AWWA SRC58322

The New York City Water Supply System provides drinking water for 9 million consumers in the city and surrounding areas. Most of this water comes from near-pristine sources in the Catskill and Delaware Systems, but up to 30% is supplied by the Croton System. The 380 square mile Croton Watershed, which first supplied water to New York City in 1842, adjoins the City and consists primarily of residential and natural areas. The New York City Department of Environmental Protection (NYCDEP) is researching current and future risks to Croton water quality and looking for effective and efficient management strategies to ensure source water protection as growth occurs and regulations become increasingly stringent. A team of engineering consultants worked with NYCDEP to develop a GIS-based risk assessment methodology that addresses nutrient, solids, pathogen, and toxics impairments from land-based, septic, and point sources. The methodology combines numerical scores reflecting risk, proximity, and severity for each source category to generate total scores. The assessment results are used to create Basin Reports which summarize current risk levels and possible future trends, while a decision support tool implementing the methodology will be used to evaluate alternative management scenarios. With this tool, NYCDEP will be able to prioritize its watershed monitoring, modeling, protection and restoration efforts as well as provide local stakeholders with technical information for their own watershed programs. The types of watershed strategies likely to be employed are land acquisition, stormwater BMPs, septics management, and smart development. This paper discusses the importance of the Croton Watershed to New York City's water supply and provides an overview of the watershed assessment methodology. A sample Basin Report is presented and explained, and a short demonstration of the GIS-based decision support tool is included. The paper concludes with a summary of expected future directions in the management of the Croton Watershed. Includes tables, figures.