NYC Department of Environmental Protection 2017 Watershed Water Quality Annual Report July 2018 Vincent Sapienza, P.E., Commissioner Paul V. Rush, P.E., Deputy Commissioner Bureau of Water Supply Table of Contents Table of Contents ............................................................................................................................. i List of Figures ................................................................................................................................. v List of Tables ................................................................................................................................. ix List of Acronyms ........................................................................................................................... xi Acknowledgements ...................................................................................................................... xiii Executive Summary ...................................................................................................................... xv 1. Introduction ......................................................................................................................... 1 1.1 Water Quality Monitoring of the Watershed ................................................................ 1 1.1.1 Grab Sample Monitoring ......................................................................... 2 1.1.2 Robotic Monitoring (RoboMon) Network .............................................. 3 1.1.3 Early Warning Remote Monitoring (EWRM) ........................................ 5 1.2 Operations in 2017 to Control Turbidity and Fecal Coliforms ..................................... 6 2. Water Quantity .................................................................................................................... 9 2.1 Introduction ................................................................................................................... 9 2.2 2017 Watershed Precipitation ....................................................................................... 9 2.3 2017 Watershed Runoff .............................................................................................. 11 2.4 Use of Rainfall Data in the Design of Stormwater Pollution Prevention Plans .......... 14 2.5 Reservoir Usable Storage Capacity in 2017 ............................................................... 17 3. Water Quality .................................................................................................................... 19 3.1 Monitoring Overview.................................................................................................. 19 3.2 Reservoir Turbidity Patterns in 2017 .......................................................................... 19 3.3 Coliform-Restricted Basin Assessments in 2017 ........................................................ 21 3.3.1 Terminal Basin Assessments ................................................................. 22 3.3.2 Non-Terminal Basin Assessments ........................................................ 22 3.4 Reservoir Total and Fecal Coliform Patterns in 2017 ................................................ 24 3.5 Phosphorus-Restricted Basin Assessments in 2017 .................................................... 27 3.6 Reservoir Total Phosphorus Patterns in 2017 ............................................................. 30 3.7 Reservoir Comparisons to Benchmarks in 2017 ......................................................... 31 3.8 Reservoir Trophic Status in 2017 ............................................................................... 36 3.9 Water Quality in the Major Inflow Streams in 2017 .................................................. 38 3.10 Stream Comparisons to Benchmarks in 2017 ............................................................. 42 i 3.11 Stream Biomonitoring ................................................................................................. 47 3.12 Supplemental Contaminant Monitoring ...................................................................... 53 3.12.1 Volatile (VOC) and Semivolatile Organic (SVOC) Compounds ......... 53 3.12.2 Metals Monitoring ................................................................................. 54 3.13 Special Investigations ................................................................................................. 58 3.13.1 Cannonsville Reservoir Drainage Basin – Kerr’s Creek Manure Pile .. 58 3.13.2 Cannonsville Reservoir Drainage Basin - Dryden Brook Milk Discharge ............................................................................................................... 58 3.13.3 Catskill Aqueduct Leak – Yonkers, New York ..................................... 58 3.13.4 Algal Toxins .......................................................................................... 59 4. Kensico Reservoir ............................................................................................................. 61 4.1 Kensico Reservoir Overview ...................................................................................... 61 4.2 Reservoir Raw Water Quality Compliance ................................................................. 63 4.3 Kensico Watershed Monitoring and Turbidity Curtain Inspections ........................... 68 4.3.1 Kensico Watershed Monitoring ............................................................ 68 4.3.2 Turbidity Curtain Inspection ................................................................. 71 4.4 Waterfowl Management .............................................................................................. 73 4.5 Kensico Research Projects and Special Investigations ............................................... 75 4.5.1 Bryozoans .............................................................................................. 75 4.5.2 Special Investigations within the Watershed ........................................ 79 5. Pathogen Monitoring and Research .................................................................................. 81 5.1 Introduction ................................................................................................................. 81 5.2 Source Water Results .................................................................................................. 82 5.2.1 2017 Source Water Compared to Historical Data ................................. 90 5.2.2 2017 Source Water Compared to Regulatory Levels ............................ 95 5.3 Upstate Reservoir Outflows ........................................................................................ 98 5.4 Watershed Streams and WWTPs .............................................................................. 100 5.5 Hillview Monitoring ................................................................................................. 107 6. Water Quality Modeling ................................................................................................. 111 6.1 Overview ................................................................................................................... 111 6.2 West of Hudson Reservoir Bathymetry .................................................................... 111 6.3 GWLF Streamflow Forecast Automation ................................................................. 113 6.4 Neversink Reservoir Turbidity Model ...................................................................... 117 6.5 Routine Water Quality Forecasts Using Operations Support Tool (OST) ............... 119 ii Table of Contents 6.6 Review of Operations Support Tool (OST) by National Academy of Sciences Expert Panel .......................................................................................................................... 122 6.7 Rondout West Branch Tunnel Shutdown Evaluation ............................................... 123 6.8 Modeling Streamflow Sensitivity to Climate Change using a Stochastic Weather Generator ................................................................................................................... 126 6.9 Projected Changes in Esopus Creek Stream Turbidity under Climate Change Scenarios ................................................................................................................... 128 6.10 Application of the Hydro-Ecologic Model RHESSys to simulate Streamflow, Organic Carbon, and Nitrate in Biscuit Brook ....................................................................... 130 6.11 Application of the General Lake Model/Aquatic Ecodynamics Model to Cannonsville Reservoir ................................................................................................................... 132 6.12 Regionalization Analysis of Observed Precipitation in the West of Hudson Watersheds ................................................................................................................ 134 6.13 Application of SWAT-HS to Evaluate Watershed Protection in the Cannonsville Watershed ................................................................................................................. 136 6.14 A Comparison of SWAT and RHESSys Hydrologic Model Predictions for Town Brook and Biscuit Brook .......................................................................................... 140 6.15 Annual Water Quality Modeling Progress Meeting with Regulators ....................... 143 6.16 Water Quality Modeling: Publications and Presentations