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U.S. GEOLOGICAL SURVEY

Scientific Investigation Report 2004-5125


Nutrient and Sediment Concentrations, Loads, and Trends for Four Nontidal Tributaries in the Chesapeake Bay Watershed, 19972001

By Michael P. Senus, Michael J. Langland, and Douglas L. Moyer

 

Excess nutrient and sediment loads in the Chesapeake Bay can cause unbalanced water-quality conditions that reduce the amount of oxygen and sunlight available to aquatic plants and organisms. Nutrient and sediment loads and trends were analyzed at four nontidal tributaries in the Chesapeake Bay watershed to collect additional data for the ongoing (since 1985) U.S. Geological Survey Chesapeake Bay River Input Monitoring Program. These sites were Chesterville Branch in Maryland, Conodoguinet Creek in Pennsylvania, North Fork Shenandoah River in Virginia, and South Fork Shenandoah River in Virginia. Monthly base-flow and stormflow water-quality samples were collected at each site, with a total of 90–120 samples collected at each site during the study period (1997–2001). These data were used to compute annual and monthly loads for selected nutrient and suspended-sediment constituents using a mass-load estimating model, ESTIMATOR, developed by the U.S. Geological Survey. Each of the four study sites in this report was characterized on the basis of land use and water-quality data. Basins with high percentages of agricultural land use had higher nitrogen and phosphorus loads and yields than basins with higher percentages of forested land and less agricultural land. No relation between land use and suspended-sediment loads and yields was evident. Study results also indicate that suspended-sediment loads were higher in years of high mean annual streamflow at Conodoguinet Creek, North Fork Shenandoah River, and South Fork Shenandoah River. The highest total suspended-sediment loads and yields at Chesterville Branch were caused by Hurricane Floyd in 1999, which was not a year with the highest annual total streamflow. Results of this study indicate that a 5-year period of record is too short a timeframe to characterize factors affecting trends. Moreover, a combination of extreme variability in climate and lack of recent land-use data made characterizing basin nutrient and sediment relations problematic. Although the data and analysis established a baseline of water quality at the four tributaries, additional monitoring and tracking of loads would help identify long-term trends and factors affecting trends.

 

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Contents

Abstract

Introduction

Background

Purpose and scope

Previous studies

Acknowledgments

Description of study sites

Chesterville Branch near Crumpton, Maryland

Conodoguinet Creek near Hogestown, Pennsylvania

North Fork Shenandoah River near Strasburg, Virginia

South Fork Shenandoah River at Front Royal, Virginia

Methods of study

Data collection

Measurement of streamflow

Water-quality samples

Collection technique and equipment

Sample processing and analysis

Quality-assurance program

Data analysis

Estimation of loads

Calculation of trends

Concentrations, loads, and trends at study sites

Concentrations of nutrients and suspended sediment

Chesterville Branch

Conodoguinet Creek

North Fork Shenandoah River

South Fork Shenandoah River

Loads of nutrients and suspended sediment

Chesterville Branch

Conodoguinet Creek

North Fork Shenandoah River

South Fork Shenandoah River

Trends of nutrients and suspended sediment

Chesterville Branch

Conodoguinet Creek

North Fork Shenandoah River

South Fork Shenandoah River

Comparison of study sites

Summary and conclusions

References cited

Appendix A

Appendix B

Figures

13. Maps showing:

1. Location of Chesapeake Bay watershed study area, study site basins, and Chesapeake Bay River Input Monitoring Program site basins

 

2. Location of Chesapeake Bay watershed study area showing land-use percentages of study site basins

 

3. Hydrogeomorphic regions in the Chesapeake Bay watershed

 

45. Photographs showing:

 

4. Stainless-steel weighted-bottle sampler and hand-reel with polyethylene rope

 

5. DH-95 isokinetic sampler with 1-liter Teflon bottle

 

6. Boxplots showing range of concentrations of (A) total nitrogen, (B) total phosphorus, and (C) suspended sediment at study sites

 

710. Graphs showing:

7. Daily mean discharge and observed concentrations for (A) total nitrogen, (B) total phosphorus, and (C) suspended sediment at Chesterville Branch near Crumpton, Maryland, January 1997 through December 2001

 

8. Daily mean discharge and observed concentrations for (A) total nitrogen, (B) total phosphorus, and (C) suspended sediment at Conodoguinet Creek near Hogestown, Pennsylvania, January 1997 through December 2001

 

9. Daily mean discharge and observed concentrations for (A) total nitrogen, (B) total phosphorus, and (C) suspended sediment at North Fork Shenandoah River near Strasburg, Virginia, January 1997 through December 2001

 

10. Daily mean discharge and observed concentrations for (A) total nitrogen, (B) total phosphorus, and (C) suspended sediment at South Fork Shenandoah River at Front Royal, Virginia, January 1997 through December 2001

 

1112: Bar charts showing:

11. Mean annual streamflow at study sites, 19972001

 

12. Calculated yields for (A) total nitrogen, (B) total phosphorus, and (C) suspended sediment at study sites, 19972001

 

1315: Plots showing:

13. Comparison of average annual yields for (A) total nitrogen, (B) total phosphorus, and (C) suspended sediment and percentage of agricultural land use at the study sites and River Input Monitoring Program sites, 19972001

 

14. Comparison of average annual yields for (A) total nitrogen, (B) total phosphorus, and (C) suspended sediment and percentage of forested land use at the study sites and River Input Monitoring Program sites, 19972001

 

15. Comparison of average annual yields for (A) total nitrogen, (B) total phosphorus, and (C) suspended sediment and percentage of developed land use at the study sites and River Input Monitoring Program sites, 19972001

Tables

1. Study site locations and land-use characteristics in the study basins, Chesapeake Bay watershed

 

2. Constituents and field parameters monitored at study sites in the Cheapeake Bay watershed, 19972001

 

3. Summary statistics for selected water-quality constituents monitored at the study sites in the Chesapeake Bay watershed, 19972001  


This report is available as a gif file (Large Print Size) and in Portable Document Format (PDF)(8½ x 11 printed size).

 

View the SIR 2004-5125 report in PDF (10 KB)

 

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For more information about USGS activities in Maryland, Delaware, and the District of Columbia, contact:

 

Director
MD-DE-DC Water Science Center
U.S. Geological Survey
8987 Yellow Brick Road
Baltimore, MD 21237

 

Telephone: (410) 238-4200
Fax: (410) 238-4210

 

or access the USGS Water Resources of Maryland, Delaware, and District of Columbia home page at:  http://md.water.usgs.gov/.



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