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5 Sources of Pollution in the New York City Watershed
Pages 158-205

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From page 158...
... Discrete, point sources (sewage treatment plants and other sources with discharge permits) and diffuse, nonpoint sources (namely onsite sewage treatment and disposal systems or OSTDS, agriculture, residential and commercial development, forestry, and atmospheric deposition)
From page 159...
... Monitoring studies of wildlife in the New York City watershed found that 6.9 percent of those animals tested were infected with Giardia cysts (NYC DEP, 1998a)
From page 160...
... To elucidate the contribution of wildlife, field research of the kind demonstrated in Box 5-1 is needed in the Catskill region to document the link between wildlife populations and water quality. In the interim, management practices that encourage increases in wildlife populations (e.g., supplemental feeding of deer, posting to prevent hunting, trapping bans on beaver, and some habitat-enhancement techniques)
From page 162...
... Other nonpoint sources include septic tanks, agricultural runoff (as discussed below) , urban stormwater, and groundwater.
From page 163...
... Phosphorus The pollutant in the New York City water supply system that has received the most attention is phosphorus. Phosphorus has been identified as the dominant
From page 164...
... Phosphorus sources in the Catskill, Delaware, and Croton watersheds are many and varied. As with most of the pollutants discussed in this chapter, phosphorus emanates from a variety of point and nonpoint sources such as wastewater treatment plants (WWTPs)
From page 165...
... Organic Carbon Compounds Organic carbon compounds in water supply reservoirs are problematic because some can react with chlorine to form DBPs in the water distribution system. Before describing important sources of organic carbon in the Catskill/ Delaware watershed, it is necessary to define the many parameters used to measure organic carbon concentrations.
From page 166...
... DOC production by phytoplankton certainly increases during the summer relative to allochthonous DOC production, but it is not dominant until hypereutrophic conditions are reached. Thus, on an annual basis, allochthonous DOC will dominate the pool of precursor carbon that is available to react with the disinfectants in the water supply system.
From page 167...
... For the New York City reservoirs, this has usually been accomplished by reducing phosphorus loadings to the reservoirs from both point and nonpoint sources. Sediment Sediment decreases the clarity of water, thereby increasing turbidity and its undesirable effects, such as interference with chlorination.
From page 168...
... , the downhill path of sediment and associated nonpoint source pollutants is inexorable. Changes in the quantity and quality of flow affect the dynamic equilibrium of stream channels.
From page 169...
... NYC DEP monitoring of pesticides has occurred primarily in the distribution system to comply with the Safe Drinking Water Act (SDWA) , in aqueduct entry points (annually)
From page 170...
... It should be noted that none of New York State's top ten facilities for release of toxic compounds is located in either the West-ofHudson or East-of-Hudson watershed regions (Toxics Release Inventory, 1996~. POINT SOURCES OF POLLUTION Domestic Wastewater Treatment Plants Domestic wastewater contains substantial concentrations of pathogenic microorganisms and must be discharged in an area that will ensure removal of pathogens before the effluent reaches groundwater (Veneman,1996~.
From page 171...
... As part of the Watershed Rules and Regulations in the MOA, all sewage treatment plants in the watershed are being upgraded to meet new performance criteria and effluent standards, with upgrades scheduled for completion by 2002 (EPA, 1997~. The most significant of these requirements for WWTPs that discharge to surface waterbodies are the following:
From page 172...
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From page 173...
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From page 176...
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From page 177...
... These residuals must be properly managed to avoid creating a secondary source of contaminants. Though sludge treatment practices vary throughout the watershed, most solid waste generated by WWTPs is eventually buried in landfills within the watershed region or is moved outside the watershed boundaries (Warne, 1998a)
From page 178...
... Thus, industrial point sources cannot be ignored when determining the overall contribution of point sources to pollutant loadings in the water supply reservoirs. NONPOINT SOURCES OF POLLUTION Over the last quarter century, water quality across the country has improved dramatically, primarily as a result of technologies that have greatly reduced pollution from point sources.
From page 179...
... Dairy Cooling water Walton Town Garage Discharge from an Dairyvest at Fraser (Ultra Dairy/DMV) Mallincraft/Grahm Labs Audio-Sears, Inc.
From page 180...
... The high productivity gained in this way also leads to the potential for nonpoint source pollution. In general, as agriculture is practiced in most parts of the United States today, row crops are treated with fertilizers and pesticides and have the potential for contaminating surface waters with nutrients, pesticides, and sediment.
From page 181...
... Urban Stormwater A second important class of activities that produce nonpoint source pollution are classified as "urban." This term encompasses a wide variety of commercial, residential, and industrial activities such as road building, construction of housing, and the creation of golf courses, among other things. There are discrepancies regarding the amount of land in the Catskill/Delaware watershed that is urban.
From page 182...
... Some common pollutants found in urban stormwater runoff are profiled in Table 5-6. Although variable from storm to storm, in general the concentrations of pollutants in urban stormwater can be characterized by an event mean concentration (EMC)
From page 183...
... . In fact, Cryptosporidium was detected in urban watersheds more frequently than in agricultural watersheds and in effluent from sewage treatment plants.
From page 184...
... Reducing the density and biomass of forest cover increases rainfall reaching the soil surface, snowmelt rate in openings, and soil water content in the root zone. All three changes combine to increase water yield.
From page 185...
... As with other nonpoint sources of pollution, measuring the impact of these systems on nearby water quality can be difficult. Performance monitoring of OSTDS effluent in the Catskill/Delaware watershed has not occurred on a regular basis and has only recently become a goal of NYC DEP's septic siting study (see Chapter 11~.
From page 186...
... Properly sited and maintained septic tanks and drainfields remove approximately 80 percent of the BOD and virtually all of the total suspended solids. Removing pathogens from OSTDS effluent before it reaches groundwater is important because various studies have shown that bacteria and especially viruses can travel long distances (15-60 m)
From page 187...
... are classified as "other" systems and are regulated by NYS DOH. Regardless of the classification, failing OSTDS must be detected and repaired rapidly through a vigorous enforcement effort if contaminants are to be prevented from degrading surface water quality.
From page 188...
... Deposition of nitrate and ammonia are important contributions to overall watershed nitrogen budgets in forested watersheds, but are relatively insignificant in agricultural settings where nitrogen fertilizers are often used. Total nitrogen modeling and load allocation in the New York City watershed region has not been performed because the reservoirs have been shown to be primarily phosphorus-limited and because nitrogen water quality standards have not been exceeded.
From page 189...
... Water quality in the water supply reservoirs has a direct impact on aquatic ecosystems and habitats, particularly during eutrophication events. Although few epidemiological studies have conclusively linked waterborne DBPs to human
From page 190...
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From page 191...
... 191 so o o .~ ._ o a' I'd 3 u V]
From page 192...
... Reservoir Water Quality Direct human access to the New York City water supply reservoirs is limited to recreational fishing from row boats, shores, or bridges. However, human activities within the drainage basins have significantly influenced reservoir water quality.
From page 193...
... Water diversions from the Schoharie Reservoir to the upper Esopus Creek via the Shandaken Tunnel also may contribute to sediment transport. Finally, accidental spills of hazardous or other materials in the watershed can have acute, short-term effects on water quality in the water supply reservoirs.
From page 194...
... Vigilance is most necessary during winter, when low temperatures reduce the effectiveness of chlorine. New York City drinking water is currently meeting CT requirements.
From page 195...
... 2 during January 1997. Source: NYC DEP Compliance Reports.
From page 196...
... The ultimate purpose of watershed management is to protect drinking water quality and public health by reducing the amount of contaminants entering the water source. Thus, the filtration avoidance criteria of the SWTR mandate no waterborne disease outbreaks shall occur among the population served by an unfiltered water supply.
From page 197...
... Because bypassing is not an ideal solution given the operational and water quality benefits Kensico provides, in 1991 the City began a study to identify and eliminate the cause of seasonal coliform increases at Kensico Reservoir. Field investigations and limnological sampling showed that an increase in waterfowl populations coincided both temporally and spatially with increases of fecal coliform bacteria in the reservoir.
From page 198...
... Disinfectants/Disinfection By-Products Rule Although the D/DBP Rule will not be promulgated until 2002, it is worthwhile to evaluate this regulation to determine whether the New York City water supply system would be in compliance based on current conditions. Bromate.
From page 199...
... Unfortunately, bromide concentrations were not measured as part of these studies. If ozone is eventually used and bromide is detected in the water supply, bromate may become a pollutant of concern in the New York City drinking water system.
From page 200...
... Some actual measures of reservoir water quality indicate a growing problem with the eutrophic health of the New York City water supply reservoirs (Table 5-9~. All are classified as either mesotrophic or eutrophic, and some have variably high concentrations of phosphorus, chlorophyll a, and turbidity, particularly after large storm events and during certain seasons.
From page 201...
... 1986. Septic Tank System Effects on Ground Water Quality.
From page 202...
... 1990. Microbiological quality of source waters for water supply.
From page 203...
... 1993b. Implications of Phosphorus Loading for Water Quality in NYC Reservoirs.
From page 204...
... 1996. New York State Water Quality 1996.
From page 205...
... 1972. Decomposition of dissolved organic carbon and nitrogen compounds from leaves in an experimental hardwater stream.


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