons per year]

Flow type

(water year)

Discharged to Wister Lake from 

84% of its drainage area Poteau River near Heavener, Okla.

Fourche Maline near 

Leflore, Okla. Annual sediment load1 Component of mean 

annual sediment load 

(ton/yr) ton/yr %

2011

Base flow2 1,629 1 1,377 252 

Runoff3 109,290 99 55,221 54,069 

Total4 110,919 100 56,598 54,321 

2012

Base flow2 9,689 6 7,274 2,415

Runoff3 148,148 94 114,637 33,511 

Total4 157,837 100 121,911 35,926 

2013

Base flow2 9,953 4 6,261 3,692 

Runoff3 224,684 96 185,327 39,357 

Total4 234,637 100 191,588 43,049

Average of 3 years, 2011–13

Base flow2 7,090 4,971 1,389 

Runoff3 160,707 118,395 42,312

Total4 167,797 123,366 43,701

1

Loads to Wister Lake are calculated by adding loads from Poteau River near Heavener, Okla., to loads from Fourche Maline near Leflore, Okla. (table 6). 

These two stations account for 84 percent of drainage that flows into Wister Lake.

2

Means of the base-flow loads are calculated from base-flow day data only by using S-LOADEST.

3

Means of the runoff loads are calculated from runoff day data only by using S-LOADEST. 

4

Differences between total loads and the sum of base flow plus runoff are due to rounding.
Summary 31

Summary

The Poteau Valley Improvement Authority uses Wister 

Lake in southeastern Oklahoma as a sole source of public 

water supply. Total phosphorus, total nitrogen, and suspended 

sediments from agricultural runoff and discharges from 

wastewater treatment plants and other sources have caused 

impairment of water quality in the lake. Lake-water quality 

has degraded, causing water-treatment cost, chemical usage, 

and sludge production to increase for the Poteau Valley 

Improvement Authority. 

The U.S. Geological Survey, in cooperation with 

the Poteau Valley Improvement Authority, investigated 

and summarized concentrations of total phosphorus, total 

nitrogen, suspended sediment, and bacteria (Escherichia coli 

and Enterococcus sp.) in surface water flowing to Wister 

Lake. Estimates of total phosphorus, total nitrogen, and 

suspended sediment loads and yields, and flow-weighted 

mean concentrations of total phosphorus and total nitrogen 

were made for the Wister Lake Basin for a 3-year period, 

October 2010 through September 2013. Samples collected 

at fixed time increments during base-flow conditions at 

the Poteau River at Loving, Okla.; the Poteau River near 

Heavener, Okla.; and the Fourche Maline near Leflore, Okla., 

water-quality stations were supplemented with samples 

collected during runoff conditions to determine water quality 

over the range of streamflows in the basin. These data also 

were collected to estimate annual constituent loads by using 

regression models. 

Total phosphorus, total nitrogen, and suspended 

sediment concentrations were significantly larger in water 

samples collected during runoff conditions than in samples 

collected during base-flow conditions at the Poteau River 

stations. Bacteria (Escherichia coli and Enterococcus sp.) 

concentrations also were significantly larger in water samples 

collected during runoff conditions than in water samples 

collected during base-flow conditions from 2011 to 2013 at 

the three sampled stations. 

Concentrations of total phosphorus, total nitrogen, 

suspended sediment, and bacteria (Escherichia coli and 

Enterococcus sp.) in water samples collected during baseflow conditions generally were larger at the Fourche Maline 

station than at the Poteau River stations. Total phosphorus, 

total nitrogen, and suspended sediment concentrations in 

water samples collected during runoff conditions were larger 

at the Poteau River stations than at the Fourche Maline near 

Leflore, Okla., station. 

Estimated annual total phosphorus and total nitrogen 

loads generally were larger at the Poteau River stations 

than at the Fourche Maline near Leflore, Okla., station. 

Estimated annual suspended sediment loads were largest at 

the Poteau River near Heavener, Okla., station and generally 

were smallest at the Poteau River at Loving, Okla., station. 

Estimated annual total phosphorus, total nitrogen, and 

suspended sediment loads at the Poteau River stations at 

base-flow conditions generally were larger than at the Fourche 

Maline near Leflore, Okla., station. The estimated annual loads 

of total phosphorus, total nitrogen, and suspended sediment in 

the Poteau River stations during runoff conditions ranged from 

82 to 98 percent of the total annual loads of those constituents. 

The estimated annual loads of total phosphorus, total nitrogen, 

and suspended sediment in the Fourche Maline during runoff 

conditions ranged from 86 to nearly 100 percent of the total 

annual loads.

Estimated seasonal total phosphorus loads generally were 

smallest during base-flow and runoff conditions in autumn. 

Estimated seasonal total phosphorus loads during base-flow 

conditions generally were largest in winter and during runoff 

conditions generally were largest in the spring. Estimated 

seasonal total nitrogen loads generally were smallest in 

autumn during base-flow conditions and largest in winter 

during runoff conditions. Estimated seasonal suspended 

sediment loads generally were smallest during base-flow 

conditions in the summer and during runoff conditions in the 

autumn. The largest estimated seasonal suspended sediment 

loads typically were in the spring during runoff conditions.

Estimated mean annual total phosphorus yields were 

largest at the Poteau River at Loving, Okla., station. The 

estimated mean total phosphorus yields were largest during 

base-flow at the Poteau River at Loving, Okla., station. 

Estimated mean annual total nitrogen yields were largest at 

the Poteau River stations. The estimated mean total nitrogen 

yields during base-flow and runoff conditions were largest at 

the Poteau River at Loving, Okla., station. Estimated mean 

annual, base-flow, and runoff yields of suspended sediment 

were largest at the Poteau River near Heavener, Okla., station. 

Flow-weighted mean total phosphorus concentrations 

at all three stations from 2011 to 2013 were several times 

larger than Oklahoma State Standard for Scenic Rivers 

(0.037 milligrams per liter), with the largest flow-weighted 

phosphorus concentrations typically being measured at 

the Poteau River at Loving, Okla., station. Flow-weighted 

mean concentrations indicated that total phosphorus inputs 

from the Poteau River Basin in the Wister Lake Basin were 

larger than from the Fourche Maline Basin. Flow-weighted 

mean concentrations of total nitrogen did not vary spatially 

in a consistent manner. Flow-weighted mean total nitrogen 

concentrations did not vary substantially between the Poteau 

River stations and the Fourche Maline near Leflore, Okla., 

station. 

The Poteau River and the Fourche Maline contributed 

estimated annual total phosphorus loads of 137 to 278 tons per 

year to Wister Lake. Between 89 and 95 percent of the annual 

total phosphorus loads were transported to Wister Lake during 

runoff conditions. The Poteau River typically transported 

several times larger total phosphorus loads during base-flow 

conditions and runoff conditions than the Fourche Maline. The 

Poteau River and the Fourche Maline contributed estimated 
32 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

annual total nitrogen loads of 657 to 1,294 tons per year, 

with 86 to 94 percent of the annual total nitrogen loads being 

transported to Wister Lake during runoff conditions. Several 

times larger total nitrogen loads typically were delivered to 

the lake during base-flow and runoff conditions from the 

Poteau River than the Fourche Maline. The Poteau River 

and the Fourche Maline contributed estimated annual total 

suspended sediment loads of 110,919 to 234,637 tons per year, 

with 94 to 99 percent of the annual suspended sediment loads 

being transported to Wister Lake during runoff conditions. 

Several times more suspended sediment loads typically were 

transported to the lake by the Poteau River than the Fourche 

Maline. Most of the total phosphorus, total nitrogen, and 

suspended sediment were discharged to Wister Lake during 

runoff conditions in the spring.

Selected References

Andrews, W.J., Becker, M.F., Smith, S.J., and Tortorelli, R.L., 

2009, Summary of surface-water quality data from the 

Illinois River Basin in North Oklahoma, 1970–2007: U.S. 

Geological Survey Scientific Investigations Report 2009–

5182, 39 p. (Revised April 2010)

Busteed, P.R., Storm, D.E., White, M.J., and Stoodley, S.H., 

2009, Using SWAT to target critical source suspended 

sediment and phoshporus areas in the Wister Lake Basin, 

USA: American Journal of Environmental Sciences, v. 5, 

no. 2, p. 156–163.

Clark, G.M., Mueller, D.K., and Mast, M.A., 2000, Nutrient 

concentrations and yields in undeveloped stream basins of 

the United States: Journal of the American Water Resources 

Association, v. 36, no. 4, p. 849–860.

Cohn, T.A., DeLong, L.L., Gilroy, E.J., Hirsch, R.M., and 

Wells, D.K., 1989, Estimating constituent loads: Water 

Resources Research, v. 25, no. 5, p. 937–942.

Crawford, C.G., 1991, Estimation of suspended-suspended 

sediment rating curves and suspended-suspended sediment 

loads: Journal of Hydrology, v. 129, no. 1, p. 331–348.

Dempster, A.P., Laird, N.M., and Rubin, D.B., 1977, 

Maximum likelihood from incomplete data via the EM 

algorithm: Journal of the Royal Statistical Society, series B, 

v. 39, no. 1, p. 1–38.

Edwards, T.K., and Glysson, G.D., 1999, Field methods 

for measurements of fluvial suspended sediment: U.S. 

Geological Survey Techniques of Water-Resources 

Investigations, book 3, chap C2, 89 p.

Esralew, R.A., Andrews, W.J., Allen, M.L.O., and Becker, C.J., 

2011, Comparison of load estimation techniques and trend 

analysis for nitrogen, phosphorus, and suspended sediment 

in the Eucha-Spavinaw Basin, northwestern Arkansas and 

northeastern Oklahoma, 2002–10: U.S. Geological Survey 

Scientific Investigations Report 2011–5127, 58 p.

Harwell, G.R., and Mobley, C.A., 2009, Occurrence and 

distribution of fecal indicator bacteria, and physical and 

chemical indicators of water quality in streams receiving 

discharge from Dallas/Fort Worth International Airport 

Vicinity, north-central Texas, 2008: U.S. Geological Survey 

Scientific Investigations Report 2009–5103, 44 p.

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

water resources: Amsterdam, Netherlands, Elsevier, 522 p.

Hession, W.C., Storm, D.E., Haan, C.T., Burks, S.L., and 

Matlock, M.D., 1996, A watershed-level ecological risk 

assessment methodology: Journal of the American Water 

Resources Association, v. 32, p. 1039–1054.

IDEXX Laboratories, 2009, Water microbiology/Colilert/

Document library/Colilert procedure: IDEXX Laboratories, 

accessed December 15, 2013, at http://www.idexx.com/

water/refs/0612999_c.pdf.

Insightful Corporation, 2005, S-Plus 7.0 for Windows 

professional developer release edition with release 3.0 

of the U.S. Geological Survey S-Plus Library: Insightful 

Corporation, Seattle, Washington.

Institute of Hydrology, 1980a, Low flow studies: Wallington, 

Oxon, United Kingdom, Institute of Hydrology Report, no. 

1, 21 p.

Institute of Hydrology, 1980b, Low flow studies: Wallington, 

Oxon, United Kingdom, Institute of Hydrology Report, no. 

3, p. 12–19.

Langbein, W.B., and Iseri, K.T., 1960, General introductions 

and hydrologic definitions—Manual of Hydrology—Part I, 

general surface-water techniques: U.S. Geological Survey 

Water-Supply Paper 1541–A, 29 p.
Selected References 33

Mott, D.N., and Steele, K.F., 1991, Effects of pasture runoff 

on water chemistry, Buffalo National River, USA, in Peters, 

N.E., and Walling, D.E., eds., Suspended sediment and 

stream water quality in a changing environment—Trends 

and explanation, 20th, Vienna, Austria, 1991, Proceedings: 

Vienna, Austria, 20th General Assembly of the International 

Union of Geodesy and Geophysics, p. 229–238.

Multi-Resolution Land Characteristics Consortium, 2013, 

National land cover database 2006: Multi-Resolution Land 

Characteristics Consortium, accessed December 15, 2013, 

at http://www.mrlc.gov/nlcd2006.php.

Oklahoma Conservation Commission, 2001a, Watershed 

restoration action strategy (WRAS) for the Poteau 

River/Wister Lake watershed: Oklahoma Conservation 

Commission, accessed December 15, 2013, at http://www.

ok.gov/triton/search.php?cref=http%3A%2F%2Fwww.

ok.gov%2Ftriton%2Fcse_search_xml.php?site=http://www.

ok.gov/conservation/*&sitesearch=http://www.ok.gov/

conservation/&q=lake%20wister%20basin&as_epq=&as_

oq=&as_eq=&as_occt=any&sort=&num=10&cof=FORID

%3A9%3BNB%3A1#947.

Oklahoma Conservation Commision, 2001b, Poteau 

River comprehensive watershed management program: 

Oklahoma Conservation Commission, accessed 

December 15, 2013, at http://www.ok.gov/triton/search.

php?cref=http%3A%2F%2Fwww.ok.gov%2Ftriton%2Fcse_

search_xml.php?site=http://www.ok.gov/conservation/*&

sitesearch=http://www.ok.gov/conservation/&q=lake%20

wister%20basin&as_epq=&as_oq=&as_eq=&as_occt=any

&sort=&num=10&cof=FORID%3A9%3BNB%3A1#947.

Oklahoma Department of Environmental Quality, 2008, 

Water quality in Oklahoma, 2008, integrated report: 

Oklahoma Department of Environmental Quality, accessed 

November 20, 2013, at http://www.deq.state.ok.us/

WQDnew/305b_303d/2008_integrated_report_entire_

document.pdf. 

Oklahoma Department of Environmental Quality, 2014, 

2014 Bacterial and turbidity total maximum daily loads 

for Oklahoma Streams in the Lower Arkansas river area 

(Draft): Oklahoma Department of Environmental Quality, 

151 p.

Petersen, T.M., Rifai, H.S., Suarez, M.P., and Stein, A.R., 

2005, Bacteria loads from point and nonpoint sources in an 

urban watershed: Journal of Environmental Engineering, v. 

131, no. 10, p. 1414–1425.

Poteau Valley Improvement Authority, 2009, Restoring Wister 

Lake—PVIA’s strategic plan to improve water quality and 

enhance the lake ecosystem: Poteau Valley Improvement 

Authority, accessed February 26, 2013, at http://www.pvia.

org/wp-content/uploads/2009/11/0.2.ExecSum.10-26-09.

pdf. 

Pritt, J.W., and Raese, J.W., 1995, Quality assurance/quality 

control manual—National Water Quality Laboratory: U.S. 

Geological Survey Open-File Report 94–26, 15 p. 

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

of streamflow—Volume 2, computation of discharge: U.S. 

Geological Survey Water-Supply Paper 2175, v. 2, 285 p.

Ries, K.G., and Friesz, P. J., 2000, Methods for estimating 

low-flow statistics for Massachusetts streams: U.S. 

Geological Survey Water-Resources Investigations Report 

00–4135, 81 p.

Risley, J.C., Stonewall, Adam, and Haluska, T.L., 2008, 

Estimating flow-duration and low-flow frequency statistics 

for unregulated streams in Oregon: U.S. Geological Survey 

Scientific Investigations Report 2008–5126, 22 p.

Runkel, R.L., Crawford, C.G., and Cohn, T.A., 2004, Load 

estimator (LOADEST)—A FORTRAN program for 

estimating constituent loads in streams and rivers: U.S. 

Geological Survey Techniques and Methods, book 4, 

chapter 5, accessed January 4, 2014, at http://pubs.usgs.gov/

tm/2004/tm4A5.

State of Oklahoma, 2006, Title 785, Oklahoma Water 

Resources Board, chapter 46, implementation of 

Oklahoma’s water quality standards, unofficial 785—46: 

Oklahoma Water Resources Board, 44 p., accessed March 5, 

2014, at http://www.owrb.ok.gov/util/rules/pdf_rul/Chap46.

pdf.

Storm, D.E., White, Michael, Smolen, M.D., and Zang, Hailin, 

2001, Modeling total phosphorus loading for the Lake 

Eucha Basin: Stillwater, Okla., Oklahoma State University, 

Biosystems and Agriculture Engineering Department, 14 p. 

Tortorelli, R.L., 2008, Nutrient concentrations, loads, 

and yields in the Eucha-Spavinaw Basin, Arkansas and 

Oklahoma, 2002–2006: U.S. Geological Survey Scientific 

Investigations Report 2008–5174, 56 p.

Tortorelli, R.L., 2009, Water use in Oklahoma 1950–2005: 

U.S. Geological Survey Scientific Investigations Report 

2009–5212, 49 p.
34 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

U.S. Census Bureau, 2012, County population estimates—

U.S. Census Bureau population estimates: U.S. Census 

Bureau, accessed December 15, 2013, at http://www.census.

gov/popest/data/counties/totals/2012/CO-EST2012-01.html.

U.S. Department of Agriculture, 2007, The census of 

agriculture—2007 Census report: U.S. Department of 

Agriculture, accessed December 15, 2013, at http://www.

agcensus.usda.gov/Publications/2007/Full_Report/Census_

by_State/.

U.S. Environmental Protection Agency, 2009, National water 

quality inventory—Report to Congress, 2004 reporting 

cycle: U.S. Environmental Protection Agency, Office of 

Water, 841-R-08-001, 37 p.

U.S. Environmental Protection Agency, 2013, Overview of 

impaired waters and total maximum daily loads program: 

U.S. Environmental Protection Agency, accessed May 19, 

2014, at http://water.epa.gov/lawsregs/lawsguidance/cwa/

tmdl/overviewoftmdl.cfm.

U.S. Geological Survey, 1999, The quality of our Nation’s 

waters—Nutrients and pesticides: U.S. Geological Survey 

Circular 1225, 82 p. 

U.S. Geological Survey, 2006, National field manual for 

the collection of water-quality data, collections of water 

sample: U.S. Geological Survey Techniques of WaterResources Investigations Reports, book 9, chap. A4, 166 p., 

accessed November 20, 2013, at http://water.usgs.gov/owq/

FieldManual/chapter4/pdf/Chap4_v2.pdf.

U.S. Geological Survey, 2013, USGS water data for 

Oklahoma: U.S. Geological Survey, accessed December 15, 

2013, at http://water.usgs.gov/ok/nwis.

Wahl, K.L., and Tortorelli, R.L., 1997, Changes in flow in the 

Beaver-North Canadian River Basin upstream from Canton 

Lake, western Oklahoma: U.S. Geological Survey WaterResources Investigations Report 96–4304, 58 p.

Wahl, K.L., and Wahl, T.L., 1988, Effects of regional 

groundwater declines on streamflows in the Oklahoma 

Panhandle—Symposium on water-use data for water 

resources management: Tucson, Arizona, American Water 

Resources Association, p. 239–249.

Wilson, Lee, 1972, Seasonal suspended sediment yield 

patterns of U.S. rivers: Water Resources Research, v. 8, no. 

6, p. 1470–1479, doi: 10.1029/WR008i006p01470.
Appendixes 1–3 35

Appendixes 1–3
36 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13
Appendixes 1–3 37

Appendix 1. Instantaneous streamflows, total phosphorus concentrations, total nitrogen concentrations, suspended sediment 

concentrations, bacteria concentrations, and flow category for Poteau River at Loving, Oklahoma, from 2010 to 2013.

[ft3/s, cubic feet per second; mg/L, milligrams per liter; mL, milliliter; <, less than; >, greater than. All water-quality data available at

http://water.usgs.gov/ok/nwis]

Date Sample 

time

Streamflow 

(ft3/s)

Total 

phosphorus

concentration 

(mg/L as P)

Total 

nitrogen

concentration 

(mg/L as N)

Enterococcus sp. 

concentration

(colonies per 

100 mL)

Escherichia 

coli

(colonies per 

100 mL)

Suspended 

sediment

(mg/L)

Flow 

type

10/19/2010 1600 61 0.152 1.1 9 Base flow

12/9/2010 1600 7 0.047 <0.50 5 Base flow

3/7/2011 1455 17 0.057 0.85 12 Base flow

4/11/2011 1530 32 0.07 0.59 370 20 28 Base flow

4/15/2011 1330 1,400 0.391 1.7 >4,800 14,000 315 Runoff

4/20/2011 1430 73 0.097 0.91 460 40 22 Base flow

4/26/2011 1200 10,400 0.187 1 >4,800 3,100 88 Runoff

5/2/2011 1330 7,070 0.461 1.4 >4,800 9,600 66 Runoff

5/23/2011 1430 323 0.302 1.2 220 200 50 Runoff

6/7/2011 1200 30 0.062 <0.50 1,300 63 14 Base flow

8/16/2011 900 12 0.068 0.53 1,500 170 Runoff

10/4/2011 930 0.67 0.043 0.5 96 63 3 Base flow

11/9/2011 1330 1,340 0.401 2.4 >4,800 6,100 197 Runoff

11/22/2011 1430 17,200 0.428 1.6 >4,800 8,400 554 Runoff

12/5/2011 1345 5,050 0.236 1.4 >4,800 1,800 74 Runoff

12/8/2011 915 1,160 0.076 1 120 310 14 Base flow

2/7/2012 930 745 0.06 0.7 40 120 Runoff

3/12/2012 1130 3,500 0.317 0.93 >4,800 5,000 114 Runoff

3/21/2012 1145 6,490 0.258 0.96 >4,800 3,700 94 Runoff

4/10/2012 930 64 0.047 0.51 46 63 11 Base flow

6/12/2012 1530 1.5 0.055 0.63 >4,800 <10 10 Base flow

6/13/2012 1030 1.9 0.051 0.54 >4,800 31 7 Base flow

8/16/2012 830 0.82 0.052 0.66 260 52 5 Base flow

10/17/2012 1100 77 0.204 1.7 1,200 340 44 Runoff

10/24/2012 1200 7.9 0.113 1.4 69 160 10 Runoff

12/18/2012 930 3.1 0.054 0.65 56 130 3 Base flow

1/14/2013 1000 1,010 0.309 1.7 >4,800 3,100 86 Runoff

1/31/2013 1100 777 0.299 1.6 >4,800 8,700 60 Runoff

3/7/2013 1000 122 0.052 <0.50 13 <10 11 Base flow

3/11/2013 1400 1,880 0.229 1.1 1,800 2,100 73 Runoff

4/3/2013 1315 7,110 0.413 1.1 >4800 9,100 234 Runoff

4/24/2013 1530 149 0.051 0.52 350 63 12 Base flow

5/22/2013 1045 2,620 0.438 1.8 >4,800 6,900 134 Runoff

6/26/2013 1330 59 0.083 0.72 15 Base flow

8/14/2013 1200 1,410 0.241 1.2 4,000 860 82 Runoff

8/28/2013 900 36 0.057 <0.50 37 41 15 Base flow
38 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

Appendix 2. Instantaneous streamflows, total phosphorus concentrations, total nitrogen concentrations, suspended sediment 

concentrations, bacteria concentrations, and flow category for Poteau River near Heavener Oklahoma from 2010 to 2013.

[ft3/s, cubic feet per second; mg/L, milligrams per liter; mL, milliliter; <, less than; >, greater than. All water-quality data available at

http://water.usgs.gov/ok/nwis]

Date Sample 

time

Streamflow 

(ft3/s)

Total 

phosphorus

concentration 

(mg/L as P)

Total 

nitrogen

concentration 

(mg/L as N)

Enterococcus sp. 

concentration

(colonies per 

100 mL)

Escherichia 

coli

(colonies per 

100 mL)

Suspended 

sediment

(mg/L)

Flow type

10/27/2010 1300 56 0.114 0.94 500 82 23 Base flow

12/15/2010 1230 12 0.023 <0.50 40 10 17 Base flow

2/23/2011 1300 117 0.05 0.57 19 63 21 Base flow

4/11/2011 1330 93 0.053 0.5 190 97 23 Runoff

4/15/2011 1200 1,490 0.21 1.2 >4,800 3,200 295 Runoff

4/20/2011 1230 239 0.075 0.69 240 73 29 Runoff

4/26/2011 1500 16,400 0.263 1.1 >4,800 2,200 21 Runoff

5/2/2011 1445 15,400 0.3 1.1 >4,800 1,900 295 Runoff

5/23/2011 1245 517 0.134 0.83 80 97 33 Runoff

6/7/2011 1045 75 0.073 <0.50 43 63 24 Base flow

8/16/2011 1115 0.64 0.062 0.54 24 41 Runoff

10/4/2011 1045 1 0.047 0.57 17 41 8 Base flow

11/9/2011 1215 3,190 0.221 1.5 >4,800 2,200 195 Runoff

11/22/2011 1045 49,400 0.26 1.4 >4,800 6,300 658 Runoff

12/5/2011 1130 11,000 0.187 1.3 >4,800 290 69 Runoff

12/8/2011 1100 1,970 0.059 1 200 250 17 Base flow

1/25/2012 1700 22,000 0.256 1.1 >4,800 4,300 136 Runoff

2/7/2012 1115 1,090 0.051 0.65 63 220 11 Runoff

3/12/2012 1300 8,130 0.245 0.99 >4,000 5,200 128 Runoff

3/21/2012 1445 12,100 0.2 0.82 2,400 1,300 95 Runoff

4/10/2012 1100 147 0.04 <0.50 10 10 9 Base flow

6/13/2012 1200 3.3 0.042 <0.50 15 10 9 Base flow

6/27/2012 1215 3.4 0.068 0.63 4 10 28 Base flow

8/16/2012 1000 0.13 0.057 0.72 76 10 7 Base flow

10/17/2012 1300 158 0.166 1.4 2 290 41 Runoff

10/24/2012 1300 24 0.099 1.2 110 74 16 Runoff

12/18/2012 1100 6.3 0.046 1.2 17 10 3 Base flow

1/14/2013 1145 1,390 0.304 1.7 >4,800 3,200 138 Runoff

1/31/2013 1330 1,500 0.238 1.5 520 9,900 61 Runoff

3/6/2013 1330 235 0.035 0.55 13 10 8 Base flow

3/11/2013 1630 3,480 0.213 1.1 1,700 2,400 69 Runoff

4/3/2013 1700 10,500 0.378 1.1 >4,800 7,000 478 Runoff

4/25/2013 1030 451 0.034 <0.50 37 120 11 Base flow

5/22/2013 1230 5,380 0.189 0.98 >4,800 2,800 112 Runoff

6/26/2013 1200 117 0.084 0.74 16 Base flow

8/14/2013 1430 2,390 0.196 1.1 2,200 660 77 Runoff

8/28/2013 1130 82 0.065 0.51 6 73 23 Base flow
Appendixes 1–3 39

Appendix 3. Instantaneous streamflows, total phosphorus concentrations, total nitrogen concentrations, suspended sediment 

concentrations, bacteria concentrations, and flow category for Fourche Maline near Leflore, Oklahoma, from 2010 to 2013.

[ft3/s, cubic feet per second; mg/L, milligrams per liter; mL, milliliter; <, less than; >, greater than. All water-quality data available at

http://water.usgs.gov/ok/nwis]

Date

Sample 

time

Streamflow 

(ft3/s)

Total 

phosphorus

concentration 

(mg/L as P)

Total 

nitrogen

concentration 

(mg/L as N)

Enterococcus sp. 

concentration

(colonies per 

100 mL)

Escherichia 

coli

(colonies per 

100 mL)

Suspended 

sediment

(mg/L)

Flow type

10/27/2010 945 0.01 0.034 0.55 180 <10 23 Runoff

12/15/2010 1030 0.17 0.051 0.56 100 20 24 Runoff

2/23/2011 1030 12 0.045 0.58 27 160 28 Runoff

4/11/2011 1130 44 0.069 0.52 820 490 71 Base flow

4/15/2011 1030 2,230 0.33 1.8 >4,800 7,500 357 Runoff

4/20/2011 930 167 0.075 0.86 980 110 40 Runoff

4/26/2011 1730 5,690 0.287 1 >4,800 2,100 93 Runoff

5/2/2011 1400 5,310 0.14 0.89 >4,800 2,400 67 Runoff

5/23/2011 1000 1,450 0.172 1 1,800 1,400 102 Runoff

6/7/2011 830 37 0.09 0.64 87 41 23 Base flow

8/16/2011 1300 0.34 0.039 <0.50 60 <10 Runoff

11/9/2011 945 35 0.056 1,700 660 31 Runoff

11/22/2011 800 2,590 0.248 2.3 >4,800 24,000 281 Runoff

12/5/2011 930 948 0.137 1.7 410 1,300 104 Runoff

12/8/2011 1400 221 0.04 1.7 170 84 26 Base flow

1/25/2012 1400 6,540 0.336 1.5 3,500 4,000 168 Runoff

2/7/2012 1300 541 0.071 1.1 120 350 45 Base flow

3/12/2012 1000 8,130 0.057 0.65 340 870 Runoff

3/21/2012 900 5,480 0.182 1.1 4,000 10,000 78 Runoff

4/10/2012 1330 147 0.079 0.78 92 98 28 Base flow

6/13/2012 1400 15 0.058 0.51 150 30 18 Runoff

6/27/2012 1030 3.7 0.096 0.71 54 <10 48 Base flow

8/16/2012 1200 0.01 0.075 0.94 54 <10 15 Base flow

10/17/2012 1500 28 0.143 0.92 610 340 69 Runoff

10/24/2012 1015 0.27 0.063 0.64 130 <10 18 Runoff

1/14/2013 1430 13 0.066 0.55 88 74 10 Runoff

1/31/2013 1530 246 0.146 1.1 2,400 410 80 Runoff

3/6/2013 1300 61 0.062 0.85 37 31 23 Base flow

3/11/2013 1130 1,950 0.353 1.6 2,800 2,800 514 Runoff

4/3/2013 1030 3,500 0.294 1.2 4,000 8,600 Runoff

4/25/2013 1230 142 0.059 0.62 61 63 39 Base flow

5/21/2013 1430 6,230 0.717 2.5 >4,800 6,400 820 Runoff

5/22/2013 1330 3,020 0.204 1.1 >4,800 3,100 157 Runoff

6/26/2013 1530 20 0.058 0.6 9 Base flow

8/28/2013 1345 5 0.061 0.53 32 20 14 Base flow
40 Concentrations, Loads, and Yields and Bacteria Concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011–13

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