Prepared in cooperation with the Village of East Hampton Assessment of Water Quality and Fecal Contamination Sources at Hook Pond, East Hampton, New York Scientific Investigations Report 2020–5071 U.S. Department of the Interior U.S. Geological Survey Cover. Front: Hook Pond, viewed looking south from a boat during a sampling trip; photograph by Shawn Fisher, U.S. Geological Survey. Back, bottom left: Waterfowl gathered north of Davids Lane along Hook Pond Dreen (locally known as the duck pond); photograph by Tristen Tagliaferri, U.S. Geological Survey. Back, right: A culvert at Fithian Lane where stormwater from New York State Route 27 enters and Hook Pond Dreen passes through; photograph by Shawn Fisher, U.S. Geological Survey. Assessment of Water Quality and Fecal Contamination Sources at Hook Pond, East Hampton, New York By Shawn C. Fisher, Brendan A. McCarthy, Christopher M. Kephart, and Dale W. Griffin Prepared in cooperation with the Village of East Hampton Scientific Investigations Report 2020–5071 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: 2020 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: Fisher, S.C., McCarthy, B.A., Kephart, C.M., and Griffin, D.W., 2020, Assessment of water quality and fecal contamination sources at Hook Pond, East Hampton, New York: U.S. Geological Survey Scientific Investigations Report 2020–5071, 58 p., https://doi.org/ 10.3133/ sir20205071. Associated data for this publication: U.S. Geological Survey, 2020, USGS water data for the Nation: U.S. Geological Survey National Water Information System database, https://doi.org/10.5066/F7P55KJN. ISSN 2328-0328 (online) iii Acknowledgments The project team would like to thank the following cooperators and stakeholders for provid- ing support that enhanced the results and interpretation of the data collected for this study beyond the proposed assessment. Rebecca Molinaro Hansen and Bill Hajek of the Village of East Hampton provided background and technical information about the storm sewer network and Hook Pond. Kenneth Koch and John Genovesi of the Maidstone Club provided access to the property and assistance with installing the monitoring station at the golf cart bridge. Joette Pavelka, Beth Essex, and April DeVoe at the Suffolk County Department of Health Services Public and Environmental Health Laboratory analyzed samples for fecal indicator bacteria. The project team would also like to thank William Capurso, Michael Noll, and Anthony Chu; Andy Lange; and Banu Bayraktar, all with the U.S. Geological Survey, who assisted in estab- lishing and leveling the continuous monitoring site, streamgaging, and geographic information system (GIS) mapping, respectively. v Contents Acknowledgments ........................................................................................................................................iii Executive Summary .......................................................................................................................................1 Background............................................................................................................................................1 Nutrients .................................................................................................................................................1 Fecal Contamination .............................................................................................................................2 Physicochemical Monitoring and Decision Support ......................................................................2 Introduction.....................................................................................................................................................3 Methods.........................................................................................................................................................10 Site Selection and Access ................................................................................................................10 Field Methods ......................................................................................................................................10 Continuous Water-Quality Monitoring....................................................................................10 Depth Profiles .............................................................................................................................12 Water-Quality and Microbiological Sample Collection �������������������������������������������������������12 Stream Discharge Measurements ..........................................................................................13 Laboratory Methods ...........................................................................................................................13 Nutrient Analysis........................................................................................................................13 Wastewater-Indicator Analysis...............................................................................................13 Nitrogen Isotope Analysis ........................................................................................................14 Microbiological Analyses .........................................................................................................14 Quality Assurance, Ancillary Data, and Interpretation ................................................................15 Water Quality of Hook Pond .......................................................................................................................15 Summary of Continuous Water-Quality Data .................................................................................16 Spatiotemporal Assessment of Physicochemical Constituents in the Hook Pond Watershed ..............................................................................................................................16 Spatiotemporal Assessment of Nutrients and Wastewater-Indicator Compounds in the Hook Pond Watershed ...................................................................................................21 Groundwater Quality Adjacent to Hook Pond ................................................................................28 Sources of Fecal Contamination to Hook Pond ......................................................................................32 Synthesis of Results ....................................................................................................................................32 Contributions of Hook Pond Watershed ..........................................................................................32 Current Hydrologic Conditions of Hook Pond ................................................................................36 Microbial Source Tracking ................................................................................................................37 A Baseline for Future Research .......................................................................................................38 Summary........................................................................................................................................................39 References Cited..........................................................................................................................................40 Appendix 1. Expanded Description of Analytical Methods ...............................................................45 Appendix 2. Surface-Water Clarity Plot and Groundwater Constituents ........................................50 vi Figures 1. Map showing location of the Hook Pond study area, as well as Georgica Pond, East Hampton Airport, the National Oceanic and Atmospheric Administration (NOAA) Montauk tide gage, and two U.S. Geological Survey groundwater observation wells ..........................................................................................................................4 2. Map showing location of Town Pond, Hook Pond Dreen, and Maidstone Club in East Hampton, New York .............................................................................................................5 3. Photographs showing Hook Pond at the spillway that drains water to the Atlantic Ocean under adjacent sand dunes; stone culvert at Fithian Lane where stormwater from New York State Route 27 is discharged and Hook Pond Dreen passes through; and Hook Pond Dreen at area of concentrated waterfowl, locally known as the duck pond, East Hampton, New York ...................................................6 4. Maps of Hook Pond and Hook Pond Dreen sites in East Hampton, New York, where surface-water and groundwater