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Executive Summary
Pages 1-22

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From page 1...
... The culmination of years of negotiation between upstate and downstate interests, the MOA commits New York City to a long-term watershed management program that combines land acquisition, new watershed rules and regulations, and financial assistance to watershed communities to promote environmental quality and their local economies. Most important for New York City, the agreement currently satisfies provisions of the Environmental Protection Agency' s (EPA)
From page 2...
... The role of active disease surveillance in watershed management was explored, and a microbial risk assessment was conducted. Finally, the committee considered the potential impact of future changes in federal regulations regarding safe drinking water.
From page 3...
... New York City should lead in efforts to quantify the contribution of watershed management to overall reduction of risk from waterborne pollutants. Watershed management is an essential component of a modern water supply system, but its direct contribution to risk reduction is particularly difficult to quantify.
From page 4...
... ~ I\ .~ $? Atlantic Ocean 40 60 80 Kilometers FIGURE ES-1 New York City water supply system.
From page 5...
... In recent years, however, the need for filtration of surface water supplies has been increasingly emphasized by regulators and public health experts. Since 1989, the SWTR has required every water supplier to filter its surface water sources prior to disinfection unless its source water meets specific water quality criteria and it establishes a watershed management program.
From page 6...
... The SWTR, pursuant to the SDWA, was created to address the health risks of drinking water derived from surface supplies, particularly those risks associated with microbial pathogens. It describes the criteria that must be met by surface water supplies that want to forgo filtration, including the creation of a watershed management program, meeting standards for turbidity and for fecal and total coliforms, providing adequate disinfection, and avoiding any waterborne disease outbreaks.
From page 7...
... These components exist to varying degrees within the MOA and other watershed management programs. CURRENT CONDITIONS IN THE CATSKILL/DELAWARE WATERSHED Common pollutants in the New York City watersheds include microbial, chemical, and physical parameters.
From page 8...
... Performance monitoring is used to evaluate the effectiveness of watershed management practices and policies and to isolate design factors that influence pollutant removal. This type of monitoring in the New York City watersheds is confined to a few specific studies.
From page 9...
... Linking observed disease to drinking water as the route of transmission can only be accomplished with specific epidemiologic studies. New York City has conducted a case-control study for giardiasis and a cross-sectional study of cryptosporidiosis, in which no relationships between drinking water habits and infection were observed, possibly because the study populations were not large
From page 10...
... Although such studies are complex and expensive, they are a rigorous and definitive way to quantify the potential for waterborne disease, and they provide valuable documentation of the safety of the water supply. MICROBIAL RISK ASSESSMENT Active disease surveillance is one analytical tool to estimate potential disease impacts from pathogens in water.
From page 11...
... Risk assessment allows one to ascertain the level of infection implied by a very low level of exposure that would go undetected by active surveillance, thus acting as a complementary source of information about public health. In general, periodic risk estimates should be examined for concordance with prior computed risks and observed illness rates in formulating subsequent water treatment and watershed management decisions.
From page 12...
... The CWC could act as a forum for citizen involvement, provide technical assistance to support local implementation and enforcement, and provide a comprehensive framework for local watershed plans. TOTAL MAXIMUM DAILY LOAD PROGRAM As required by the City' s filtration avoidance determination, TMDLs of the priority pollutant phosphorus have been calculated for all of the New York City water supply reservoirs in two phases (I and II)
From page 13...
... The Phase I goal of 20 ,uglL was not adequately conservative for a drinking water supply, as it is based on ecological and aesthetic considerations. Conservatism in the choice of a phosphorus standard is necessary because data for some of the New York City reservoirs (e.g., Cannonsville)
From page 14...
... Because the ratios do not explicitly take these issues into consideration, they may not afford sufficient protection. There is no evidence that the phosphorus offset pilot program will result in a net reduction in phosphorus loadings to the water supply reservoirs, because the offset ratios were not established with this intent.
From page 15...
... The dual-track approach allows New York City to focus most of its resources on watershed management at this time. Watershed protection reduces source water pollutant concentrations that would be treated by future additional treatment.
From page 16...
... A scientifically based phosphorus load reduction goal that will achieve the desired phosphorus concentration in the water supply reservoirs is needed for the WAP. The purpose of having this load reduction goal is to be able to apportion reductions among different phosphorus outputs from individual subwatersheds and farms.
From page 17...
... development in the New York City watershed region are required to submit a Stormwater Pollution
From page 18...
... Second, information on pollutant removal in buffer zones was used to predict the effectiveness of setbacks. (Buffer zones are natural or managed riparian areas that protect waterbodies from adjacent nonpoint sources of pollution by retaining or transforming pollutants and producing a more favorable environment for aquatic
From page 19...
... Although riparian buffers can ameliorate nonpoint source pollution in some circumstances, they are most effective when used as part of an overall pollution control or conservation plan. WASTEWATER TREATMENT Treatment and disposal of wastewater in the Catskill/Delaware watershed is a major factor in determining the quality of New York City drinking water.
From page 20...
... This recommendation is especially important for the Kensico watershed, because of its critical location in the water supply and because OSTDS serves a large percentage of the population. To ensure that the Continuous Backwash Upflow Dual Sand Filtration units being used at WWTPs represent the best available control technology, these units should be subjected to rigorous long-term monitoring to verify that equivalency with microfiltration is maintained.
From page 21...
... Although its limitations are noted in this report and it is not a guarantee of permanent filtration avoidance, the MOA is a template for watershed management that, if diligently implemented, will maintain and improve source water quality.
From page 22...
... During the course of the study, the committee identified three particularly noteworthy issues that will shape the future of watershed management in water supplies across the country, both filtered and unfiltered: ~ ~ ~ priority setting in watershed management, (2) watershed management and economic development, and (3)


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