Watershed Management for Potable Water Supply Assessing the New York City Strategy (2000) / Chapter Skim
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12 Overarching Issues
12 Overarching Issues
Pages 492-514
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From page 492... ...
Nutrients such as phosphorus are addressed in the Clean Water Act and are not a direct public health concern in drinking water. In fact, phosphate is often added to potable water supplies to retard corrosion in distribution networks and household plumbing, thereby reducing lead and copper concentrations.
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From page 493... ...
Third, attention is placed on phosphorus, which has several major impacts on potable water supplies. It can drive algal productivity in surface waters, which is the case in most of the City's water supply reservoirs.
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From page 494... ...
Phytoplankton can release organic taste- and odor-causing substances to surface waters. Algae serve as substrates for bacteria and other organisms that also release organic carbon compounds.
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From page 495... ...
High levels of DOC in water supplies can reduce flexibility in treating water for pathogens by preventing water suppliers from aggressively disinfecting their water with chlorine. In order to manage DOC effectively, the City must determine the origins of DOC in the water supply and evaluate possible differences among those sources on the formation of DBPs and on other processes.
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From page 496... ...
Because removal processes for allochthonous DOC are almost all biological, time is the most important factor for reducing concentrations of these recalcitrant compounds. Traditional urban stormwater and agricultural BMPs are not expected to remove DOC to any significant degree.
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From page 497... ...
. Monitoring data have shown that nonpoint sources contribute significant amounts of soluble phosphorus, comprising about 61 percent of soluble reactive phosphorus between 1992 and 1996 in the Cannonsville watershed (Longabucco and Rafferty, 1998~.
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From page 498... ...
Improvements in OSTDS design, installation of urban stormwater and agricultural BMPs, and performance monitoring of these technologies are fundamental to meeting these goals. Turbidity Phytoplankton growth is a source of turbidity in the water supply reservoirs that is being adequately controlled by the City's efforts to limit phosphorus loading from point and nonpoint inputs.
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From page 499... ...
To promote successful implementation, the New York City Department of Environmental Protection (NYC DEP) should seek the cooperation of the Catskill Watershed Corporation, the Watershed Agricultural Program, the Watershed Forestry Program, or town officials in contacting landowners to gain permission to undertake erosion and sediment control.
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From page 500... ...
NYC DEP should concentrate on measuring the success of nonpoint source BMPs in reducing both particulate and soluble phosphorus. Nonpoint sources are the logical future focus of phosphorus reduction efforts rather than WWTPs, which are adequately addressed by the MOA upgrades.
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From page 501... ...
A substantial financial resource provided by the City under the MOA, the Catskill Fund for the Future, is being used to fund only environmentally sensitive development projects. This $59.7 million dollar fund has the potential to complement the extensive infrastructure upgrades and regulatory actions undertaken in the interest of water quality and to fund income-generating activities that will advance the economic welfare of the region.
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From page 502... ...
The decline in regional real wages occurred even though real wages in the watershed counties are substantially lower than the State average wages for every Standard Industrial Classification Sector (HR&A, 1998a)
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From page 503... ...
Such measures will help to maintain high water quality in the West-of-Hudson reservoirs over the next several years, assuming growth rates do not increase substantially. The committee thinks moderate population growth and a wide range of new economic activities can be accommodated in the watershed without deleterious impacts on water quality as long as development regulations are rigorously implemented and the extensive water quality infrastructure investments now being planned are put in place.
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From page 504... ...
The committee believes that the concept of balancing development restrictions and incentives is a reasonable strategy for New York City and possibly other communities. Because the City committed substantial financial resources to help advance environmentally sensitive development, other regulatory, land acquisition, and water quality investment programs that will contribute significantly to protection of its drinking water supply are moving forward.
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From page 505... ...
Watershed management and treatment process such as disinfection and coagulation/filtration are examples of barriers that comprise the multiple-barrier approach to providing safe drinking water endorsed by EPA, water supply organizations, and this committee. Other barriers include having the highest-quality source water, using the best available treatment technologies, maintaining a clean distribution system, practicing thorough monitoring and accurate data analyses, having well-trained operators, and maintaining operating equipment.
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From page 506... ...
Although it presently complies with all federal and state standards for drinking water quality, a time may come when New York City will want or need to add additional barriers for the protection of its drinking water supply. Direct filtration and alternative disinfection, for which risk reduction can be systematically quantified, are the most probable and well-characterized additional treatment options, given the pilot studies already completed on these processes.
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From page 507... ...
Summary New York City and other signatories of the MOA are commended for bolstering the multiple-barrier approach to water supply protection. Although limitations are noted in this report, the MOA is a template for proactive watershed management that, if diligently implemented over the long term, will improve source water quality.
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From page 510... ...
By contrast, coagulation/filtration or its equivalent, when operated properly, is effective against microbial pathogens, particulates, and the organic carbon precursors of DBPs. Furthermore, additional treatment options can reduce risk by predictable amounts.
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From page 511... ...
, suggesting that filtration could lower the risk of waterborne cryptosporidiosis by a factor of 100. It is clear that if other factors controlling water quality remain the same, treatment beyond disinfection alone can enhance public health protection in an unfiltered water supply.
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From page 512... ...
to prevent existing and potential contaminants from reaching the source reservoirs, (2) to monitor a broad range of water quality and drinking water parameters, (3)
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From page 513... ...
Watershed Protection Techniques 1(3)
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Key Terms
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