Hydrologic and Water-Quality Characteristics for 

Bear Creek near Silver Hill, Arkansas, and Selected 

Buffalo River Sites, 1999-2004

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2004-5244
Front Cover: Photograph of Bear Creek looking upstream from Arkansas State Highway 74 

bridge near Snowball, Arkansas, November 2004. Photograph by Joel M. Galloway, U.S.

Geological Survey.
Hydrologic and Water-Quality 

Characteristics for Bear Creek near Silver 

Hill, Arkansas, and Selected Buffalo River 

Sites, 1999-2004

By Joel M. Galloway and W. Reed Green

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2004-5244
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004

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Contents

 iii

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

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

Purpose and Scope ...................................................................................................................................................................... 3

Description of Study Area ........................................................................................................................................................... 3

Methods ..................................................................................................................................................................................................... 3

Streamflow ..................................................................................................................................................................................... 3

Water Quality ................................................................................................................................................................................. 3

Hydrologic Characteristics ..................................................................................................................................................................... 5

Water-Quality Characteristics ............................................................................................................................................................... 9

Concentrations ............................................................................................................................................................................ 11

Loads and Yields.......................................................................................................................................................................... 11

Flow-Weighted Concentrations................................................................................................................................................ 26

Summary .................................................................................................................................................................................................. 30

References .............................................................................................................................................................................................. 30

Figures

1. Map showing locations of the Buffalo River, Bear Creek, and Calf Creek......................................................................... 2

2. Graphs showing daily base flow and total daily mean streamflow and water-quality sample times from January 

1999 through March 2004 for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River

near St. Joe, Arkansas ................................................................................................................................................................ 6

3. Graphs showing flow accumulation curves for January 1999 through March 2004 for Bear Creek near Silver Hill,

the Buffalo River near Boxley, and the Buffalo River near St. Joe, Arkansas................................................................... 8

4-8. Boxplots showing distribution of:

4. Nitrogen concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River

near St. Joe, 1999-2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003............................................................ 12

5. Phosphorus concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo 

River near St. Joe, 1999-2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003.................................................. 13

6. Dissolved organic carbon concentrations for Bear Creek near Silver Hill and the Buffalo River near St. Joe,

1999-2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003.................................................................................... 14

7. Fecal indicator bacteria concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, and

the Buffalo River near St. Joe, 1999-2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003............................. 15

8. Suspended-sediment concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the

Buffalo River near St. Joe, 1999-2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003.................................... 16

9-12. Graphs showing:

9. Annual loads of nutrients, dissolved organic carbon, and suspended sediment for Bear Creek near Silver

Hill, the Buffalo River near Boxley, and the Buffalo River near St. Joe, Arkansas, 1999-2003 ................................. 18

10. Mean daily seasonal loads of nutrients, dissolved organic carbon, and suspended sediment for Bear Creek

near Silver Hill, the Buffalo River near Boxley, and the Buffalo River near St. Joe, Arkansas, 1999-2003............. 22

11. Median annual nutrient yields for Bear Creek near Silver Hill, the Buffalo River near Boxley, the Buffalo River

near St. Joe, Arkansas, and other selected basins......................................................................................................... 27

12. Median annual nutrient flow-weighted concentrations for Bear Creek near Silver Hill, the Buffalo River near

Boxley, the Buffalo River near St. Joe, and other selected basins............................................................................... 29
iv 

Tables

1. Annual and monthly streamflow statistics for Bear Creek near Silver Hill, the Buffalo River near Boxley, and

the Buffalo River near St. Joe, 1999-2003, and Calf Creek near Silver Hill, Arkansas, 2001-2002 ................................. 7

2. Field parameters measured for Bear Creek near Silver Hill, the Buffalo River near Boxley, the Buffalo River near

St. Joe, 1999-2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003............................................................................ 9

3. Regression models applied to estimate constituent loads ................................................................................................. 17

4. Annual nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment loads and yields for Bear

Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River near St. Joe, Arkansas, 1999-2003 ..... 19

5. Seasonal nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment loads and yields for Bear

Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River near St. Joe, Arkansas, 1999-2003 ..... 23

6. Annual nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment flow-weighted concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River near St. Joe, Arkansas, 

1999-2003 ..................................................................................................................................................................................... 28
Hydrologic and Water-Quality Characteristics for Bear 

Creek near Silver Hill, Arkansas, and Selected Buffalo 

River Sites, 1999-2004

By Joel M. Galloway and W. Reed Green

Abstract

The purpose of this report is to describe and compare the 

hydrologic and water-quality characteristics of Bear Creek near 

Silver Hill, Arkansas, to two sites on the Buffalo River 

upstream from the confluence of Bear Creek, to a site on Calf 

Creek, a smaller tributary to the Buffalo River, to selected undeveloped sites across the Nation, and to a developed site in 

Arkansas. A better understanding of the hydrology and water 

quality of Bear Creek is of interest to many, including the 

National Park Service, which administers the Buffalo National 

River, to evaluate its effects on the hydrology and water quality 

of the Buffalo River.

The streamflow at Bear Creek near Silver Hill varied seasonally and annually from January 1999 to March 2004. The 

mean annual streamflow at Bear Creek for calendar years 1999 

to 2003 was 86.0 cubic feet per second. The highest annual 

mean streamflow occurred in 2002 (158 cubic feet per second) 

and the lowest annual mean streamflow occurred in 1999 (56.4 

cubic feet per second). The mean annual streamflow for calendar years 1999 to 2003 at the Buffalo River near Boxley and 

Buffalo River near St. Joe was 102 and 881 cubic feet per second, respectively. 

Concentrations of nitrogen measured for Bear Creek generally were greater than concentrations measured at the two 

Buffalo River sites and were similar to concentrations measured 

at Calf Creek. Concentrations of phosphorus measured at Bear 

Creek generally were greater than concentrations measured at 

the two Buffalo River sites and were similar to concentrations 

measured at Calf Creek. Fecal indicator bacteria concentrations 

generally were greater at Bear Creek than concentrations measured at the Buffalo River and similar to concentrations at Calf 

Creek. Bear Creek had significantly greater suspended-sediment concentrations than the Buffalo River near Boxley and the 

Buffalo River near St. Joe and similar concentrations to Calf 

Creek. 

Nutrients, dissolved organic carbon, and suspended-sediment loads at Bear Creek and two Buffalo River sites varied 

because of differences in land use and contributing drainage 

area for each site. In general, the Buffalo River near St. Joe had 

the greatest annual loads of nutrients, dissolved organic carbon, 

and suspended sediment. The Buffalo River near Boxley had 

the least annual nutrient and suspended-sediment loads among

the three sites. Buffalo River near Boxley had lesser annual 

loads than the other two sites probably because of the higher 

percentage of forested land in the basin and smaller contributing 

drainage area.

Mean annual nutrient, dissolved organic carbon, and suspended-sediment yields computed for Bear Creek were greater 

than yields computed for both of the Buffalo River sites. Bear 

Creek had greater median annual nutrient yields than selected 

undeveloped basins across the Nation and less median annual 

nutrient yields than the Illinois River south of Siloam Springs, 

Arkansas, which is representative of a developed basin.

Bear Creek had greater median annual flow-weighted 

nutrient concentrations than the Buffalo River near St. Joe, the 

Buffalo River near Boxley, and selected undeveloped sites 

across the Nation. Bear Creek had less median flow-weighted 

nutrient concentrations than the Illinois River.

Introduction

The Buffalo River and its tributary, Bear Creek, are in the 

White River Basin in the Ozark Plateaus physiographic province (Fenneman, 1938) in north-central Arkansas (fig. 1). The 

Buffalo River is a 150-mile long free-flowing stream famous 

for its scenic beauty and for canoeing, fishing, and other recreational activities. Eleven percent of the Buffalo River Basin lies 

within the boundaries of the Buffalo National River. Outside the 

boundary of the Buffalo National River, activities such as animal production and logging have increased, especially in the 

middle portion of the Buffalo River Basin (U.S. Department of 

Agriculture, 1995). Previous investigations indicated that nutrient and fecal-indicator bacteria concentrations and loads were 

elevated in Bear Creek and nearby Calf Creek (Mott, 1997; 

Petersen and others, 1998; Petersen and others, 2002; Steele and 

Mott, 1998; Galloway and Green, 2004). Increases in nutrients 

in the Buffalo River can lead to eutrophication of the stream that 

can be unfavorable for aesthetics and detrimental to the aquatic 

health of the stream. Increases in bacteria in the stream can pose 

a threat to humans that commonly come in contact with the 

waters for recreation. A better understanding of the hydrology 

and water quality of Bear Creek is of interest to many, including 

the National Park Service, which administers the Buffalo 

National River, to evaluate its effects on the hydrology and 

water quality of the Buffalo River. This report is part of the
SEARCY

COUNTY

NEWTON

COUNTY

B

e

a

r

Creek

Calf

Creek

Buffalo River

Buffalo

River

River

07055646

07055893

07056000

65

65

27

7

7

16

21

21

16

66

27

14

62

16

16

Boxley

Jasper

St. Joe

Marshall

Silver

Hill

White

07056515

Witts

Spring Fallsville

BOSTON MOUNTAINS

SPRINGFIELD PLATEAUS

AND

SALEM PLATEAUS

0 5 10 

0 5 10 Kilome

37°

35°42'

93°30' 92°30'

Base from U.S. Geological Surveydigital data, 1:100,000

07056000

EXPLANATIONBUFFALO NATIONAL RIVER

BOUNDARY

WATER-QUALITY AND STREAMFLOW MEASUREMENT SITE

AND ASSOCIATED STATION

IDENTIFICATION

Figure 1. Locations of the Buffalo River, Bear Creek, and Calf Creek.
Methods 3

National Park Service/U.S. Geological Survey Water-Quality 

Monitoring and Assessment Partnership.

Purpose and Scope

The purpose of this report is to describe and compare the 

hydrologic and water-quality characteristics of Bear Creek near 

Silver Hill, Arkansas, to two sites on the Buffalo River 

upstream from the confluence of Bear Creek, to a site on Calf 

Creek, a smaller tributary to the Buffalo River, to selected undeveloped sites across the Nation, and to a developed site in 

Arkansas. Stream stage was measured continuously to compute 

streamflow, and water-quality samples were collected monthly 

and during selected storm events. Data from February 1999 

through March 2004 are described in this report. Water samples 

were analyzed for several field parameters and constituents, 

including specific conductance, dissolved oxygen, water temperature, pH, alkalinity, fecal indicator bacteria, nutrients, 

organic carbon, and suspended sediment. Yields and loads of 

nutrients, dissolved organic carbon, and suspended sediment 

were estimated for Bear Creek and compared with yields and 

loads at sites on the Buffalo River upstream from its confluence 

with Bear Creek for calendar years 1999 through 2003. Flowweighted concentrations were calculated from mean annual 

streamflow and estimated annual loads for comparison with 

other developed and undeveloped basins.

Description of Study Area

The Buffalo River originates north of Fallsville, Arkansas, 

in the Boston Mountains and flows eastward into the Springfield and Salem Plateaus to the White River (fig. 1). The drainage area of the Buffalo River at its mouth is 1,340 square miles 

(Sullavan, 1974). The drainage area upstream from the Buffalo 

River near Boxley streamflow gaging station (07055646) is 

approximately 57 square miles and upstream from the Buffalo 

River near St. Joe streamflow gaging station (07056000) is 829 

square miles (Porter and others, 2001). Land use in the Buffalo 

River Basin is primarily a mixture of forest and pasture. 

Approximately 11 percent of the land is agricultural (mostly 

pasture) upstream from the Buffalo River near St. Joe. Only 

approximately 4 percent of the land is used for agriculture 

upstream from the Buffalo River near Boxley (Davis and Bell, 

1998).

Bear Creek lies in the middle part of the Buffalo River 

Basin and originates near Witts Spring, Arkansas, flowing 

northward to the Buffalo River (fig. 1). The Bear Creek drainage area is about 91.6 square miles at its mouth or about 10 percent of the Buffalo River drainage area just downstream from 

the confluence of Bear Creek (Petersen and others, 2002). Land 

use in the Bear Creek Basin includes forest (70 percent), pasture 

and hay (29 percent), and recreation (1 percent within the Buffalo National River boundary) (U.S. Geological Survey, 2002). 

The Bear Creek Basin shares a boundary to the west with the 

Calf Creek Basin (49.6 square miles). Land use in the Calf 

Creek Basin is 69 percent forest land and 31 percent pasture and 

hay (U.S. Geological Survey, 2002). 

Methods

Streamflow

Stream stage was measured continuously at a site on Bear 

Creek (07056515) and two sites on the Buffalo River (fig. 1). 

Stream stage was also measured continuously at a site on Calf 

Creek near Silver Hill, Arkansas (07055893) (Galloway and 

Green, 2004). Stage and instantaneous discharge were measured to compute the continuous streamflow from stage-discharge rating curves using methods described in Rantz and others (1982). 

Streamflow was separated using the Base Flow Index 

(BFI) hydrograph separation computer program to identify 

base-flow and surface-runoff components (Wahl and Wahl, 

1995). The BFI program uses the Institute of Hydrology method 

of base-flow separation, which divides the water year into increments and identifies the minimum flow for each increment. A 

3-day increment was used for Bear Creek and the Buffalo River 

near Boxley, and a 5-day increment was used for the Buffalo 

River near St. Joe because it has a larger drainage area. Minimums are compared to adjacent minimums to determine turning 

points on the base-flow hydrograph. If 90 percent of a given 

minimum is less than both adjacent minimums, then that minimum is a turning point. Straight lines are drawn between the 

turning points to define the base-flow hydrograph (Wahl and 

Wahl, 1995). The area beneath the hydrograph is the estimate of 

the volume of base flow for the period. The ratio of the baseflow volume to total flow volume is the base-flow index.

Water Quality

Water-quality samples were collected periodically at Bear 

Creek from February 1999 to March 2004. Samples were collected monthly and during 20 supplemental high-flow events 

during the period. Samples were collected periodically at the 

Buffalo River near Boxley site from April 1994 to April 2004 

and at the Buffalo River near St. Joe site from April 1974 to 

April 2004. Samples also were collected monthly at the Buffalo 

River sites. Supplemental high-flow samples were collected 

only at the Buffalo River near St. Joe site during calendar years 

2001 to 2004. Samples were collected from January 2001 to 

March 2003 at Calf Creek near Silver Hill (07055893); 15 samples were collected during high-flow conditions and 15 samples 

were collected during base-flow conditions (Galloway and 

Green, 2004).

Water-quality samples were collected following equalwidth increment methods using depth-integrated samplers and 

processed using protocols described in Wilde and Radke 

(1998), Wilde and others (1998a, 1998b, 1998c, 1999a, and 

1999b), and Meyers and Wilde (1999). Samples were analyzed 
4 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

for nutrients (total ammonia plus organic nitrogen, dissolved 

nitrite plus nitrate, total nitrogen, dissolved phosphorus, dissolved orthophosphorus, and total phosphorus), dissolved 

organic carbon, fecal indicator bacteria (fecal coliform, fecal 

streptococci, and E. coli), and suspended sediment. Field 

parameters, including water temperature, dissolved-oxygen 

concentration, alkalinity, pH, and specific conductance, also 

were collected with each sample following protocols described 

in Wilde and Radke (1998). Nutrient and dissolved organic carbon analyses were conducted at the U.S. Geological survey 

(USGS) National Water Quality Laboratory in Denver, Colorado, following procedures described in Fishman (1993). Samples were analyzed for fecal indicator bacteria in the field by 

USGS personnel, following procedures described in Meyers 

and Wilde (1999). Suspended sediment analyses were conducted at the USGS laboratory in Rolla, Missouri, following 

procedures described in Guy (1969).

To maintain proper quality assurance and control (QA/

QC) of water-quality data, protocols for instrument calibration 

(Wilde and Radke, 1998) and equipment cleaning (Wilde and 

others, 1998c) were followed. Associated blank and replicate 

water-quality samples also were collected periodically. Results 

indicated that cleaning procedures were adequate in preventing 

cross-contamination of samples and that the laboratory results 

were reproducible. QA/QC sample data were stored in the 

USGS National Water Information System (NWIS) database.

Water-quality samples were separated into those collected 

under base-flow or high-flow conditions. Base-flow waterquality samples were collected on days when the estimated base 

flow was greater than or equal to 70 percent of the total daily 

mean flow. High-flow samples were defined as water-quality 

samples collected on days when the surface-runoff component 

was greater than 30 percent of total daily mean flow. Waterquality samples collected for Calf Creek were separated into 

those collected under base-flow or high-flow conditions using 

the same methods (Galloway and Green, 2004).

The resulting streamflow and water-quality data were analyzed or summarized using several statistical and graphical 

techniques. Boxplots were used to compare concentrations of 

selected water-quality constituents among sites for data collected from February 1999 to March 2004. Concentrations 

reported as less than a laboratory reporting limit were converted 

to one-half the reporting limit for preparation of boxplots, calculation of total nitrogen concentrations (the sum of nitrite plus 

nitrate and ammonia plus organic nitrogen), and statistical analyses. The Wilcoxon rank sum test (Helsel and Hirsch, 1992) 

was used to test for differences in selected water-quality constituents among sites.

Water-quality constituent loads and yields were calculated 

from concentrations and streamflow measured at each site. A 

longer period of data for the Buffalo River near Boxley (1994 

to 2004) and near St. Joe (1990 to 2004) was used for calculating loads and yields than for Bear Creek (1999 to 2004). Constituent load (L) is a function of the volumetric rate of water 

passing a point in the stream (Q) and the constituent concentration within the water (C). Regression methods used to estimate 

constituent loads use the natural logarithm (ln) transformed 

relation between Q and C to estimate daily C (or L) of the constituent (Cohn and others, 1989; Cohn and others, 1992; Cohn, 

1995). The regression method can account for non-normal data 

distributions, seasonal and long-term cycles, censored data, 

biases associated with using logarithmic transformations, and 

serial correlations of the residuals (Cohn, 1995). The regression 

method uses discrete water-quality samples often collected over 

several years and a daily streamflow hydrograph. A typical loglinear regression model for estimating load can be expressed as:

ln( ) L βo β1 () β Q + 2 Q2 ( )β3T β4T2

β5 ( )β 2πT 6 sin + cos( ) 2πT

+ +

+

= + ln ln (1)

where L represents the constituent load, in pounds per day;

 is the regression constant;

, and are regression coefficients;

Q represents daily streamflow, in cubic feet per second;

and 

T represents decimal time.

However, no significant relations between seasonality or 

time to constituent concentration were found for the three sites. 

Therefore, only the relations between natural logarithmic-transformed L and Q were used:

ln( ) L = βo + β1 ln( ) Q (2)

Transforming the results of the model from logarithmic 

space to real space was accomplished using two methods: an 

adjusted maximum likelihood estimator (AMLE) and a least 

absolute deviation (LAD) (Cohn and others, 1992). The AMLE 

method was used if the constituent had censored values and the 

LAD method was used to transform the results if no censored 

values were included in the data or if outliers in the residuals 

were present. The S-LOADEST computer program (David 

Lorenz, U.S. Geological Survey, written commun., 2003) was 

used to estimate annual and seasonal constituent loads at the 

three sites for calendar years 1999 through 2003.

Annual yields (pounds per square mile) also were calculated from estimated annual loads at each site. The yield was 

calculated by dividing the annual load (pounds per year) by the 

drainage area (square miles) contributing flow at the location of 

the sampling site.

Flow-weighted concentrations also were calculated from 

the estimated annual loads. Flow-weighted concentrations were 

calculated by dividing the annual load by annual mean flow, 

and applying appropriate conversion factors for dimensional 

units:

CFW

L

QAnnual

----------------- 5.08 10–4 = × × (3)

where CFW represents the flow-weighted concentration, in

milligrams per liter,

L represents the annual constituent load in pounds per 

year, and

QAnnual represents the annual mean streamflow, in 

cubic feet per second.

βo

β1 β2 β3 β4 β5 ,,,, β6
Hydrologic Characteristics 5

Hydrologic Characteristics

Streamflow at Bear Creek near Silver Hill varied annually 

and seasonally from January 1999 to March 2004 (fig. 2 and 

table 1). The mean annual streamflow for Bear Creek for calendar years 1999 through 2003 was 86.0 cubic feet per second (ft3/

s). The highest annual mean streamflow occurred in 2002 (158 

ft3

/s) and the lowest annual mean streamflow occurred in 1999 

(56.4 ft3

/s). The highest streamflows occurred in the winter 

(December, January, and February) and spring (March through 

May). The lowest streamflows occurred in the summer (June 

through August) and fall (September through November). 

Additional daily mean streamflow data and summary statistics 

are presented in Porter and others (2001, 2002), Brossett and 

Evans (2003), and Evans and others (2004).

The streamflow at the Buffalo River near Boxley, the Buffalo River near St. Joe, and Calf Creek near Silver Hill also varied annually and seasonally (fig. 2 and table 1). The mean 

annual streamflow for calendar years 1999 through 2003 at the 

Buffalo River near Boxley and the Buffalo River near St. Joe 

were 102 ft3

/s and 881 ft3/s, respectively (table 1). At both sites, 

the highest annual mean streamflow occurred in 2002 and the 

lowest annual mean streamflow occurred in 2003. Mean annual 

streamflow at Calf Creek was 58.9 ft3

/s for calendar years 2001 

and 2002. Seasonal streamflow patterns at the Buffalo River 

and Calf Creek sites were similar to the patterns at the Bear 

Creek site.

The Bear Creek drainage basin composes approximately 

10 percent of the Buffalo River drainage basin at the confluence 

of Bear Creek and the Buffalo River. On an annual basis, the 

streamflow measured at the gaging station at Bear Creek near 

Silver Hill, which represents approximately 90 percent of Bear 

Creek drainage basin, was about 9 percent of the streamflow 

measured at the Buffalo River near St. Joe for calendar years 

1999 through 2003. In 1999, the streamflow at Bear Creek was 

about 7 percent of the streamflow measured at the Buffalo River 

near St. Joe and in 2002 the streamflow was about 12 percent of 

the streamflow measured at the Buffalo River near St. Joe. During periods of predominately base-flow conditions (August 

through November), the streamflow at Bear Creek was about 14 

to 16 percent of the streamflow measured at the Buffalo River 

near St. Joe, and during periods of high flow (February through 

June) the streamflow at Bear Creek was about 7 to 13 percent of 

the streamflow measured at the Buffalo River near St. Joe. 

Gains or losses in streamflow between the Bear Creek near Silver Hill gaging station and the mouth of Bear Creek (a distance 

of about 8 river miles) and between the Buffalo River near St. 

Joe gaging station and the confluence of the Buffalo River and 

Bear Creek (a distance of about 5 miles) are unknown.

Much of the total streamflow for Bear Creek, the Buffalo 

River near Boxley, and the Buffalo River near St. Joe occurred 

during relatively few days from January 1999 through March 

2004 (fig. 3). Fifty percent of the streamflow passed the gaging 

station at Bear Creek in 97 days (5 percent of the period) and the 

gaging stations at the Buffalo River near Boxley and the Buffalo 

River near St. Joe in 78 days (4 percent of the period). This suggests that during a typical year, the upper 50 percent of the 

streamflow passes the gaging station at Bear Creek in about 18 

days and passes the gaging stations at the Buffalo River near 

Boxley and the Buffalo River near St. Joe in about 15 days. If 

concentrations of materials transported were constant, regardless of the magnitude of flow, season, and other variables, more 

than one-half of the material transported past the site in a given 

year would occur over a period of less than 3 weeks.

The streamflow for Bear Creek and the two Buffalo River 

sites demonstrated a considerable amount of base flow that varied annually and seasonally (fig. 2). Bear Creek had the greatest 

percentage of base flow for the 5-year period (1999 through 

2003) with approximately 38 percent of the total streamflow 

contributed by base flow. The Buffalo River near Boxley had 

approximately 28 percent of the total streamflow contributed by 

base flow and the Buffalo River near St. Joe had approximately 

35 percent of the total streamflow contributed by base flow for 

the same period. The amount of base-flow contribution to the 

total annual streamflow for Bear Creek varied from 27 percent 

(2001) to 58 percent (2003). The contribution of base flow to 

the total annual streamflow ranged from 24 percent (2000 and 

2001) to 34 percent (2003) of the total annual streamflow for the 

Buffalo River near Boxley and ranged from 28 percent (2000) 

to 43 percent (1999) of the total annual streamflow for the Buffalo River near St. Joe. Seasonally, Bear Creek had a greater 

contribution of base flow during late summer and fall (August 

through November) with a percent contribution ranging from 

39 to 97 percent of the total monthly streamflow. The least percent contribution of base flow to Bear Creek generally occurred 

in the winter (December, January, and February) with a range 

of 10 to 70 percent of the total monthly streamflow. Although 

the least percent contribution of base flow to Bear Creek 

occurred in the winter, the greatest volume of base flow 

occurred in the late winter and early spring and the least volume 

of base flow occurred in the summer and early fall because of 

seasonal patterns of precipitation, evapotranspiration, and 

ground-water recharge in the basin. Similar seasonal patterns 

occurred for the two Buffalo River sites, although the Buffalo 

River near Boxley had the least percent contribution of base 

flow to the total monthly flow in May and June in addition to 

the winter months. 
6 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Figure 2. Daily base flow and total daily mean streamflow and water-quality sample times from January 1999 through March 2004 for Bear Creek near 

Silver Hill, the Buffalo River near Boxley, and the Buffalo River near St. Joe, Arkansas.
Table 1. Annual and monthly streamflow statistics for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River near St. Joe, 1999-2003, and CArkansas, 2001-2002.[Values are mean streamflow in cubic feet per second]

Station Year January February March April May June July August September October 

Bear Creek near Silver Hill 1999 80.9 86.3 151 172 35.0 41.5 35.2 5.94 3.50 3.52  2000 22.9 77.9 62.2 46.1 257 170 17.3 8.12 6.26 8.28 

2001 85.7 516 86.3 53.5 21.4 14.3 21.0 10.6 8.50 6.76 2002 322 265 713 319 118 32.6 31.1 12.2 5.61 4.34 2003 59.0 70.0 88.0 51.0 173 71.0 17.0 13.2 5.09 6.22 Mean for 1999-2003 114 205 220 128 121 66.0 24.0 10.0 5.79 5.82 Mean for period of record (1999-2003) 114 205 220 128 121 66.0 24.0 10.0 5.79 5.82 

Buffalo River near Boxley 1999 150 197 192 355 245 61.9 46.8 1.32 0.117 0.096 

2000 30.2 52.7 84.0 64.0 284 318 24.9 1.45 0.027 0.224 2001 137 531 75.2 50.0 24.4 35.0 10.3 8.13 6.09 30.9 2002 126 173 748 487 175 80.1 8.78 7.20 2.29 0.466 2003 9.46 47.1 145 56.4 310 36.7 8.11 2.51 1.26 4.28 Mean for 1999-2003 90.7 200 249 202 208 106 19.8 4.12 1.96 7.19 Mean for period of record (1994-1995; 1997-2003)

103 157 217 208 176 78.6 13.0 4.13 3.74 18.9 

Buffalo River near St. Joe 1999 1,200 1,470 1,700 2,410 1,620 467 737 57.0 34.3 23.0  2000 211 306 712 491 1,720 3,540 512 108 27.7 27.7 

2001 775 3,640 882 489 201 229 83.0 52.7 148 192 2002 1,270 2,320 6,800 3,450 1,200 643 251 125 38.7 26.2 2003 565 752 1,080 796 2,690 715 126 61 45.7 53.9 Mean for 1999-2003 805 1,700 2,230 1,530 1,490 1,120 342 81 59 64 Mean for period of record (1940-2003) 1,160 1,610 2,020 2,140 1,840 797 233 161 169 303 

Calf Creek near Silver Hill 2001 39.3 181 42.3 22.2 8.34 4.69 2.78 3.20 7.08 3.66  2002 87.6 99.6 456 163 63.3 15.7 17 5.29 1.62 1.79 

Mean for 2001-2002 63.4 140 249 92.6 35.8 10.2 9.89 4.25 4.35 2.73 Mean for period of record (2001-2002) 63.4 140 249 92.6 35.8 10.2 9.89 4.25 4.35 2.73 
PERCENT CUMULATIVE STREAMFLOW

PERCENT CUMULATIVE DAYS

BEAR CREEK NEAR SILVER HILL

0 10 20 30 40 50 60 70 80 90 100

0

10

20

30

40

50

60

70

80

90

100

BUFFFALO RIVER NEAR BOXLEY

0 10 20 30 40 50 60 70 80 90 100

0

10

20

30

40

50

60

70

80

90

100

BUFFALO RIVER NEAR ST. JOE

0 10 20 30 40 50 60 70 80 90 100

0

10

20

30

40

50

60

70

80

90

100

8 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Figure 3. Flow accumulation curves for January 1999 through March 2004 for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo 

River near St. Joe, Arkansas.
Water-Quality Characteristics 9

Water-Quality Characteristics

The water-quality characteristics of Bear Creek are 

described below in terms of concentrations, annual and seasonal 

loads and yields, and annual flow-weighted concentrations. The 

water quality of Bear Creek is compared to two Buffalo River 

sites and one Calf Creek (a smaller tributary to the Buffalo 

River) site. Field parameters collected with samples from the 

four sites are summarized in table 2. In addition, the yields and 

flow-weighted concentrations also are compared to other 

selected developed and undeveloped sites. 

Table 2. Field parameters measured for Bear Creek near Silver Hill, the Buffalo River near Boxley, the Buffalo River near St. Joe, 1999 -2004 and Calf 

Creek near Silver Hill, Arkansas, 2001-2003. 

[mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; °C, degrees Celsius; CaCO3, calcium carbonate; n, number of samples]

Station Sample type Statistic

Dissolved

 oxygen,

 in mg/L

Dissolved

 oxygen,

 percent

 saturation

pH,

 in

standard

units

Specific

 conductance,

 in μS/cm

at 25 ° C

Water 

temperature,

 in ° C

Alkalinity,

 in mg/L

as CaCO3

Bear Creek near Silver Hill High Flow (n=38) Maximum 14 130 8.7 374 22 172

Minimum 8.1 64 6.9 69.0 3.7 23

Mean 9.8 93 7.5 159 13 66

Median 9.4 93 7.6 131 12 54

Base flow (n=44) Maximum 13 118 8.3 433 29 188

Minimum 5.0 53 6.9 123 6.0 53

Mean 8.6 89 7.6 280 17 123

Median 8.5 90 7.6 300 19 126

All (n=82) Mean 9.2 91 7.6 224 15 96

Median 9.1 92 7.6 220 16 95

Buffalo River near Boxley High Flow (n=17) Maximum 13 106 8.1 194 24 92

Minimum 7.3 73 6.7 39.0 2.7 14

Mean 10 97 7.5 77.3 12 34

Median 10 98 7.6 64.0 11 28

Base flow (n=25) Maximum 13 105 8.5 201 26 103

Minimum 5.3 61 7.0 49.0 4.5 19

Mean 9.5 90 7.7 112 14 51

Median 9.3 96 7.5 112 11 48

All (n=42) Mean 9.8 93 7.6 97.9 13 44

Median 10 96 7.6 76.0 11 32
10 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Buffalo River near St. Joe High Flow (n=43) Maximum 16 140 8.4 277 29 132

Minimum 6.4 65 6.5 62.0 1.9 5

Mean 9.5 92 7.6 160 14 73

Median 9.5 91 7.7 154 13 69

Base flow (n=39) Maximum 13 115 8.6 266 29 159

Minimum 5.7 72 6.8 159 4.6 68

Mean 8.8 94 7.9 214 19 102

Median 8.8 92 8.0 219 21 102

All (n=82) Mean 9.2 92 7.8 186 16 87

Median 9.3 91 7.9 186 15 88

Calf Creek near Silver Hill High Flow (n=15) Maximum 16 140 8.2 389 25 171

Minimum 7.3 66 7.2 162 7.9 56

Mean 11 99 7.7 241 12 106

Median 11 95 7.8 236 11 98

Base flow (n=15) Maximum 13 154 8.6 365 25 178

Minimum 7 69 7.5 246 9.8 100

Mean 9.9 104 7.9 309 17 138

Median 10 101 7.8 319 16 144

All (n=30) Mean 10 101 7.8 275 15 122

Median 10 98 7.8 272 13 118

Table 2. Field parameters measured for Bear Creek near Silver Hill, the Buffalo River near Boxley, the Buffalo River near St. Joe, 1999 -2004 and Calf 

Creek near Silver Hill, Arkansas, 2001-2003.—Continued

[mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; °C, degrees Celsius; CaCO3, calcium carbonate; n, number of samples]

Station Sample type Statistic

Dissolved

 oxygen,

 in mg/L

Dissolved

 oxygen,

 percent

 saturation

pH,

 in

standard

units

Specific

 conductance,

 in μS/cm

at 25 ° C

Water 

temperature,

 in ° C

Alkalinity,

 in mg/L

as CaCO3
Water-Quality Characteristics 11

Concentrations

Concentrations of nitrogen in water samples collected at 

Bear Creek generally were greater than concentrations from the 

two Buffalo River sites and were similar to concentrations from 

Calf Creek (fig. 4). The median (50th percentile) total ammonia 

plus organic nitrogen concentration at Bear Creek was 0.12 milligrams per liter (mg/L) as nitrogen during base-flow conditions 

and 0.31 mg/L as nitrogen during high-flow conditions. Total 

ammonia plus organic nitrogen concentrations at Bear Creek 

were significantly greater (p < 0.05) than concentrations at both 

Buffalo River sites and Calf Creek during high-flow conditions 

and similar to the concentrations at the Buffalo River near St. 

Joe during base-flow conditions. The median nitrite plus nitrate 

concentration at Bear Creek was 0.47 mg/L as nitrogen during 

base-flow conditions and 0.38 mg/L as nitrogen during highflow conditions. Bear Creek had nitrite plus nitrate concentrations that were greater than concentrations at both the Buffalo 

River sites regardless of the flow condition. However, the nitrite 

plus nitrate concentrations at Bear Creek were greater than concentrations at Calf Creek during base-flow conditions and similar to concentrations at Calf Creek during high-flow conditions 

(fig. 4). 

Concentrations of phosphorus from water samples collected at Bear Creek generally were greater than concentrations 

at the two Buffalo River sites and were similar to concentrations 

at Calf Creek (fig. 5). Dissolved phosphorus and orthophosphorus concentrations were significantly greater at Bear and Calf 

Creeks than concentrations at the Buffalo River sites and did not 

noticeably differ with the flow condition. However, total phosphorus concentrations increased substantially during high-flow 

conditions at Bear Creek with a median concentration of 0.027 

mg/L as phosphorus during base-flow conditions and 0.078 mg/

L as phosphorus during high-flow conditions. Total phosphorus 

concentrations did not noticeably differ with flow conditions at 

Calf Creek. 

Concentrations of dissolved organic carbon from samples 

collected at Bear Creek generally were greater than concentrations at the Buffalo River near St. Joe and at Calf Creek (fig. 6). 

Dissolved organic carbon concentrations at Bear Creek were 

more than three times higher during high-flow conditions than 

during base-flow conditions (with a median value of 3.25 mg/L 

and 1.00 mg/L as carbon, respectively). Concentrations during 

high-flow conditions at the Buffalo River near St. Joe and Calf 

Creek were nearly twice as great as concentrations during baseflow conditions. Water-quality samples at the Buffalo River 

near Boxley were not analyzed for dissolved organic carbon.

Fecal indicator bacteria concentrations from samples collected at Bear Creek generally were greater than concentrations 

at the Buffalo River and similar to concentrations at Calf Creek 

(fig. 7). Bear Creek had a median concentration of 57 colonies 

per 100 milliliters (col./100 mL) for fecal coliform for all of the 

samples collected which was nearly eight times greater than the 

median concentration for the Buffalo River near Boxley and 

more than three times greater than the median concentration at 

Buffalo River near St. Joe. The median concentration of fecal 

streptococci at Bear Creek was 97 col./100 mL for all of the 

samples collected, which was about four times greater than the 

median concentrations at both Buffalo River sites. Bear Creek 

had a median E. coli concentration of 45 col./100 mL for all of 

the samples collected, which was more than seven times greater 

than the median concentration at the Buffalo River near Boxley 

and more than three times greater than median concentration at 

the Buffalo River near St. Joe.

Concentrations of fecal indicator bacteria were substantially greater at Bear Creek during high-flow conditions than 

during base-flow conditions (fig. 7). The fecal coliform concentrations during high-flow conditions at Bear Creek were 13 

times greater than concentrations during base-flow conditions 

and fecal streptococci concentrations were more than 15 times 

greater during high-flow conditions. E. coli concentrations at 

Bear Creek were 21 times higher during high-flow conditions 

than during base-flow conditions. 

Bear Creek had significantly greater suspended-sediment 

concentrations in all samples than the Buffalo River near Boxley and the Buffalo River near St. Joe, and similar concentrations to Calf Creek (fig. 8). Median concentrations of suspended 

sediment at Bear Creek did not substantially vary between samples collected at high-flow and base-flow conditions and were 

more than three times greater than median concentrations measured at the Buffalo River near Boxley regardless of the flow 

conditions (fig. 8).

Loads and Yields

Nutrients, dissolved organic carbon, and suspended-sediment loads and yields for Bear Creek and the two Buffalo River 

sites (table 3) varied because of differences in land use and contributing drainage area for each site. In general, the Buffalo 

River near St. Joe had the greatest annual loads of nutrients, dissolved organic carbon, and suspended sediment (fig. 9). The 

Buffalo River near Boxley had the least annual nutrient and suspended-sediment loads among the three sites. Greater loads 

would be expected at the Buffalo River near St. Joe because of 

the higher volume of streamflow that occurs at the site. Buffalo 

River near Boxley had lesser annual loads than the other two 

sites probably because of the smaller contributing area (lower 

volume of streamflow), and the higher percentage of forested 

land in the basin. Also, fewer samples representing high-flow 

events were collected at the Buffalo River near Boxley when 

generally most of the constituent load is delivered in a stream, 

which may affect the load computation for the site.
BUFFALO

RIVER

NEAR

ST. JOE

BEAR

CREEK

NEAR

SILVER

HILL

Baseflow

Stormflow

All samples

TOTAL AMMONIA PLUS

ORGANIC NITROGEN

DISSOLVED NITRITE

PLUS NITRATE

TOTAL NITROGEN

0.01

0.1

1

10

100

0.01

0.1

1

10

100

All samples

SITE AND CONSTITUENT

0.01

0.1

1

10

100

BUFFALO

RIVER

NEAR

BOXLEY

Base-Flow Samples

High-Flow

Samples

EXPLANATION

90th percentile

75th percentile

50th percentile

25th percentile

10th percentile

CONCENTRATION, IN MILLIGRAMS PER LITER AS NITROGEN

CALF

CREEK

NEAR

SILVER

HILL

b a

c

a c b

a a

a a

b

d

a b c c

a b c

a a

b

c

a

a b c

a b

a

a

b b

d

c

a

c Distributions associated

with the same letter

are not significantly

(p<0.05) different

Outlier

BUFFALO

RIVER

NEAR

ST. JOE

BEAR

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

BOXLEY

CALF

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

ST. JOE

BEAR

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

BOXLEY

CALF

CREEK

NEAR

SILVER

HILL

17 Number of samples

82

82

82

37

82

82

82

30 30 30

38

14

43

15 38

38

17

43 17

43

15 15

44

23

39

39

39

15 15

15

44 44

25 25

42

42

12 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Figure 4. Distribution of nitrogen concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River near St. Joe, 1999-

2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003.
SITE AND CONSTITUENT

CONCENTRATION, IN MILLIGRAMS PER LITER AS PHOSPHORUS

0.001

0.01

0.1

1

10

Base-flow

samples

0.001

0.01

0.1

1

10

High-flow

samples

0.001

0.01

0.1

1

10

All samples

DISSOLVED PHOSPHORUS ORTHOPHOSPHORUS TOTAL PHOSPHORUS

EXPLANATION

90th percentile

75th percentile

50th percentile

25th percentile

10th percentile

a

b c

a

a

b

b

a a

b c

a

c

a

c

a

a

c c

a

a b

a

a a

b

a

b

b

a

b

b

b

a

b

d

c Distributions associated

with the same letter

are not significantly

(p<0.05) different

Outlier

BUFFALO

RIVER

NEAR

ST. JOE

BEAR

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

BOXLEY

CALF

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

ST. JOE

BEAR

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

BOXLEY

CALF

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

ST. JOE

BEAR

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

BOXLEY

CALF

CREEK

NEAR

SILVER

HILL

82

21

82

30 82

82

42

82

30

30

82

42

9

38

43

15 15

15

38

38

43

43

17

17

17 Number of samples

44

12

39

15 44

44

39

39

15

15

25 25

 Water-Quality Characteristics 13

Figure 5. Distribution of phosphorus concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River near St. Joe, 

1999-2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003.
DISSOLVED ORGANIC CARBON CONCENTRATION, IN MILLIGRAMS PER LITER AS CARBON

0.1

1

10

100

BUFFALO

RIVER

NEAR

ST. JOE

CALF

CREEK

NEAR

SILVER

HILL

BEAR

CREEK

NEAR

SILVER

HILL

Base-Flow

Samples

Surface-flow

samples

All samples

0.1

1

10

100

High-Flow

Samples

0.1

1

10

100

All Samples

SITE

EXPLANATION

90th percentile

75th percentile

50th percentile

25th percentile

10th percentile

a Distributions associated

with the same letter

are not significantly

(p<0.05) different

a

a a

a b

a a b

b

Outlier

17 Number of samples

82

80 30

38

42 15

44 39

15

14 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Figure 6. Distribution of dissolved organic carbon concentrations for Bear Creek near Silver Hill and the Buffalo River near St. Joe, 1999-2004 and Calf 

Creek near Silver Hill, Arkansas, 2001-2003.
BACTERIA CONCENTRATION, IN COLONIES PER 100 MILLILITERS

0.1

1

10

100

1000

10000

100000

Base-Flow Samples

All samples

FECAL COLIFORM FECAL STREPTOCOCCI E. COLI

Surfacerunoff samples

0.1

1

10

100

1000

10000

100000

High-Flow Samples

0.1

1

10

100

1000

10000

100000

All Samples

SITE AND BACTERIA TYPE

EXPLANATION

90th percentile

75th percentile

50th percentile

25th percentile

10th percentile

c Distributions associated

with the same letter

are not significantly

(p<0.05) different

a a a

a a

a

a b

a b

a

b b a

b a

b

a

b b a b b a

b a b c a b b c a

c a

c

Outlier

,

,

,

,

,

,

,

,

,

BUFFALO

RIVER

NEAR

ST. JOE

BEAR

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

BOXLEY

CALF

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

ST. JOE

BEAR

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

BOXLEY

CALF

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

ST. JOE

BEAR

CREEK

NEAR

SILVER

HILL

BUFFALO

RIVER

NEAR

BOXLEY

CALF

CREEK

NEAR

SILVER

HILL

17 Number of samples

82

42 82 30 82 82 42 82 42 82 30

30

38

17

43 15 38

38

17 17

43 43 15

15

15

15

44 44 44 25 39 25 39 25 39

15

 Water-Quality Characteristics 15

Figure 7. Distribution of fecal indicator bacteria concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River near 

St. Joe, 1999-2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003.
0.1

1

10

100

1000

10000

0.1

1

10

100

1000

10000

BUFFALO

RIVER

NEAR

BOXLEY

SUSPENDED SEDIMENT CONCENTRATION, IN MILLIGRAMS PER LITER

0.1

1

10

100

1000

10000

BUFFALO

RIVER

NEAR

ST. JOE

CALF

CREEK

NEAR

SILVER

HILL

BEAR

CREEK

NEAR

SILVER

HILL

Base-flow Samples

High-flow Samples

All Samples

SITE

EXPLANATION

75th percentile

50th percentile

25th percentile

10th percentile

c Distributions associated

with the same letter

are not significantly

(p<0.05) different

a

a

a

b

b a

b

c b

c

c

a

Outlier

90th percentile

,

,

,

,

,

,

17 Number of samples

75

37

74

30

34 14

39

15

41 15

23

35

16 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Figure 8. Distribution of suspended-sediment concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, and the Buffalo River near 

St. Joe, 1999-2004 and Calf Creek near Silver Hill, Arkansas, 2001-2003.
 Water-Quality Characteristics 17

Table 3. Regression models applied to estimate constituent loads.

[Water-quality data collected between January 1994 and March 2004 for the Buffalo River near Boxley, January 1990 and March 2004 for the Buffalo River near 

St. Joe, and February 1999 and March 2004 for Bear Creek near Silver Hill. N is nitrogen, P is phosphorus, C is carbon, Regression model described by the equation , where L is load in pounds per day, Q is discharge, in cubic feet per second, is a regression constant, and is a regression 

coefficient; --, not calculated]

Constituent Site

Number of

samples

Regression

constant

(β0)

Regression

coefficient

(β1)

Coefficient of

determination

(R2)

Total ammonia plus

organic nitrogen as N

Buffalo River near Boxley 82 2.22 1.07 97

Buffalo River near St. Joe 113 5.77 1.32 94

Bear Creek near Silver Hill 82 2.81 1.38 93

Nitrite plus nitrate as N Buffalo River near Boxley 86 1.52 1.08 93

Buffalo River near St. Joe 113 5.36 1.26 89

Bear Creek near Silver Hill 82 3.88 0.89 91

Total nitrogen as N Buffalo River near Boxley -- -- -- --

Buffalo River near St. Joe 113 6.42 1.28 95

Bear Creek near Silver Hill 82 4.27 1.12 95

Dissolved phosphorus as P Buffalo River near Boxley -- -- -- --

Buffalo River near St. Joe 113 2.64 1.28 94

Bear Creek near Silver Hill 82 1.01 1.42 96

Orthophosphorus as P Buffalo River near Boxley -- -- -- --

Buffalo River near St. Joe 113 2.73 1.26 94

Bear Creek near Silver Hill 82 0.666 1.22 94

Total phosphorus as P Buffalo River near Boxley 85 -0.218 1.11 89

Buffalo River near St. Joe 160 3.7 1.46 85

Bear Creek near Silver Hill 82 1.52 1.42 95

Dissolved organic

carbon as C

Buffalo River near Boxley -- -- -- --

Buffalo River near St. Joe 107 8.15 1.22 96

Bear Creek near Silver Hill 81 5.04 1.35 96

Suspended sediment Buffalo River near Boxley 86 7.14 1.02 84

Buffalo River near St. Joe 110 10.94 1.38 86

Bear Creek near Silver Hill 74 8.07 1.23 83

ln( ) L βo β = + 1 lnQ βo β1
18 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Annual loads for 1999 through 2003 showed substantial 

variability among the three sites and through time (fig. 9 and 

table 4). Annual loads of total ammonia plus organic nitrogen 

for Bear Creek ranged from 35,700 pounds of nitrogen per year 

(lbs/yr) in 2003 to 192,000 lbs/yr in 2002. The greater loads in 

2002 can be attributed to the higher volume of streamflow in 

2002. The total ammonia plus organic nitrogen loads for the 

Buffalo River near St. Joe were 5 to more than 10 times greater 

than the loads for Bear Creek, and the loads for the Buffalo 

River near Boxley were one-sixth to one-half the loads for Bear 

Creek. Similarly, nitrite plus nitrate loads for the Buffalo River 

near St. Joe were four to six times greater than Bear Creek, and 

the Buffalo River near Boxley had loads that were one-sixth to 

one-third the loads for Bear Creek. Total nitrogen loads for Bear 

Creek ranged from 103,000 lbs/yr in 2003 to 302,000 lbs/yr in 

2002. Total phosphorus loads for Bear Creek ranged from 9,920 

lbs/yr in 2003 to 52,800 lbs/yr in 2002. The total phosphorus 

loads for the Buffalo River near St. Joe were 5 to 11 times 

greater than Bear Creek and the loads for the Buffalo River near 

Boxley were one-twelfth to one-third the loads for Bear Creek. 

The dissolved organic carbon loads for Bear Creek ranged from 

301,000 lbs/yr in 2003 to 1,540,000 lbs/yr in 2002. The dissolved organic carbon loads for the Buffalo River near St. Joe 

were 4 to more than 10 times greater than loads for Bear Creek. 

Samples collected for the Buffalo River near Boxley were not 

analyzed for dissolved organic carbon. Suspended-sediment 

loads for Bear Creek ranged from 10,000,000 lbs/yr in 2003 to 

40,200,000 lbs/yr in 2002. The Buffalo River near St. Joe had 

suspended-sediment loads that were 6 to 11 times greater than 

the loads for Bear Creek and the Buffalo River near Boxley had 

loads that were one-ninth to one-third the loads for Bear Creek. 

LOAD, IN POUNDS PER YEAR

EXPLANATION

NC LOAD NOT COMPUTED

TOTAL AMMONIA PLUS ORGANIC NITROGEN

AS NITROGEN

0

200000

400000

600000

800000

1000000

NITRITE PLUS NITRATE

AS NITROGEN

LOAD, IN POUNDS PER YEAR

0

100000

200000

300000

400000

500000

600000

700000

TOTAL NITROGEN AS NITROGEN

YEAR

0

500000

1000000

1500000

2000000

2500000

ORTHOPHOSPHORUS AS PHOSPHORUS

YEAR

1999 2000 2001 2002 2003

0

10000

20000

30000

40000

50000

60000

NC NC NC NC NC

NC NC NC NC NC

, ,

,

,

,

,

,

,

,

,

,

,

,

, ,

, ,

, ,

, ,

,

,

,

,

,

,

,

DISSOLVED PHOSPHORUS AS PHOSPHORUS

0

10000

20000

30000

40000

TOTAL PHOSPHORUS AS PHOSPHORUS

0

50000

100000

150000

200000

250000

300000

350000

NC NC NC NC NC

DISSOLVED ORGANIC CARBON AS CARBON

0

2000000

4000000

6000000

8000000

NC NC NC NC NC

SUSPENDED SEDIMENT

YEAR

1999 2000 2001 2002 2003

100000

1000000

10000000

100000000

1000000000

,

,

,

,

,

,

,

,

,

,

,

, ,

, ,

, ,

, ,

,

, , ,

, ,

, ,

, ,

BEAR CREEK NEAR

SILVER HILL

BUFFALO RIVER NEAR

BOXLEY

BUFFALO RIVER NEAR

ST. JOE

Figure 9. Annual loads of nutrients, dissolved organic carbon, and suspended sediment for Bear Creek near Silver Hill, the Buffalo River near Boxley, 

and the Buffalo River near St. Joe, Arkansas, 1999-2003.
Table 4. Annual nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment loads and yields for Bear Creek near Silver Hill, the Buffalo River near Box

St. Joe, Arkansas, 1999-2003.

[Loads and yields were rounded to three significant figures; lbs/yr, pounds per year; lbs/yr/mi2, pounds per year per square mile; SD, standard deviation; N, nitrogen; P, phospho

Bear Creek near Silver Hill 1999 40,100+/-101 53,100+/-130 104,000+/-223

2000 57,500+/-191 55,700+/-162 117,000+/-2702001 107,000+/-425 71,400+/-298 172,000+/-4482002 192,000+/-755 118,000+/-591 302,000+/-8172003 35,700+/-83 55,500+/-113 103,000+/-212

Buffalo River near Boxley 1999 21,900+/-771 17,000+/-107 --

2000 16,000+/-613 12,500+/-80 --2001 20,700+/-812 16,200+/-105 --2002 29,800+/-1,316 23,500+/-159 --2003 11,600+/-356 8,930+/-54 --

----

Buffalo River near St. Joe 1999 420,000+/-1,932 332,000+/-1,874 921,000+/-5,263

2000 418,000+/-2,315 302,000+/-1,737 919,000+/-5,5142001 483,000+/-2,750 344,000+/-1,995 1,060,000+/-6,4662002 950,000+/-5,922 642,000+/-3,837 2,090,000+/-13,4322003 228,000+/-1,287 629,000+/-3,587

Total ammonia plus organic 

nitrogen as N Nitrite plus nitrate as N Total nitrogen as N

Site Year

Load

(lbs/yr)(+/-SD)

Yield

(lbs/yr/mi2)

Load

(lbs/yr)(+/-SD)

Yield

(lbs/yr/mi2)

Load 

(lbs/yr)

(+/-SD)

Yield

(lbs/yr/mi2)

234 309 605335 324 680621 416 999

1,120 690 1,760

208 323 600

Mean 86,400 503 70,800 413 160,000 929Median 57,500 335 55,700 324 117,000 680

174 135 --128 100 --164 129 --237 187 --

92 71 --

Mean 20,000 159 15,600 124 --Median 20,700 164 16,200 129 --

230 182 504229 165 503264 188 581520 351 1,140

287,000+/-1,315 157 125 344

Mean 512,000 280 370,000 202 1,120,000 614Median 420,000 230 332,000 182 921,000 504
Table 4. Annual nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment loads and yields for Bear Creek near Silver Hill, the Buffalo River near Box

St. Joe, Arkansas, 1999-2003.—Continued

[Loads and yields were rounded to three significant figures; lbs/yr, pounds per year; lbs/yr/mi2, pounds per year per square mile; SD, standard deviation; N, nitrogen; P, phospho

Bear Creek near Silver Hill 1999 4,480+/-7 3,440+/-7 11,100+/-46

2000 5,570+/-10 4,280+/-11 15,900+/-902001 9,220+/-21 7,110+/-21 29,300+/-2042002 16,600+/-38 12,800+/-39 52,800+/-3632003 4,220+/-6 3,230+/-6 9,920+/-36

Buffalo River near Boxley 1999 -- -- 3,030+/-79

2000 -- -- 2,240+/-642001 -- -- 2,900+/-842002 -- -- 4,240+/-1392003 -- -- 1,590+/-36

-- ---- --

Buffalo River near St. Joe 1999 16,600+/-72 28,400+/-160 122,000+/-931

2000 16,000+/-82 24,900+/-142 131,000+/-1,1642001 18,400+/-97 28,200+/-163 153,000+/-1,3882002 35,600+/-207 50,800+/-307 310,000+/-3,0092003 11,400+/-48 19,800+/-111 83,300+/-641

Dissolved phosphorus as P Orthophosphorus as P Total phosphorus as P

Site Year

Load

(lbs/yr) (+/-SD)

Yield

(lbs/yr/mi2)

Load

(lbs/yr)(+/-SD)

Yield

(lbs/yr/mi2)

Load

(lbs/yr)(+/-SD)

Yield

(lbs/yr/mi2)

26 20 6532 25 9254 41 17197 74 30725 19 58

Mean 8,010 47 6,170 36 23,800 139Median 5,570 32 4,280 25 15,900 92

-- -- 24-- -- 18-- -- 23-- -- 34-- -- 13

Mean -- -- 2,800 22

Median -- -- 2,900 23

9 16 679 14 72

10 15 8419 28 170

6 11 46

Mean 19,600 11 30,400 17 160,000 87Median 16,600 9 28,200 15 131,000 72
Table 4. Annual nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment loads and yields for Bear Creek near Silver Hill, the Buffalo River near Box

St. Joe, Arkansas, 1999-2003.—Continued

[Loads and yields were rounded to three significant figures; lbs/yr, pounds per year; lbs/yr/mi2, pounds per year per square mile; SD, standard deviation; N, nitrogen; P, phospho

Bear Creek near Silver Hill 1999 335,000+/-613 10,700,000+/-70,630

2000 468,000+/-1,047 13,400,000+/-99,9822001 854,000+/-2,238 22,400,000+/-188,5042002 1,540,000+/-3,998 40,200,000+/-342,3952003 301,000+/-522 10,000,000+/-62,674

Buffalo River near Boxley 1999 -- 3,430,000+/-44,987

2000 -- 2,520,000+/-34,0822001 -- 3,250,000+/-44,7852002 -- 4,700,000+/-69,4512003 -- 1,820,000+/-22,023

----

Buffalo River near St. Joe 1999 3,430,000+/-10,307 121,000,000+/-982,852

2000 3,180,000+/-11,148 126,000,000+/-1,220,9332001 3,640,000+/-13,111 146,000,000+/-1,454,7592002 6,870,000+/-27,555 295,000,000+/-3,148,4072003 2,360,000+/-6,927 82,600,000+/-674,175

Dissolved organic carbon as C Suspended sediment

Site Year

Load

(lbs/yr)(+/-SD)

Yield

(lbs/yr/mi2)

Load 

(lbs/yr)(+/-SD)

Yield

(lbs/yr/mi2)

1,950 62,2002,730 78,0004,970 130,0008,950 234,0001,760 58,400

Mean 699,000 4,070 19,300,000 112,000Median 468,000 2,730 13,400,000 78,000

-- 27,300-- 20,000-- 25,800-- 37,400-- 14,400

Mean -- 3,140,000 25,000

Median -- 3,250,000 25,800

1,880 66,3001,740 69,0001,990 80,2003,760 161,0001,290 45,200

Mean 3,900,000 2,130 154,000,000 84,300Median 3,430,000 1,880 126,000,000 69,000
22 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Estimated nutrient, dissolved organic carbon, and suspended-sediment loads computed for Bear Creek and the Buffalo River varied seasonally for the period of 1999 to 2003 (fig. 

10 and table 5). The greatest loads for all three sites occurred in 

the winter and spring and the least loads occurred in the summer 

and fall. Mean daily total nitrogen loads for Bear Creek ranged 

from 69.6 pounds per day (lbs/d) in the fall to 795 lbs/d in the 

spring. Mean daily total phosphorus loads for Bear Creek 

ranged from 5.37 lbs/d in the fall to 121 lbs/d in the spring. Dissolved organic carbon mean daily loads for Bear Creek ranged 

from 165 lbs/d in the fall to 3,540 lbs/d in the spring, and suspended-sediment mean daily loads ranged from 5,940 lbs/d in 

the fall to 97,600 lbs/d in the spring.

BEAR CREEK NEAR

SILVER HILL

BUFFALO RIVER NEAR

BOXLEY

BUFFALO RIVER NEAR

ST. JOE

MEAN LOAD, IN POUNDS PER DAY

MEAN LOAD, IN POUNDS PER DAY

EXPLANATION

NC LOAD NOT COMPUTED

(GREATER THAN 80

PERCENT OF

CONCENTRATION DATA

BELOW LABORATORY

DETECTION LIMITS)

TOTAL AMMONIA PLUS ORGANIC NITROGEN AS NITROGEN

WINTER SPRING SUMMER FALL

1

10

100

1000

10000

NITRITE PLUS NITRATE AS NITROGEN

WINTER SPRING SUMMER FALL

1

10

100

1000

10000

TOTAL NITROGEN AS NITROGEN

WINTER SPRING SUMMER FALL

10

100

1000

10000

100000

ORTHOPHOSPHORUS AS PHOSPHORUS

SEASON

WINTER SPRING SUMMER FALL

0.1

1

10

100

1000

NC NC NC NC

NC NC NC NC

,

,

,

,

,

,

,

, ,

,

SUSPENDED SEDIMENT

SEASON

WINTER SPRING SUMMER FALL

1000

10000

100000

1000000

10000000

DISSOLVED ORGANIC CARBON AS CARBON

WINTER SPRING SUMMER FALL

10

100

1000

10000

100000

DISSOLVED PHOSPHORUS AS PHOSPHORUS

WINTER SPRING SUMMER FALL

0.1

1

10

100

1000

TOTAL PHOSPHORUS AS PHOSPHORUS

WINTER SPRING SUMMER FALL

1

10

100

1000

10000

NC NC NC NC

NC NC NC NC

,

,

,

,

,

,

,

,

,

,

,

Figure 10. Mean daily seasonal loads of nutrients, dissolved organic carbon, and suspended sediment for Bear Creek near Silver Hill, the Buffalo River 

near Boxley, and the Buffalo River near St. Joe, Arkansas, 1999-2003.
Table 5. Seasonal nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment loads and yields for Bear Creek near Silver Hill, the Buffalo River near Box

St. Joe, Arkansas, 1999-2003.

[Values are loads in pounds per day; N is nitrogen; P is phosphorus; C is carbon; winter defined as December through February; spring defined as March through May; summer fall defined as September through November; values were rounded to three significant figures; --, not calculated]

Total ammonia plus organic nitrogen as N Nitrite plus nitrate as N 

Site Year Winter Spring Summer Fall Winter Spring Summer Fall Winter 

Bear Creek near Silver Hill 1999 150 222 53.0 1.69 238 282 69.9 15.0 446 

2000 137 365 134 49.1 136 269 152 89.1 287 2001 694 68.0 12.5 5.87 396 144 47.6 30.5 1,040 2002 1,080 1,350 28.1 3.90 579 761 71.9 24.0 1,570 2003 127 187 40.7 35.4 166 253 91.2 67.7 324 Mean 437 438 53.7 19.2 303 342 86.4 45.3 732 Median 150 222 40.7 5.87 238 269 71.9 30.5 446 

Buffalo River near Boxley 1999 94.3 141 19.5 0.320 72.6 110 15.1 0.220 -- 

2000 33.2 78.0 60.6 17.5 25.4 61.2 47.8 13.5 -- 2001 120 26.0 9.12 18.5 93.8 19.3 6.69 14.1 -- 2002 113 254 16.5 0.740 89.1 202 12.3 0.510 -- 2003 11.4 91.9 8.03 9.83 8.46 71.6 5.89 7.34 -- Mean 74.4 118 22.8 9.38 57.9 92.8 17.6 7.13 -- Median 94.3 91.9 16.5 9.83 72.6 71.6 12.3 7.34 -- 

Buffalo River near St. Joe 1999 1,530 2,710 514 10.4 1,270 2,100 414 14.6 3,360 

2000 430 1,460 2,620 274 359 1,080 1,770 239 943 2001 2,590 475 72.6 171 1,830 442 79.3 166 5,690 2002 3,970 8,140 282 11.6 2,730 5,300 270 16.1 8,740 2003 424 2,180 236 211 368 1,640 219 183 929 Mean 1,790 2,990 745 136 1,310 2,110 550 124 3,930 Median 1,530 2,180 282 171 1,270 1,640 270 166 3,360 
Table 5. Seasonal nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment loads and yields for Bear Creek near Silver Hill, the Buffalo River near Box

St. Joe, Arkansas, 1999-2003.--Continued [Values are loads in pounds per day; N is nitrogen; P is phosphorus; C is carbon; winter defined as December through February; spring defined as March through May; summer 

fall defined as September through November; values were rounded to three significant figures; --, not calculated]

Dissolved phosphorus as P Orthophosphorus as P Total phosp

Site Year Winter Spring Summer Fall Winter Spring Summer Fall Winter Spring 

Bear Creek near Silver Hill 1999 18.1 24.9 5.62 0.360 13.9 19.1 4.31 0.270 41.7 61.5 

2000 13.6 32.4 14.1 6.04 10.5 25.0 10.8 4.63 37.8 101 2001 58.4 9.01 1.98 1.03 45.0 6.89 1.51 0.780 191 19.0 2002 89.6 115 3.86 0.727 69.1 88.5 2.95 0.551 296 370 2003 14.0 21.2 5.40 4.40 10.8 16.3 4.13 3.37 35.3 51.9 Mean 38.7 40.4 6.19 2.51 29.9 31.1 4.75 1.92 120 121 Median 18.1 24.9 5.40 1.03 13.9 19.1 4.13 0.78 41.7 61.5 

Buffalo River near Boxley 1999 -- -- -- -- -- -- -- -- 12.9 19.6 

2000 -- -- -- -- -- -- -- -- 4.51 11.1 2001 -- -- -- -- -- -- -- -- 16.9 3.37 2002 -- -- -- -- -- -- -- -- 16.1 36.5 2003 -- -- -- -- -- -- -- -- 1.48 12.8 Mean -- -- -- -- -- -- -- -- 10.4 16.7 Median -- -- -- -- -- -- -- -- 12.9 12.8 

Buffalo River near St. Joe 1999 61.6 106 20.4 0.500 111 177 36.2 1.69 429 795 

2000 17.3 56.3 98.0 11.2 31.9 90.8 140 21.6 121 446 2001 98.4 19.9 3.20 7.24 148 41.3 8.10 15.9 819 122 2002 150 301 11.9 0.550 218 409 25.7 1.86 1,280 2,720 2003 17.3 84.8 9.83 8.59 33.2 138 20.5 16.7 115 657 Mean 68.9 114 28.7 5.62 108 171 46.1 11.6 553 948 Median 61.6 84.8 11.9 7.24 111 138 25.7 15.9 429 657 
Table 5. Seasonal nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment loads and yields for Bear Creek near Silver Hill, the Buffalo River near Box

St. Joe, Arkansas, 1999-2003.--Continued

[Values are loads in pounds per day; N is nitrogen; P is phosphorus; C is carbon; winter defined as December through February; spring defined as March through May; summer fall defined as September through November; values were rounded to three significant figures; --, not calculated]

Dissolved organic carbon as C Suspended sediment 

Site Year Winter Spring Summer Fall Winter Spring Summer Fall

Bear Creek near Silver Hill 1999 1,270 1,860 439 16.1 43,000 59,400 13,500 828

2000 1,120 2,930 1,110 418 32,700 78,400 33,700 14,4002001 5,530 588 112 53.7 142,000 21,300 4,650 2,4102002 8,560 10,800 244 36.1 218,000 278,000 9,120 1,6902003 1,060 1,570 352 302 33,500 50,600 12,800 10,400Mean 3,510 3,540 451 165 93,700 97,600 14,700 5,940Median 1,270 1,860 352 53.7 43,000 59,400 12,800 2,410

Buffalo River near Boxley 1999 -- -- -- -- 14,800 22,100 3,050 47.2

2000 -- -- -- -- 5,180 12,300 9,540 2,7302001 -- -- -- -- 18,800 4,020 1,410 2,8802002 -- -- -- -- 17,800 40,200 2,550 1112003 -- -- -- -- 1,760 14,500 1,240 1,530Mean -- -- -- -- 11,700 18,600 3,560 1,460Median -- -- -- -- 14,800 14,500 2,550 1,530

Buffalo River near St. Joe 1999 13,000 21,800 4,250 132 432,000 788,000 148,000 2,270

2000 3,660 11,300 18,900 2,410 121,000 433,000 811,000 75,5002001 19,400 4,400 760 1,630 787,000 127,000 18,000 45,1002002 29,100 57,200 2,670 146 1,220,000 2,560,000 74,400 2,5502003 3,720 17,200 2,180 1,850 117,000 643,000 63,200 58,400Mean 13,800 22,400 5,750 1,230 535,000 910,000 223,000 36,800Median 13,000 17,200 2,670 1,630 432,000 643,000 74,400 45,100
26 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Annual nutrient, dissolved organic carbon, and suspendedsediment yields computed for Bear Creek were greater than 

yields computed for both of the Buffalo River sites (table 4). 

Bear Creek had a mean annual total ammonia plus organic 

nitrogen (as nitrogen) yield for 1999 to 2003 of 503 pounds per 

year per square mile (lbs/yr/mi2

). The mean annual total ammonia plus organic nitrogen yields at the Buffalo River near St. Joe 

and Buffalo River near Boxley were 280 and 159 lbs/yr/mi2

, 

respectively. The mean annual nitrite plus nitrate (as nitrogen) 

yield for Bear Creek was 413 lbs/yr/mi2, which was approximately twice the mean annual yield at the Buffalo River near St. 

Joe and three times the mean annual yield at the Buffalo River 

near Boxley. The mean annual total nitrogen yield at Bear 

Creek was 929 lbs/yr/mi2

 compared to 614 lbs/yr/mi2 at the 

Buffalo River near St. Joe. Bear Creek had a mean annual total 

phosphorus yield of 139 lbs/yr/mi2

, which was slightly greater 

than the mean annual yield at the Buffalo River near St. Joe (87 

lbs/yr/mi2

) and more than six times the mean annual yield at the 

Buffalo River near Boxley (22 lbs/yr/mi2

). The mean annual 

dissolved organic carbon yield at Bear Creek (4,070 lbs/yr/mi2

) 

was nearly double the mean annual yield for the Buffalo River 

near St. Joe (2,130 lbs/yr/mi2

), and the mean annual suspendedsediment yield at Bear Creek (112,000 lbs/yr/mi2

) also was 

greater than the mean annual yield at the Buffalo River near St. 

Joe (84,300 lbs/yr/mi2). The mean annual suspended-sediment 

yield at Bear Creek was more than four times the mean annual 

yield at the Buffalo River near Boxley.

Annual yields of nutrients for Bear Creek and the two Buffalo River sites for 1999 through 2003 were compared to yields 

for Calf Creek for 2001 through 2002 (Galloway and Green, 

2004), and to yields for 82 sites representing undeveloped 

basins throughout the Nation for 1990 through 1995 (Clark and 

others, 2000). One site that is included in Clark and others 

(2000), North Sylamore Creek near Fifty-Six, Arkansas, 

located in the Ozark Plateaus, also was used for comparison, 

with annual yields recomputed with data for 1990 to 2002. 

Annual yields also were compared to a site representative of a 

developed basin that is affected by both point and non-point 

sources of nutrients, dissolved organic carbon, and suspended 

sediment, the Illinois River south of Siloam Springs, Arkansas 

(Green and Haggard, 2001), with annual yields recomputed 

with data for 1996 through 2002.

Median annual nutrient yields for Bear Creek generally 

were greater than yields for undeveloped basins (including 

North Sylamore Creek), and the Buffalo River near Boxley, but 

lower than values for Calf Creek and the Illinois River (developed basin) (fig. 11). Median annual nitrite plus nitrate, total 

nitrogen, and orthophosphorus yields for Bear Creek and the 

Buffalo River near St. Joe were less than the 75th percentile of 

yields for the undeveloped basins, and the median annual total 

phosphorus yields for both sites were greater than the 75th percentile of yields for the undeveloped basins. The median annual 

nitrite plus nitrate and total nitrogen yields for Bear Creek were 

less than one-thirteenth and one-ninth the yields for the Illinois 

River, respectively. The median annual orthophosphorus and 

total phosphorus yields for Bear Creek were less than one-eighteenth and one-eighth the yields for the Illinois River, respectively.

Flow-Weighted Concentrations

Bear Creek had greater mean annual nutrient, dissolved 

organic carbon, and suspended-sediment flow-weighted concentrations than both the Buffalo River near St. Joe and the Buffalo River near Boxley (table 6). The mean annual total ammonia plus organic nitrogen flow-weighted concentration for Bear 

Creek was 0.46 mg/L as nitrogen, which was 1.6 times the mean 

flow-weighted concentration for Buffalo River near St. Joe and 

nearly five times the flow-weighted concentration for Buffalo 

River near Boxley. The mean annual nitrite plus nitrate flowweighted concentration for Bear Creek was twice the mean 

annual flow-weighted concentration for the Buffalo River near 

St. Joe and more than five times the flow-weighted concentration for the Buffalo River near Boxley. Bear Creek had a mean 

annual total nitrogen concentration that was 1.5 times the mean 

annual flow-weighted concentration for the Buffalo River near 

St. Joe. Although the mean annual dissolved phosphorus flowweighted concentration for Bear Creek was four times the flowweighted concentration for the Buffalo River near St. Joe, the 

mean annual orthophosphorus and total phosphorus flowweighted concentrations were similar between the two sites. 

The mean annual total phosphorus flow-weighted concentration 

for Bear Creek was 13 times the flow-weighted concentration 

for the Buffalo River near Boxley. Bear Creek had a mean 

annual dissolved organic carbon flow-weighted concentration 

of 3.78 mg/L as carbon, which was 1.7 times the mean annual 

flow-weighted concentration at the Buffalo River near St. Joe. 

The mean annual suspended-sediment flow-weighted concentration for Bear Creek was similar to the mean annual concentration at the Buffalo River near St. Joe and seven times the 

mean annual flow-weighted concentration for the Buffalo River 

near Boxley. In general, the Buffalo River near Boxley had the 

least flow-weighted concentration of total phosphorus and suspended sediment probably because land use in the basin 

upstream from the site has a higher percentage of forested land 

than in the Bear Creek Basin and in the basin upstream from the 

Buffalo River near St. Joe, and because fewer samples were collected during high-flow conditions.

Annual flow-weighted concentrations of nutrients at Bear 

Creek and the two Buffalo River sites for 1999 through 2003 

were compared to flow-weighted concentrations at Calf Creek 

for 2001 and 2002 (Galloway and Green, 2004), and to flowweighted concentrations for 82 sites representing undeveloped 

basins throughout the Nation for 1990 through 1995 (Clark and 

others, 2000). One site that is included in Clark and others 

(2000), North Sylamore Creek near Fifty-Six, Arkansas, 

located in the Ozark Plateaus, also was used for comparison, 

with annual flow-weighted concentrations recomputed with 

data for 1990 to 2002. Annual flow-weighted concentrations 

also were compared to a site representative of a developed basin 

that is affected by both point and non-point sources of nutrients, 
Water-Quality Characteristics 27

dissolved organic carbon, and suspended sediment, the Illinois 

River south of Siloam Springs, Arkansas (Green and Haggard, 

2001), with annual flow-weighted concentrations recomputed 

with data for 1996 through 2002.

Median annual flow-weighted concentrations of nutrients 

at Bear Creek generally were greater than flow-weighted concentrations for the two sites on the Buffalo River, North Sylamore Creek, and other sites in undeveloped basins; median annual 

flow-weighted concentrations of nutrients at Bear Creek were 

less than concentrations for the Illinois River (fig. 12). The 

median flow-weighted concentrations for nitrite plus nitrate, 

orthophosphorus, and total phosphorus at Bear Creek were 

greater than the 75th percentile of the flow-weighted concentrations for undeveloped basins. Bear Creek also had the greatest 

median total 

phosphorus flow-weighted concentrations among all of the sites 

with the exception of the Illinois River. Median nitrite plus 

nitrate and total nitrogen flow-weighted concentrations at Bear 

Creek were less than one-fifth and one-third the flow-weighted 

concentrations at the Illinois River, respectively. Median orthophosphorus and total phosphorus flow-weighted concentrations 

at Bear Creek were less than one-seventh and one-third the 

flow-weighted concentrations at the Illinois River, respectively.

Figure 11. Median annual nutrient yields for Bear Creek near Silver Hill, the Buffalo River near Boxley, the Buffalo River near St. Joe, and other

selected basins.
Table 6. Annual nitrogen, phosphorus, dissolved organic carbon, and suspended-sediment flow-weighted concentrations for Bear Creek near Silver Hill, the Buffalo R

and the Buffalo River near St. Joe, Arkansas, 1999-2003.

[Values are in milligrams per liter; N, nitrogen; P, phosphorus; C, carbon; --, not calculated]

Site Year

Total ammonia

plus organic

nitrogen as N

Nitrite plus

nitrate as N

Total nitrogen

as N

Dissolved

phosphorus

as P

Orthophosphorus

as P

Total

phosphorus

as P

Dissolved

organic

carbon as C

S

Bear Creek near Silver Hill 1999 0.36 0.48 0.94 0.04 0.03 0.10 3.02 

2000 0.45 0.43 0.91 0.04 0.03 0.12 3.65 2001 0.59 0.40 0.96 0.05 0.04 0.16 4.76 2002 0.62 0.38 0.97 0.05 0.04 0.17 4.93 2003 0.30 0.47 0.87 0.04 0.03 0.08 2.53 Mean 0.46 0.43 0.93 0.04 0.03 0.13 3.78 Median 0.45 0.43 0.94 0.04 0.03 0.12 3.65 

Buffalo River near Boxley 1999 0.10 0.08 -- -- -- 0.01 -- 

2000 0.10 0.08 -- -- -- 0.01 -- 2001 0.10 0.08 -- -- -- 0.01 -- 2002 0.10 0.08 -- -- -- 0.01 -- 2003 0.10 0.08 -- -- -- 0.01 -- Mean 0.10 0.08 -- -- -- 0.01 -- Median 0.10 0.08 -- -- -- 0.01 -- 

Buffalo River near St. Joe 1999 0.25 0.20 0.54 0.01 0.02 0.07 2.02 

2000 0.29 0.21 0.65 0.01 0.02 0.09 2.24 2001 0.30 0.22 0.67 0.01 0.02 0.10 2.29 2002 0.35 0.24 0.78 0.01 0.02 0.12 2.56 2003 0.22 0.18 0.48 0.01 0.02 0.06 1.81 Mean 0.28 0.21 0.63 0.01 0.02 0.09 2.19 Median 0.29 0.21 0.65 0.01 0.02 0.09 2.24 
 Water-Quality Characteristics 29

Figure 12. Median annual nutrient flow-weighted concentrations for Bear Creek near Silver Hill, the Buffalo River near Boxley, the Buffalo River near 

St. Joe, and other selected basins.
30 Hydrologic and Water-Quality Characteristics for Bear Creek near Silver Hill, Arkansas, and Selected Buffalo River Sites, 

1999-2004

Summary

The purpose of this report is to describe and compare the 

hydrologic and water-quality characteristics of Bear Creek near 

Silver Hill, Arkansas, to two sites on the Buffalo River 

upstream from the confluence of Bear Creek, to a site on Calf 

Creek, a smaller tributary to the Buffalo River, to selected undeveloped sites across the Nation, and to a developed site in 

Arkansas. A better understanding of the hydrology and water 

quality of Bear Creek is of interest to many, including the 

National Park Service, which administers the Buffalo National 

River, to evaluate its effects on the hydrology and water quality 

of the Buffalo River.

The streamflow at Bear Creek near Silver Hill varied seasonally and annually from January 1999 to March 2004. The 

mean annual streamflow for Bear Creek for calendar years 1999 

to 2003 was 86.0 ft3

/s. The highest annual mean streamflow 

occurred in 2002 (158 ft3

/s) and the lowest annual mean streamflow occurred in 1999 (56.4 ft3

/s).The highest streamflows 

occurred in the winter and spring and the lowest streamflows 

occurred in the summer and fall. The streamflow at the Buffalo 

River near Boxley, the Buffalo River near St. Joe, and Calf 

Creek near Silver Hill also varied annually and seasonally. The 

mean annual streamflow for calendar years 1999 to 2003 at the 

Buffalo River near Boxley and Buffalo River near St. Joe were 

102 ft3

/s and 881 ft3/s, respectively. 

Concentrations of nitrogen measured at Bear Creek generally were greater than concentrations measured at the two Buffalo River sites and were similar to concentrations measured at 

Calf Creek. Concentrations of phosphorus measured at Bear 

Creek generally were greater than concentrations measured for 

the two Buffalo River sites and were similar to concentrations 

measured at Calf Creek. Fecal indicator bacteria concentrations 

generally were greater at Bear Creek than concentrations measured at the Buffalo River and similar to concentrations at Calf 

Creek. Concentrations of fecal indicator bacteria were substantially greater at Bear Creek during high-flow conditions than 

during base-flow conditions. Bear Creek had significantly 

greater suspended-sediment concentrations than the Buffalo 

River near Boxley and the Buffalo River near St. Joe, and similar concentrations to Calf Creek. 

Nutrients, dissolved organic carbon, and suspended sediment loads for Bear Creek and two Buffalo River sites varied 

because of differences in land use and contributing drainage 

area for each site. In general, the Buffalo River near St. Joe had 

the greatest annual loads of nutrients, dissolved organic carbon, 

and suspended sediment. The Buffalo River near Boxley had 

less annual nutrient and suspended-sediment loads than Bear 

Creek and the Buffalo River near St. Joe. Greater loads would 

be expected at the Buffalo River near St. Joe because of the 

higher volume of streamflow that occurs at the site. Buffalo 

River near Boxley had lesser annual loads than the other two 

sites probably because of the higher percentage of forested land 

in the basin and a smaller contributing drainage area.

Mean annual nutrient, dissolved organic carbon and suspended-sediment yields computed for Bear Creek were greater 

than yields computed for both of the Buffalo River sites. Bear 

Creek had greater median annual nutrient yields than selected 

undeveloped basins across the Nation and less median annual 

nutrient yields than the Illinois River south of Siloam Springs, 

which is representative of a developed basin.

Bear Creek had greater mean annual flow-weighted nutrient concentrations than the Buffalo River near St. Joe and the 

Buffalo River near Boxley. Bear Creek also had greater median 

flow-weighted nutrient concentrations than selected undeveloped sites across the Nation and less median flow-weighted 

concentrations than the Illinois River south of Siloam Springs 

(developed basin). 

References

Brossett, T. H. and Evans, D.A., 2003, Water Resources Data, 

Arkansas, water year 2002: U.S. Geological Survey WaterData Report AR-02-1, 461 p.

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

concentrations and yields in undeveloped stream basins of 

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Cohn, T.A., 1995, Recent advances in statistical methods for the 

estimation of sediment and nutrient transport in rivers, U.S. 

National Report to the International Union Geodesy and 

Geophysics, 1991-1994: Reviews of Geophysics, Supplement 33, p. 1117-1123.

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References 31

Galloway, J.M. and Green, W.R., 2004, Hydrologic and waterquality characteristics for Calf Creek near Silver Hill, Arkansas and selected Buffalo River sites, 2001-2002: U.S. Geological Survey Scientific Investigations Report 2004-5007, 

29 p.

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concentrations and loads at Illinois River south of Siloam 

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AND SELECTED BUFFALO RIVER SITES, 1999-2004—U.S. Geological Survey Scientific Investigations Report 2004-5244