In cooperation with the Connecticut Department of Environmental Protection The Thames Science Plan: Suggested Hydrologic Investigations to Support Nutrient-Related Water-Quality Improvements in the Thames River Basin, Connecticut Open-File Report 2005-1208 U.S. Department of the Interior U.S. Geological Survey The Thames Science Plan: Suggested Hydrologic Investigations to Support Nutrient-Related Water-Quality Improvements in the Thames River Basin, Connecticut By Elaine C. Todd Trench In cooperation with the Connecticut Department of Environmental Protection Open-File Report 2005-1208 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior Gale A. Norton, Secretary U.S. Geological Survey Charles G. Groat, Director U.S. Geological Survey, Reston, Virginia: 2005 For sale by U.S. Geological Survey, Information Services Box 25286, Denver Federal Center Denver, CO 80225 For more information about the USGS and its products: Telephone: 1-888-ASK-USGS World Wide Web: http://www.usgs.gov/ Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. iii Contents Purpose, Development, and Organization of the Thames Science Plan. 1 Background . 1 The Importance of Nutrients. 2 Sources of Nutrients in the Thames River Basin . 2 Environmental Setting of the Thames River Basin. 2 Water-Quality Management Issues. 3 Conceptual Model of the Thames River Basin. 9 The Freshwater Ecosystem. 10 Drainage Basins that Receive Point Discharges. 11 Impoundments . 13 Norwich Harbor and the Thames Estuary. 14 Review of the Historical Database for the Thames River Basin . 15 U.S. Geological Survey . 15 Connecticut Department of Environmental Protection . 18 U.S. Army Corps of Engineers. 22 Massachusetts Department of Environmental Protection. 22 Other Sources of Information. 22 Assessment of Information Needs. 24 Ponds and Impoundments . 28 West Thompson Lake. 28 Other Impoundments . 28 Freshwater Streams . 29 Norwich Harbor and the Thames Estuary. 30 Summary of Suggested Investigations to Fulfill Information Needs . 31 Suggested Freshwater Investigations . 34 F1 – Analysis and Interpretation of Information on Nutrient Sources and Water Quality in the Thames River Basin, 1970-2004 . 37 F2 – Evaluation of Surface-Water-Quality Sampling Design for the Thames River Basin. 37 F3 – Spatial (GIS) Analysis of Thames River Basin Information. 37 F4 – Nutrient Concentrations and Loads in the Quinebaug River Basin . 37 F5 – Quinebaug Phosphorus Trends. 37 F6 – Seasonal Phosphorus Trends in the Quinebaug River. 37 F7 – Annual Nutrient Budget for West Thompson Lake. 38 F8 – Daily and Seasonal Nutrient Loads at West Thompson Lake. 38 F9 – Bioavailable Phosphorus in West Thompson Lake Sediment . 38 F10 –Nutrient Enrichment and Algal Productivity in the Quinebaug River Basin . 38 F11 – Algal Growth Bioassay for West Thompson Lake. 38 F12 –Annual and Seasonal Nutrient Loads from Wastewater-Treatment Facilities . 38 F13 –Nutrient Concentrations and Loads in Pristine, Forested Areas. 39 F14 – Assessment of the Contribution of Nutrients from Ground-Water Inflow . 39 F15 – Quantification of Point and Nonpoint Sources of Nutrients in the Quinebaug River Basin . 39 iv F16 – Time-of-Travel Studies on the Quinebaug River. 39 F17 – Streamflow Regulation and Effects on West Thompson Lake . 40 F18 – The Effects of Changes in Phosphorus Loading to West Thompson Lake . 40 F19 – Spatial and Temporal Distribution of Nutrient Enrichment and Phytoplankton Algal Growth in the Quinebaug River Basin. 40 F20 – Streamflow Regulation and Water Quality in the Quinebaug River . 40 F21 – Simulation of Phosphorus and Algal Dynamics on the Main Stem of the Quinebaug River. 40 F22 – Nutrient Trends in the Thames River Basin . 41 F23 – Preliminary Quantification of Nutrient Sources and Loads for the Shetucket River Basin . 41 F24 – Simulation of Nutrient Loads Based on Watershed Characteristics. 41 F25 – Interstate Thames Watershed Model . 41 Suggested Estuarine Investigations . 41 E1 – Assessment and Interpretation of Available Hydrodynamic and Water-Quality Information for Norwich Harbor and the Thames Estuary. 41 E2 – Monitoring to Define Tidal Hydrodynamics in Norwich Harbor. 41 E3 – Monitoring to Define Water-Quality Variability Over a Range of Climatic and Tidal Conditions in Norwich Harbor. 42 E4 – Sources of Nutrients and Organic Loads to Norwich Harbor . 42 E5 – Phytoplankton Community Composition and Dynamics in Freshwater Inflows and Norwich Harbor. 42 E6 – Assessment of Sediment Oxygen Demand . ..