Skip Links

USGS - science for a changing world

Scientific Investigations Report 2010–5252

Prepared in cooperation with Spartanburg Water, Spartanburg, South Carolina

Concentrations, Loads, and Yields of Nutrients and Suspended Sediment in the South Pacolet, North Pacolet, and Pacolet Rivers, Northern South Carolina and Southwestern North Carolina, October 2005 to September 2009

By Celeste A. Journey, Andral W. Caldwell, Toby D. Feaster, Matthew D. Petkewich, and Paul M. Bradley

Thumbnail image of report cover

ABSTRACT

The U.S. Geological Survey, in cooperation with Spartanburg Water, evaluated the concentrations, loads, and yields of suspended sediment, dissolved ammonia, dissolved nitrate plus nitrite, total organic nitrogen, total nitrogen, dissolved orthophosphate, dissolved phosphorus, and total phosphorus at sites in the South Pacolet, North Pacolet, and Pacolet Rivers in northern South Carolina and southwestern North Carolina from October 1, 2005, to September 30, 2009 (water years 2006 to 2009). Nutrient and sediment loads and yields also were computed for the intervening subbasin of the Pacolet River not represented by the South and North Pacolet River Basins.

Except for a few outliers, the majority of the measurements of total nitrogen concentrations were well below the U.S. Environmental Protection Agency recommended guideline of 0.69 milligram per liter for streams and rivers in the nutrient ecoregion IX, which includes the study area within the Pacolet River Basin. Dissolved orthophosphate, dissolved phosphorus, and total phosphorus concentrations were significantly lower at the South Pacolet River site compared to the North Pacolet and Pacolet River sites. About 90 percent of the total phosphorus concentrations at the South Pacolet River site were below the U.S. Environmental Protection Agency recommended guideline of 0.37 milligram per liter, and more than 75 percent of the total phosphorus concentrations at the North Pacolet and Pacolet River sites were above that guideline.

At all sites, minimum annual nutrient loads for the estimation period were observed during water year 2008 when severe drought conditions were present. An estimated mean annual total nitrogen load of 37,770 kilograms per year and yield of 2.63 kilograms per hectare per year were determined for the South Pacolet River site for the estimation period. The North Pacolet River site had a mean annual total nitrogen load of 65,890 kilograms per year and yield of 2.19 kilograms per hectare per year. The Pacolet River had a mean annual total nitrogen load of 99,780 kilograms per year and yield of 1.82 kilograms per hectare per year. Mean annual total phosphorus loads of 2,576; 9,404; and 11,710 kilograms per year and yields of 0.180, 0.313, and 0.213 kilograms per hectare per year were estimated at the South Pacolet, North Pacolet, and Pacolet River sites, respectively. Annually, the intervening subbasin of the Pacolet River contributed negligible amounts of total nitrogen and total phosphorus loads, and large losses of dissolved nitrate plus nitrite and orthophosphate loads were determined for the subbasin. Biological (algal) uptake in the two reservoirs in this intervening area was considered the likely explanation for the loss of these constituents.

Estimated mean annual suspended-sediment loads were 21,190,000; 9,895,000; and 6,547,000 kilograms per year at the South Pacolet, North Pacolet, and Pacolet River sites, respectively. In the intervening Pacolet River subbasin, computed annual suspended-sediment loads were consistently negative, indicating large percentage losses in annual suspended-sediment load. Sedimentation processes in the two reservoirs are the most likely explanations for these apparent losses.

At all sites, the winter season tended to have the highest estimated seasonal dissolved orthophosphate and dissolved nitrate plus nitrite fluxes, and the summer and fall seasons tended to have the lowest fluxes. The reverse pattern, however, was observed in the intervening drainage area in the Pacolet River where the lowest fluxes of dissolved orthophosphate and nitrate plus nitrite occurred during the winter and spring seasons and the highest occurred during the summer and fall seasons.

Synoptic samples were collected during a high-flow event in August 2009 at eight sites that represented shoreline and minor tributary drainages. The South Pacolet River site was identified as contributing greater than 80 percent of the cumulative nutrient and sediment load to the downstream reservoirs for that event. This finding implies that the minor shoreline drainages and tributaries near Lake Bowen and Reservoir #1 were minor contributors to the overall nutrient load into these reservoirs when compared to the South Pacolet River site.

First posted February 15, 2011

For additional information contact:
Director
USGS South Carolina Water Science Center
Stephenson Center, Suite 129
720 Gracern Road
Columbia, SC 29210–7651
phone: 803–750–6100 http://sc.water.usgs.gov/

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.


Suggested citation:

Journey, C.A., Caldwell, A.W., Feaster, T.D., Petkewich, M.D., and Bradley, P.M., 2011, Concentrations, loads, and yields of nutrients and suspended sediment in the South Pacolet, North Pacolet, and Pacolet Rivers, northern South Carolina and southwestern North Carolina, October 2005 to September 2009: U.S. Geological Survey Scientific Investigations Report 2010–5252, 79 p.



Contents

Acknowledgments

Abstract

Introduction

Purpose and Scope

Previous Investigations

Approach and Methods

Streamflow Data Collection

Water-Quality Data Collection

Data Analysis

Quality Assurance

Description of the Study Area

Climate

Flow Characteristics

Land Use

Nutrient and Suspended-Sediment Concentrations, Loads, and Yields

Nutrient and Sediment Concentrations

Annual and Seasonal Nutrient and Sediment Loads and Yields

Instantaneous Loads and Yields at Synoptic Sites

Summary

Selected References

Appendix 1. Summary of selected water-quality data collected from September 2007 to August 2009, Spartanburg County, South Carolina, at the (1-A) South Pacolet River at streamgaging station 02154790, (1-B) North Pacolet River at streamgaging station 02154500, and (1-C) Pacolet River at streamgaging station 02155500

Appendix 2. Ancillary data of streamflow, land use, and water quality

Appendix 3. Selected water-quality data for eight synoptic sites near Lake William C. Bowen and Municipal Reservoir #1 within the Pacolet River Basin and at the South Pacolet River at streamgaging station 02154790, Spartanburg County, South Carolina, November 2008 and August 2009

Appendix 4. S-LOADEST output of estimated annual and seasonal flux and loads and associated variance, 95 percent confidence limits, and standard error of prediction for selected constituents in the South Pacolet River at streamgaging station 02154790, North Pacolet River at streamgaging station 02145000, Pacolet River at streamgaging station 02155500, and computed loads for the intervening drainage area between PAC site upstream to the NPAC and SPAC sites, Spartanburg County, South Carolina, water years 2006–2009


Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://pubsdata.usgs.gov/pubs/sir/2010/5252/index.html
Page Contact Information: USGS Publications Team
Page Last Modified: Thursday, 10-Jan-2013 19:21:53 EST