U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2009–3073

August 2009 Printed on recycled paper

Prepared in cooperation with the City of Wichita

Twelve Years of Monitoring Phosphorus and Suspended-Solids 

Concentrations and Yields in the North Fork Ninnescah River 

above Cheney Reservoir, South-Central Kansas 1997–2008

—by Mandy L. Stone, Jennifer L. Graham, and Andrew C. Ziegler

Cheney Reservoir, located on the North Fork Ninnescah 

River in south-central Kansas (fig. 1), is the primary water 

supply for the city of Wichita and an important recreational 

resource. Concerns about taste-and-odor occurrences in Cheney 

Reservoir have drawn attention to potential pollutants, including total phosphorus (TP) and total suspended solids (TSS). 

July 2009 was the 15th anniversary of the establishment of 

the Cheney Reservoir Watershed pollution management plan. 

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

city of Wichita, has collected water-quality data in the basin 

since 1996, and has monitored water quality continuously on 

the North Fork Ninnescah River since 1998. This fact sheet 

describes 12 years (1997–2008) of computed TP and TSS data 

and compares these data with water-quality goals for the North 

Fork Ninnescah River, the main tributary to Cheney Reservoir.

Introduction

Cheney Reservoir provides about 70 percent of the city 

of Wichita’s water supply (Christensen and others, 2006). The 

Cheney Reservoir Basin covers 933 square miles and predominantly is agricultural, and agricultural activities account for about 

65 percent of the phosphorus transported into Cheney Reservoir 

(Pope and others, 2002). The North Fork Ninnescah River contributes about 70 percent of the water flowing into the reservoir; 

however, there also are several small contributing tributaries 

(Christensen and others, 2006).

In response to 1990 to 1991 cyanobacterial-related tasteand-odor occurrences, a 

task force was formed in 

1992 to prepare a pollution 

management plan to identify and mitigate sources 

of water pollution in the 

Cheney Reservoir Watershed. The Cheney Reservoir Task Force identified 

TP and TSS, indicative 

of suspended-sediment 

concentrations, as primary 

pollutants of concern 

because of their relation to 

taste-and-odor producing 

cyanobacterial blooms. 

Consequently, mean stream 

water-quality goals for TP 

and TSS during base-flow, 

runoff, and long-term 

streamflow conditions 

were established (table 1) 

(Cheney Reservoir Task 

Force, 1994). TP goals 

were set at a similar standard as the State of Kansas 

for long-term stream water 

quality, and TSS goals 

Cheney

Reservoir

North

Fork

Ninnescah

River

Wolf Cr

Silver

Creek

Goose Creek

Red Rock

Arkansas River

Creek

RENO COUNTY

KINGMAN

COUNTY

EDWARDS

COUNTY

KIOWA

COUNTY

PAWNEE COUNTY

PRATT

COUNTY

Stafford Sylvia Abbyville

Penalosa

Arlington

Pretty Prairie

Haven

Kingman

Pratt

Langdon

Castleton

Turon

Hutchinson

SEDGWICK

COUNTY

Zenith

STAFFORD

COUNTY

07144780

07144780

Cheney

Reservoir

North

Fork

Ninnescah

River

Wolf Cr

Silver

Creek

Goose Creek

Red Rock

Arkansas River

Creek

0 5 10 15 20 MILES

0 5 10 15 20 KILOMETERS

RENO COUNTY

KINGMAN

COUNTY

EDWARDS

COUNTY

KIOWA

COUNTY

PAWNEE COUNTY

PRATT

COUNTY

Stafford Sylvia Abbyville

Penalosa

Arlington

Pretty Prairie

Haven

Kingman

Pratt

Langdon

Castleton

Turon Preston

99° 45' 30' 15' 98° 97°45'

38°

37°45'

50

54

61 14

14

17

96

Base from U.S. Bureau of Census digital data, 1992, scales vary from 1:24,000 to 1:100,000

Geographic projection and U.S. Geological Survey digital data, 1983, 1:100,000

Universal Transverse Mercator projection, Zone 14

Converted to Albers Equal-Area Conic projection

Standard parallels 29°30'N and 45°30'N, central meridian -96°00'W

Hutchinson

SEDGWICK

COUNTY

Zenith

STAFFORD

COUNTY

07144780

EXPLANATION

Developed land

Forest

Grassland/pasture

Cultivated crops

Wetlands

Water

Land use

07144780

Boundary of Cheney Reservoir Basin

Streamflow-gaging/water-quality sampling

 site and identification number

Land-use data from Multi-Resolution Land Characteristics Consortium

National Land-Cover Database, 2001

Crow Cr Crow Cr

Index map

Cheney

Reservoir

Basin

Wichita

KANSAS

Partridge

Irish Cr

Irish Cr

Figure 1. Cheney Reservoir Basin and the streamflow-gaging and water-quality monitoring site on the North 

Fork Ninnescah River, south-central Kansas.
were established to extend the life of Cheney Reservoir from 

130 to 200 years (Cheney Reservoir Task Force, 1994). From 

1994 to 2009, approximately 1,500 best management practice 

(BMP) contracts have been implemented in the Cheney Reservoir Basin (Cheney Reservoir Citizens Management Committee, 

written commun., 2009) and Conservation Reserve Program 

land has increased by approximately 69,684 acres (Starzec and 

others, 2008).

Total Phosphorus and Total Suspended-Solids 

Concentrations and Yields

Approach

•	 Streamflow has been measured continuously on the North 

Fork Ninnescah River above Cheney Reservoir (USGS 

streamflow-gaging station 07144780) since July 1965, and 

water-quality sensors (specific conductance, pH, water 

temperature, turbidity, and dissolved oxygen) have been 

operated continuously since October 1998. Collection of 

discrete and continuous water-quality data currently (2009) 

is scheduled to continue until 2015.

•	 TP and TSS concentrations in the North Fork Ninnescah 

River above Cheney Reservoir have been computed using 

continuous data for the past 12 years (1997–2008) based 

on regression equations developed from discrete waterquality samples. TP and TSS concentrations during 1997 

and 1998 were computed based on regression models 

using streamflow (Pope and Milligan, 2000). During 1999 

to 2008, regression equations were used to compute TP 

concentrations based on streamflow and turbidity, and TSS 

concentrations based on turbidity (Christensen and others, 

2006).

•	 Base-flow and runoff conditions were defined for each year 

based on annual discharge duration curves with a 10 percent flow separation point.

•	 All data are available on the World Wide Web at http://

ks.water.usgs.gov/ and http://nrtwq.usgs.gov/ks

Results

Streamflow 

•	 During 1997 to 2008 there were only two 50 percent 

exceedance floods (statistically, floods will occur every 

2 years), which occurred in 2000 and 2007. 

•	 In all years, mean annual streamflow was similar to or 

below the long-term average (fig. 2).

•	 2006 was one of the driest years on record—it had the third 

lowest annual flow for the period of record, and the lowest 

annual flow since 1972.

Total Phosphorus 

•	 Computed mean annual TP concentrations for the North 

Fork Ninnescah River ranged from 0.114 to 0.215 milligram per liter during 1997 to 2008 (fig. 2). 

•	 Computed mean base-flow and annual TP concentrations 

exceeded the base-flow goal of 0.05 milligram per liter 

and the long-term goal of 0.1 milligram per liter each 

year (fig. 2). Mean annual runoff TP concentrations never 

exceeded the runoff goal of 0.4 milligram per liter (fig. 2); 

hourly values indicate that the runoff goal was exceeded 

about 2 percent of the time during 1997 to 2008.

•	 During extreme low-flow conditions in 2006, the mean 

annual base-flow TP concentration was more than double 

the base-flow goal and approximately 10 percent greater 

than the long-term goal.

•	 Estimated annual TP yields ranged from 15 to 100 pounds 

per square mile, and generally were largest in years with 

the largest mean annual streamflow (figs. 2 and 3).

Table 1. Cheney Reservoir Task Force mean stream waterquality goals for total phosphorus and total suspended-solids 

concentrations in Cheney Reservoir Basin streams during baseflow, runoff, and long-term streamflow conditions.

Water-quality 

constituent

Mean water-quality goal 

(milligrams per liter)

Base-flow Runoff Long-term

Total phosphorus 0.05 0.4 0.1

Total suspended solids 20 550 100

U.S. Geological Survey streamflow-gaging station. Photograph by Jennifer 

Graham, U.S. Geological Survey.
Total Suspended Solids

•	 Computed mean annual TSS concentrations for the North 

Fork Ninnescah River ranged from 48 to 81 milligrams per 

liter during 1997 to 2008 (fig. 2).

•	 Computed mean base-flow and annual TSS concentrations 

exceeded the base-flow goal of 20 milligrams per liter each 

year, but not the long-term goal of 100 milligrams per liter 

(fig. 2). Mean annual runoff TSS concentrations never 

exceeded the runoff goal of 550 milligrams per liter, and 

hourly values indicate that the runoff goal was exceeded 

less than 1 percent of the time during 1997 to 2008.

•	 Estimated annual TSS yields within the North Fork Ninnescah River Basin ranged from 8,000 to 63,000 pounds per 

square mile, and generally were largest in years with the 

largest mean annual streamflow (figs. 2 and 3).

•	 During extreme low-flow conditions in 2006, the average 

annual TSS concentration was more than double the baseflow goal.

Conclusions

•	 Streamflow in most years during 1997 to 2008 was less 

than the long-term average and large flood events did not 

occur. Future TP and TSS concentrations and yields are 

likely to be more variable than observed during the dry 

period from 1997 to 2008. 

•	 Based on 1997 to 2008 data, base-flow TP and TSS goals and 

long-term TP goals are not being met; however, long-term 

TSS and runoff TP and TSS goals were rarely exceeded.

•	 Decreases in annual TP and TSS concentrations in the 

North Fork Ninnescah River were not discernable during 

1997 to 2008, due in part to large among-year hydrologic 

variability.

•	 Given that TP and TSS concentrations exceeded baseflow goals in 2006, an extremely dry year, the established 

base-flow goals may be unattainable or significantly more 

BMPs would be needed to attain them. 

 0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0

50

100

150

200

250

300

350

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

0

100

200

300

400

500

600

700

800

900

1,000

STREAMFLOW, IN CUBIC FEET PER SECOND

TOTAL PHOSPHORUS,

IN MILLIGRAMS PER LITER

TOTAL SUSPENDED SOLIDS,

IN MILLIGRAMS PER LITER

Runoff goal = 550

EXPLANATION

Base-flow

Runoff

Annual

Mean annual 

 (1966–2008)

 Base-flow

 Runoff

 Discharge

Goal

 Base-flow

 Runoff

 Long-term

Figure 2. Mean annual streamflow, computed total phosphorus, 

and computed total suspended-solids concentrations during 

base-flow, runoff, and long-term streamflow conditions in the 

North Fork Ninnescah River during 1997 to 2008.

0

20

40

60

80

100

120

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

TOTAL PHOSPHORUS, 

IN POUNDS PER SQUARE MILE

TOTAL SUSPENDED SOLIDS,

IN POUNDS PER SQUARE MILE

Goal

 Base-flow

 Long-term

Runoff goal = 635

Runoff goal = 872,920

EXPLANATION

Figure 3. Mean annual total phosphorus and total suspendedsolids yields in the North Fork Ninnescah River Basin during 1997 

to 2008.
North Fork Ninnescah River, south-central Kansas. Photograph by Bea Ritchie, U.S. Geological Survey.

•	 About 76 percent of the sediment load to Cheney Reservoir 

comes from 10 percent of the basin (U.S. Department of 

Agriculture, 2006); therefore, focused BMP implementation in areas of the basin with the greatest impacts on loads 

may result in documentable decreases in TSS, and likely 

TP, concentrations in the North Fork Ninnescah River.

•	 The effects of BMP implementation on water quality in the 

North Fork Ninnescah River and Cheney Reservoir may 

not be evident for many years. Continued monitoring will 

allow documentation of changing water-quality conditions.

References 

Cheney Reservoir Task Force, 1994, Watershed pollution 

management plan for North Fork Ninnescah Watershed and 

Cheney Reservoir, Final Report, 22 p.

Christensen, V.G., Graham, J.L., Milligan, C.R., Pope, L.M., 

and Ziegler, A.C., 2006, Water quality and relation to tasteand-odor compounds in the North Fork Ninnescah River and 

Cheney Reservoir, south-central Kansas, 1997–2003: U.S. 

Geological Survey Scientific Investigations Report 2006–

5095, 43 p.

Pope, L.M., and Milligan, C.R., 2000, Preliminary assessment 

of phosphorus transport in the Cheney Reservoir watershed, 

south-central Kansas, 1997–98: U.S. Geological Survey 

Water-Resources Investigations Report 2000–4023, 29 p.

Pope, L.M., Milligan, C.R., and Mau, D.P, 2002, Historical contributions of phosphorus from natural and agricultural sources 

and implications for stream water quality, Cheney Reservoir 

Watershed, south-central Kansas: U.S. Geological Survey 

Water-Resources Investigations Report 2002–4021, 25 p.

Starzec, K., French, L., Nelson, N., and Devlin, D., 2008, 

Conservation and citizen participation in the Cheney Lake 

watershed: Journal of Soil and Water Conservation, Nov/Dec 

2008, 63(6), 4 p.

U.S. Department of Agriculture Natural Resources Conservation Service, 2006, Ephemeral gully erosion in Cheney Lake 

Watershed, Kansas: Natural Resources Conservation Service 

CEAP Conservation Insight, 4 p. 

For more information concerning this publication, contact:

Director

U.S. Geological Survey 

Kansas Water Science Center

4821 Quail Crest Place

Lawrence, KS 66049

(785) 842–9909

Or visit the Kansas Water Science Center Web Site at:

http://ks.water.usgs.gov Publishing support provided by:

Rolla Publishing Service Center