Table of Contents Table of Contents Table of Contents.................................................................................................................. i List of Tables ........................................................................................................................ v List of Figures....................................................................................................................... vii Acknowledgements............................................................................................................... xi Errata Sheet Issued May 4, 2011 .......................................................................................... xiii 1. Introduction........................................................................................................................ 1 1.1 What is the purpose and scope of this report? ......................................................... 1 1.2 What constitutes the New York City water supply system? ................................... 1 1.3 What are the objectives of water quality monitoring and how are the sampling programs organized? ........................................................................... 3 1.4 What types of monitoring networks are used to provide coverage of such a large watershed? .................................................................................................. 5 1.5 How do the different monitoring efforts complement each other? .......................... 9 1.6 How many water samples did DEP collect in 2009 to monitor the water quality of reservoirs, streams, and aqueducts throughout the upstate watershed? ........................................................................................................... 9 1.7 How has water quality information been used to guide Health and Safety procedures? .............................................................................................. 10 1.8 What enhancements were made to DEP’s monitoring capabilities in 2009? .......... 11 2. Water Quantity................................................................................................................... 13 2.1 What is NYC’s source of drinking water? ............................................................... 13 2.2 How much precipitation fell in the watershed in 2009? ......................................... 13 2.3 What improvements were made to DEP’s meteorological data network in 2009, and how were the data used? .................................................................... 15 2.4 How much runoff occurred in 2009? ....................................................................... 16 2.5 What was the storage history of the reservoir system in 2009? ............................... 19 2.6 What rainfall data are necessary in the design of Stormwater Pollution Prevention Plans? ................................................................................................ 20 2.7 How is the flow of water to the City maintained when an aqueduct must be shut down for maintenance or repair? ............................................................ 24 3. Water Quality..................................................................................................................... 27 3.1 How did DEP ensure the delivery of the highest quality water from upstate reservoirs in 2009? .................................................................................. 27 3.2 How did the 2009 water quality of NYC’s source waters compare with SWTR standards for fecal coliforms and turbidity? .......................................... 28 3.3 Why did some water consumers experience a “metallic taste” of their drinking water in October 2009 and how did DEP control it? ........................... 31 3.4 What was the water quality in the major inflow streams of NYC’s reservoirs in 2009? ............................................................................................. 32 3.5 What factors contributed to the turbidity patterns observed in the reservoirs in 2009? ............................................................................................. 35 3.6 How were the total phosphorus concentrations in the reservoirs affected by precipitation and runoff in 2009? .................................................................. 37 i 3.7 Which basins were phosphorus-restricted in 2009? ................................................. 39 3.8 What was the trophic status of each of the City’s 19 reservoirs and why is this important? ................................................................................................... 41 3.9 What were the total and fecal coliform levels in NYC’s reservoirs? ...................... 43 3.10 Which basins were coliform-restricted in 2009? ................................................... 47 3.11 How did reservoir water conductivity in 2009 compare to previous years? .......... 49 3.12 How did water quality status in terminal reservoirs compare with regulatory benchmarks in 2009? ........................................................................ 51 3.13 Has DEP monitoring of watershed streams revealed any changes to the macroinvertebrate community? .......................................................................... 57 3.14 What can sampling a stream’s macroinvertebrate community tell us about the effectiveness of wastewater treatment plant upgrades? ................................ 63 3.15 What are disinfection by-products, and did organic concentrations in source waters allow DEP to meet compliance standards in the distribution system in 2009? ............................................................................................................... 65 3.16 How does DEP protect the water quality of the Catskill Aqueduct at Kensico Reservoir from stormwater impacts? .................................................... 66 3.17 Did the first year of data for the Cannonsville Recreational Boating Pilot study show any significant water quality impacts? ............................................. 67 3.18 What was the status of compliance with applicable benchmarks for NYC’s streams in 2009? ................................................................................................ 67 3.19 What were the water quality trends in NYC’s reservoirs as of 2009? ................... 69 4. Pathogens ........................................................................................................................... 79 4.1 How many samples did DEP collect for Cryptosporidium, Giardia, and human enteric viruses in 2009, and what were their occurrences and concentrations in the source waters? ................................................................... 79 4.2 How did protozoan concentrations compare with past regulatory levels? .............. 83 4.3 How do 2009 source water concentrations compare to historical data? .................. 84 4.4 What concentrations of Cryptosporidium and Giardia were found at the various NYC watersheds in 2009? ...................................................................... 89 4.5 What levels of protozoa and human enteric viruses were found in wastewater treatment plant effluents in 2009? .................................................... 98 4.6 What concentrations of Cryptosporidium and Giardia were found at the effluents in various NYC reservoirs in 2009? ..................................................... 100 5. Watershed Management..................................................................................................... 105 5.1 What watershed management programs are required for filtration avoidance and how do they protect the water supply? ....................................... 105 5.2 How can watershed management improve water quality? ...................................... 108 5.3 What are DEP’s watershed management efforts in the Catskill/Delaware System? ............................................................................................................... 109 5.4 How has DEP tracked water quality improvements in the Catskill/Delaware System? ............................................................................................................... 112 5.5 What are the watershed management efforts in the Croton System? ...................... 112 5.6 How does DEP avoid water quality impacts which can occur from the presence of waterbirds (Canada geese, gulls, cormorants, and other waterfowl)? ......................................................................................................... 114 ii Table of Contents 5.7 Why is DEP’s Forest Science Program developing forest growth models? ............ 116 5.8 How does DEP address threats to the water supply posed by invasive species? ..... 117 5.9 What does DEP do to protect the water supply from Zebra mussels? ..................... 119 5.10 How do environmental project reviews help protect water quality, and how many were conducted in 2009? ................................................................... 121 5.11 What was the status of WWTP TP loads in the watershed in 2009? .................... 121 5.12 What “Special Investigations” were conducted in 2009? ..................................... 122 6. Model Development and Application................................................................................ 125 6.1 Why are models important and how are they used by DEP? ................................... 125 6.2 What can models tell us about the effects of 2009’s