Prepared in cooperation with the Washington, D.C., Department of Energy & Environment Sediment and Chemical Contaminant Loads in Tributaries to the Anacostia River, Washington, District of Columbia, 2016–17 Scientific Investigations Report 2019–5092 U.S. Department of the Interior U.S. Geological Survey Cover. Low-flow (upper left, June 2017) and flood (lower right, March 2017) conditions at U.S. Geological Survey station 01651730, Beaverdam Creek near Cheverly, Maryland. Photographs by T.P. Wilson, U.S. Geological Survey. Sediment and Chemical Contaminant Loads in Tributaries to the Anacostia River, Washington, District of Columbia, 2016–17 By Timothy P. Wilson Prepared in cooperation with the Washington, D.C., Department of Energy & Environment Scientific Investigations Report 2019–5092 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior DAVID BERNHARDT, Secretary U.S. Geological Survey James F. Reilly II, Director U.S. Geological Survey, Reston, Virginia: 2019 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Wilson, T.P., 2019, Sediment and chemical contaminant loads in tributaries to the Anacostia River, Washington, District of Columbia, 2016–17: U.S. Geological Survey Scientific Investigations Report 2019–5092, 146 p., https://doi.org/10.3133/sir20195092. Associated data for this publication: Wilson, T.P., 2019, Discharge and sediment data for selected tributaries to the Anacostia River, Washington, District of Columbia, 2003–18: U.S. Geological Survey data release, https://doi.org/10.5066/P9RUZSMV. ISSN 2328-0328 (online) iii Acknowledgments The author thanks Dev Murali of the Washington, D.C., Department of Energy & Environment for help in planning and gaining access to sampling sites. The assistance of U.S. Geological Survey employees Charles Walker, Brenda Majedi, Brian Banks, Shannon Jackson, and Jeffrey Kvech in planning, aiding in fieldwork, and developing gaging and sampling stations is gratefully acknowledged. iv Contents Acknowledgments ........................................................................................................................................iii Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................2 Purpose and Scope ..............................................................................................................................4 Study Area.......................................................................................................................................................4 Description of Watersheds .................................................................................................................4 Methods.........................................................................................................................................................19 Collection of Stormflow Samples ....................................................................................................19 Large-Volume Sample Processing ...................................................................................................21 Sampling Methods for Low-Flow Conditions .................................................................................22 Bed-Sediment Sampling ....................................................................................................................22 Sampling for Suspended Sediment and Particulate Organic Carbon ........................................22 Chemical Analysis of Sediment ........................................................................................................23 Chemical Results..........................................................................................................................................26 Quality-Assurance Results ................................................................................................................26 Sediment Toxicity ................................................................................................................................27 Sediment-Bound Chemical Concentrations ...................................................................................27 Sediment and Chemical Loads ..................................................................................................................39 General Load Calculations ................................................................................................................39 Discharge in Gaged Tributaries ........................................................................................................41 Discharge in Ungaged Tributaries ..................................................................................................43 Estimating Suspended-Sediment Concentrations from Measurements of Continuous Turbidity .........................................................................................................45 Sediment Loads in Gaged Tributaries .....................................................................................54 Sediment Loads in Ungaged Tributaries ................................................................................54 Concentrations of Sediment-Bound Contaminants ......................................................................54 Representativeness of Samples ..............................................................................................58 Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons in Suspended Sediment and Bed Sediment ...............................................................................................59 Loads of Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons .........................79 Loads of Polychlorinated Biphenyls and Polyaromatic Hydrocarbons in Ungaged Tributaries ................................................................................................79 Comparison of Loads during Storms and Low Flow ......................................................................79 Pesticide Concentrations and Loads ...............................................................................................81 Metal Concentrations and Loads .....................................................................................................85 Comparison of Loads of Contaminants of Concern with Total Maximum Daily Load Allocations ....................................................................................................................88 Summary........................................................................................................................................................91 References Cited..........................................................................................................................................92 v Appendix 1. Summary of stream discharge, precipitation, and sediment and contaminant loadings for the individual storms sampled in tributaries to the Anacostia River, 2017 ........................................................................................................................................95 Appendix 2. Summary of polychlorinated biphenyl, polycyclic aromatic hydrocarbon, pesticide, and metal concentrations in blank samples and suspended and bed sediment in tributaries to the Anacostia River, 2017 ..............................................................111 Appendix 3. Datasets used to model suspended sediment in tributaries to the Anacostia River, 2017 ......................................................................................................................................127 Figures 1. Maps showing the Anacostia River watershed sampling locations and subwatersheds: A, Anacostia River, B, Beaverdam Creek, C, Watts Branch, D, Hickey Run, E, Nash Run, F, Pope Branch, G, unnamed stream at Fort DuPont, and H, unnamed stream at Fort Stanton ...................................................................................8 2. Graphs showing stage, turbidity, and precipitation in A, Northeast Branch, B, Northwest Branch, C, Beaverdam Creek, D, Watts Branch, and E, Hickey Run during a storm from March 30 through April 2, 2017 .............................................................17 3. Diagram showing configuration of sampling equipment used to collect large-volume and discrete samples .................................................................................................................20 4. Graph showing stage and water velocity in Beaverdam Creek, March 15–April 1, 2017 ...............................................................................................................42