Making
Watershed
. The size of the watershed is suggested by the scale of this water tunnel, through which daily pass billions of gallons of water to New York City © 2000 American Chemical.Society
Management Work New York City's watershed management strategy is unprecedented in its scope, scale, and cost. LAURA J. EHLERS, MAX J. PFEFFER,
AND CHARLES R. O'MELIA • • ! • ew York City obtains its drinking water from • f t I the upstate Catskili, Delaware, and Croton I ft I watersheds. Taken together, they occupy an I ftl area of 1970 square miles, contain 600 bilI ftl lion gallons of usable water storage, and each day provide up to 2 billion gallons of water (Figure 1). The combined system serves 9 million people in the New York City area. It is the second largest service area of a single water supplier in the United States. The water taken from these upstate systems has been delivered to consumers without first being filtered—only disinfection by chlorination has been used, because historically, water has met drinking water standards. In recent years, however, public health experts have been advocating filtration of sur-
face water supplies to control the protozoa Giardia and Cryptosporidium, which are resistant to chlorine disinfection. This concern has been translated by EPA's 1986 Surface Water Treatment Rule (SWTR) into strict guidelines for treatment of surface water supplies. According to the SWTR, certain criteria must be met in order to forgo filtration, including the creation of a watershed management program. In accordance with this regulation, New York City is preparing to filter water from the more heavily developed Croton watershed. However, because the city has satisfied regulatory criteria for water quality, EPA has granted it a waiver from having to filter water drawn from the combined Catskill/Delaware system, which NOVEMBER 1 2000 ENVIRONMETAL SCIENCE & TECHNOLOGY / NEWS 465
FIGURE 1
Supplying the city's drinking water Each day, the Catskill, Delaware, and Croton watersheds, encompassing 1970 square miles and containing 600 billion gallons of usable storage, provide as much as 2 billion gallons of water to New York City. The combined system serves 9 million people in the New York City area, the second largest service area of a single water supplier in the United States.
Source: Adapted from New York City Department of Environmental Protection.
constitutes 90% of the water supply. To maintain its waiver, New York City has embarked on a strategy of watershed management that is unprecedented in scope, scale, and cost. Balancing New York City's interest in protecting the watershed for a high-quality water supply against the economic, recreational, and other interests of watershed residents is challenging. Private ownership a c c o u n t s for 73% of t h e c o m b i n e d Catskill/ Delaware watershed. Moreover, human activities, like residential and commercial development, could degrade water quality because, depending on the season, this area supports a population of 50,000-200,000 individuals.
A watershed Memorandum of Agreement New York City water managers have been occupied since 1986 with the problem of developing a watershed protection program to satisfy the SWTR while maintaining cooperation from upstate residents. Ini4 6 6 A • NOVEMBER 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
tial attempts to regulate land use in the watershed region met with strong opposition from watershed area residents who feared that economic development would be stifled, property values would drop, and the local tax base would erode. Starting in 1995, representatives from New York City, EPA, and upstate communities met periodically to draft a New York City Watershed Memorandum of Agreement (MOA). The MOA, which extends the city's filtration waiver until April 2002, serves as a blueprint for the city's watershed management strategy for the Catskill/ Delaware supply and will cost approximately $1.5 billion over 10 years. Its three major components are listed in Table 1. EPA's acceptance of the MOA was influenced by the Watershed Agricultural Program, created in 1993 in response to the MOA's watershed management mandate. Farmers expressed concerns that land use restrictions would hamper productivity. "Farmers estimated that as much as 25% of their tillable land would be taken out of production if agriculture was regulated under the MOA," says program leader Dick Coombe. Because the region's 35,000 dairy cows are a possible source of pollutants to the city's water supply, New York City and EPA made arrangements with the farming community to establish the voluntary program in lieu of including agriculture as a regulated activity under the MOA. Not all parties were completely satisfied with the MOA, and in early 1997, the National Research Council (NRC) was approached to assess its scientific underpinnings. After two years of deliberation by an expert committee, the NRC produced a report, which considers whether a strategy based on watershed management without filtration can achieve a water supply with an acceptable level of risk to public health and the environment (i). "The report is the benchmark for all serious policy considerations [regarding the watershed management program]," says Nancy Anderson of the New York City Office of the Comptroller, which sponsored the study. The report identifies three issues that will shape the future of watershed management in water supplies across the country. First, to achieve the greatest overall risk reduction, watershed management must be directed at the most polluting activities within a watershed, and it must consider the relative impact of various pollutants. Like many other eastern water supplies, New York City is focusing heavily on phosphorus because of its role in eutrophication and the formation of disinfection byproducts (DBPs). In the future, water supplies will be expected to protect against microbial pathogens, toxic compounds, and DBPs in the face of increasingly strict standards. This challenge is especially acute for water supplies that rely on chlorine disinfection their sole treatment process Second, watershed management will affect future economic growth in the source region. New York City's strategy of compensating watershed residents for the imposition of watershed regulations by investing in their economy poses several significant questions. Will this type of monetary investment in the watershed region lead to development
that adversely affects water quality? Can such a strategy reduce the impact of future population growth on water quality? Finally, many stakeholders in New York City perceive a distinct trade-off between filtration and watershed management. "The adoption of a strategy that incorporates both filtration and watershed management would lead to a loss of public commitment to the high level of environmental conservation reflected in the present strategy of watershed management and chlorine disinfection," says Eric Goldstein of the Natural Resources Defense Council. This perceived conflict has substantial implications for the success of watershed management in New York City and other unfiltered supplies.
A sound, workable basis? The MOAs scientific programs were assessed by comparing them with the components of an ideal watershed management strategy, conceptualized in Figure 2 {1-3). Goal setting, watershed inventories, protection strategies, effectiveness monitoring, and stakeholder involvement exist to varying degrees within the MOA. Part of the goal-setting process involves deciding what are the contaminants of concern, given the biogeophysical setting of the watershed, the probable sources of contamination, and the susceptible
population. The NRC committee found that New York City's pollutant priorities were not appropriate in terms of resource allocation. In particular, it recommended that the watershed management program place importance first on microbial pathogens, second on organic precursors of DBPs, third on phosphorus, and fourth on turbidity and sediment. "The prime focus of New York City's efforts in protecting the health of its consumers should be on pathogens in the water supply and developing means for their control," states the report. Compared with phosphorus, considerably less effort has been expended developing monitoring and modeling tools for microbial pathogens, which pose a more significant and direct threat to public health and are the primary target of the SWTR An inventory of the watershed and an assessment of potential contaminants help to define the boundary conditions and basis for watershed management programs. New York City is well equipped to conduct such inventories because of its extensive monitoring system and well-developed Geographic Information System. In addition, it has spearheaded the development of Total Maximum Daily Load (TMDL) calculations for determining the relative importance of different land uses in contributing total phosphorus to nearby streams and reservoirs. The NRC report recommends that New York
TABLE 1
Key provisions of the MOA Land acquisition and watershed rules and regulations, as well as protection and partnership programs, are key provisions of the New York City Watershed Memorandum of Agreement, which serves as the blueprint for the city's watershed management strategy for the Catskill/Delaware water supply.
Component
Description
Cost
Land Acquisition Program
Allows New York City to acquire fee title or conservation easements to vacant water-quality-sensitive watershed lands on a "willing buyer/willing seller" basis. Titles and conservation easements are held in perpetuity. Areas closer to reservoir intakes and lower in the watershed are given higher priority for acquisition.
$250 million
Watershed Rules and Regulations
Controls a wide variety of pollution sources such as wastewater treatment plants, on-site sewage treatment and disposal systems (septic systems), stormwater runoff, and storage of hazardous materials. The regulations contain m i n i m u m treatment requirements for some technologies. There are prohibitions on a variety of activities in close proximity to streams, reservoirs, and wetlands. For example, the siting of wastewater treatment plants; septic systems; storage facilities for hazardous materials, petroleum, and salt; and the construction of impervious surfaces are all restricted within "setback" distances f r o m major water bodies.
Variable
Watershed Protection and Partnership Programs
Variety of programs intended to preserve the economic and social character of watershed communities while maintaining and enhancing water quality. The Catskill Watershed Corporation, a not-for-profit corporation, was formed to manage these programs for the Catskill/Delaware watershed region. Programs include infrastructure improvements, development, conservation, and education.
$240 million
Source: Reference (J).
NOVEMBER 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS * 4 6 7 A
FIGURE 2
Components of watershed management Goal setting, watershed inventories, protection strategies, effectiveness monitoring, and stakeholder involvement exist to varying degrees within the Memorandum of Agreement's scientific programs. These were assessed by comparing them with the components of an ideal watershed management strategy.
Source: Adapted from References [2, 3).
City expand its TMDL program to focus more on public health protection by developing models that link phosphorus to DBP precursors and other relevant parameters such as DBP formation potential, algae, chlorophyll, and taste and odor. "Going beyond total phosphorus would put New York City on the cutting edge of TMDL development and require innovative new models," notes NRC committee member Jerry Schnoor of the University of Iowa.
Protection strategies Comprehensive watershed management uses multiple protection strategies to prevent contaminants from reaching surface water and groundwater resources. To help expedite the use of new scientific information during selection and implementation of these protection strategies, the report recommends that New York City develop a regular scientific external review and advisory process. As the following examples demonstrate, the injection of new science into the watershed management plan has been variable. Disparities between state-of-the-art science and on-the-ground implementation are apparent in the MOA's use of setbacks, stormwater Best Management Strategies (BMPs), and some wastewater treatment technologies. Stormwater: Multiple setbacks are proscribed in the MOA to specific activities such as storage of hazardous waste and petroleum products, siting of septic systems and landfills, and creation of new impervious surfaces from nearby wetlands, streams, and reservoirs. The NRC report warns that the setback distances make no mention of land characteristics 4 6 8 A • NOVEMBER 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
known to influence pollutant removal in buffer zones such as slope, hydraulic conductivity, and vegetation or surface roughness. In particular, it states that "areas with a slope greater than 15% generally do not function as effective buffer zones," suggesting that such areas not count toward setback delineation. Active management of setbacks, such as converting channelized flow to sheet flow upslope from the setback, using appropriate vegetation, and harvesting vegetation to remove accumulated pollutants, is strongly recommended. Several of the MOA setbacks were found to be inadequate in width, based on recent studies that examined pollutant transport through experimental buffers. For these reasons, the report states that setbacks "should not be relied upon to provide the sole nonpoint source pollution control, and cire instead best used when integrated with appropriate source controls on pollutant releases" The MOA appears to place a disproportionate burden on a management strategy that is marginally effective in many situations Other stormwater BMPs used extensively in the MOA include structural methods like detention ponds and sand filters to reduce pollution from stormwater. NRC committee member Tom Schueler of the Center for Watershed Protection notes that "unfortunately, for removal of both phosphorus and bacteria from stormwater, current structural BMPs advocated by New York City are only moderately effective. In almost all cases, these BMPs cannot completely counteract the effects of new development on pollutant loading levels." To counteract deficiencies in structural urban stormwater BMPs, the NRC report encourages the use of nonstructural BMPs that will limit the amount cind iixipact of impervious surfaces. Because stormwater BMPs are such an essential part of New York City's watershed management plan the report stresses that implementation and l o n g - t e r m m a i n t e n a n c e of BMPs m u s t be addressed "Experience in other localities has shown that BMPs are often not fully implemented long-term maintenance of BMPs is difficult to achieve and as a result BMP effectiveness decreases with time " s'avs Theo Dillaha with Virginia Polytechnic Institute and State University Wastewater: The MOA mandates ssgnificant upgrades to the 41 wastewater t r e a t m e n t plants (WWTPs) that discharge into the watershed, including the use of microfiltration or its equivalent. The NRC committee was satisfied that die upgrades would reduce effluent loadings of phosphorus, total suspended solids, coliforms, viruses, Giardia, and Cryptosporidium. The technology being used in lieu of microfiltration at the majority of plants—continuous backwash upflow dual sand filtration—was deemed appropriate only if these units are subjected to rigorous long-term monitoring of particle counts and turbidity. In contrast, the committee objected to current technologies for new and replacement septic systems in the watershed as inadequate and not representing best available control technology. The report recommends the installation of aerobic treatment units and accompanying enforcement efforts such as annual inspections
One of the MOA's unique strategies for controlling wastewater is the five-year phosphorus offset pilot program, which allows for the construction of up to six newWWTPs in pollution-sensitive basins. This program, one of the first pollution trading schemes in the United States, intends to allow for continued growth in the watersheds while preventing a net increase in phosphorus loading. The NRC report criticizes the 3:1 and 2:1 offset ratios, which indicate the amount of pollutant reduction that must occur to balance a new discharge. In addition to providing a safety margin to account for variable BMP performance and other errors, the offset ratio should reflect the spatial and temporal variability of offset mechanisms the relative locations of the offset mechanism and the WWTP and the different forms of phosphorus produced in the effluent of a ^V^VTP versus the offset mechanism "Because the ratios do not take these issues into consideration they may not afford sufficient protection " says NRC committee member Cindy Paulson of Brown and Caldwell
Monitoring New York City's enhanced monitoring program gathers information that enables the city to comply with water quality regulations, to better operate the water supply system, and to validate water quality models and for special studies. Although the NRC committee found the monitoring program to be informed, extensive, and of high quality, some suggestions for improvement were made. The report recommends that monitoring be conducted on the basis of discharge-mediated volume rather than fixed intervals for stream flow, shallow subsurface flow, and
TABLE 2
Funding the programs MOA negotiators created several major Watershed Protection and Partnership Programs to address local economic development concerns about funding.
Partnership program
Sewage treatment infrastructure Catskill Fund for the Future Storm water fund Septic rehabilitation/replacement Sand/salt storage facilities Sewer extensions Good Neighbor payments Stormwater retrofits State Pollutant Discharge Elimination System upgrades Catskill Watershed Corporation Stream corridor protection Tax consulting fund Alternate design septics Public education Forestry management program Economic development study Source: Reference (7).
Funding (in millions of dollars)
75.00 59.70 31.70 13.60 10.25 10.00 9.76 7.62 5.00 3.50 3.00 3.00 3.00 2.00 0.50 0.50
other analyses. Although partially under way, eventbased sampling will require a greater proportion of effort and resources in the future. The report also notes the absence of regular monitoring of the shallow subsurface and groundwater, which is troubling, given the prominent role of agriculture, the high density of septic systems, and the potential for leaking sewer lines. "New routine groundwater sampling should be integrated with direct experiments on the efficacy of On-Site Sewage Treatment and Disposal Systems [septic systems] and riparian buffer zone [setback] management," states the report. In addition to monitoring water quality, a comprehensive watershed management strategy should include monitoring of public health parameters to confirm that no w a t e r b o r n e disease outbreaks or unacceptable levels of endemic illness are associated with drinking water (i). Since the mid-1990s, New York City has boasted one of the largest and most comprehensive active disease surveillance programs for giardiasis and cryptosporidiosis. "Current rates of these infections are significandy lower than in previous years, primarily because fewer infections are being diagnosed among immunocompromised persons," stated Jim Miller of the New York City Department of Heakh at one the NRC's meetings. Nevertheless, because active disease surveillance frequently suffers from underreporting (only 1 in 22,000 cases were diagnosed and reported via disease surveillance during die Milwaukee, WI, Cryptosporidium outbreak), the NRC report recommends that health care providers and laboratories make Cryptosporidium testing part of all routine stool examinations. In addition, the NRC report suggests mat New York City conduct an epidemiological study, such as a randomized household intervention trial using an in-home water treatment device, to determine the role of tap water as a vehicle of infection. Although such studies are acknowledged to be complex and expensive, the report deems them the most rigorous way to quantify the potential for waterborne disease and provide documentation on the safety of the water supply To complement the active disease surveillance program, the NRC report suggests that New York City conduct regular quantitative microbial risk assessments for Cryptosporidium. "Epidemiological methods are only one tool to estimate potential disease impacts from pathogens in water," states committee member Chuck Haas of Drexel University. "New York City is one of the few cities where enough data are collected to use [risk assessment] on a regular basis." In particular, the report notes that 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. These efforts could help determine the contribution of watershed management (versus other treatment strategies) to overall risk reduction To provide a road map for how this might be accomplished, the NRC report contains a risk assessment on Cryptosporidium oocyst concentrations for the Kensico Reservoir using data collected from January 1993 through July 1998. The daily risk estiNOVEMBER 1, 2000/ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS " 4 6 9 A
FIGURE 3
Population growth trends for the Catskill/Delaware watershed region and 40 West-of-Hudson towns The population of the communities in the Catskill/Delaware watershed has grown very slowly (red); less than half the population of these towns actually resides within the watershed boundary. The estimated permanent watershed population has hardly changed between 1860 and 1990 (green). Using historic trends, the National Research Council report also provides estimates of future population growth trends to 2020 assuming three different growth rates: low, moderate, and high (purple). The estimated watershed population will change little between now and 2020. If the lowgrowth trend that characterized the 1990s were to continue (light blue), the permanent population in 2020 would be greater than the 1996 population by only 2500 persons.
Source: Reference (7).
mate considering all years of data and all sources of uncertainty was 3.4 x 10~5, with a 95% confidence interval ranging from 3.4 x 10~7 to 21.9 x 10 -5 . For an exposed population of 7.5 million, this translates into an estimated 255 infections per day. The report stresses that these calculations are made possible only by using multiple assumptions that, along with the acceptable risk level, must be agreed upon by regulatory agencies, the city, and affected parties.
Stakeholder involvement The MOA, which is signed by 48 separate entities, is testimony to the importance of involving stakeholders in watershed management planning. Complete stakeholder involvement is often difficult to achieve because of the lack of correspondence between political jurisdictions and watershed boundaries and the often contingent and fortuitous nature of community formation. However, compared with many other major federally funded watershed projects, the New York City MOA is a success (i). Reports on the implementation of MOA programs are available on request, and stakeholder forums occur on a regular basis in different regions of the watershed. "We hope that the MOA will educate interested parties to have a more complete u n d e r s t a n d i n g of the consequences of their actions. It is important for individ4 7 0 A • NOVEMBER 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
uals to recognize public benefits that conflict with their particular interests," says committee member Max Pfeffer of Cornell University.
Balancing management and development New York City's goal of protecting its water supply by limiting development activities in the watershed region counters the goals of many watershed residents, who see economic development as a means of improving their standard of living. This tension, which emerged early and persisted throughout the drafting and implementation of the MOA, has been addressed in several ways. First, New York City explicitly promises not to exercise its power of eminent domain, which it is granted under New York State Health Codes. Thus, all land acquisition will be on "willing buyer/willing seller" terms. The MOA also excludes from acquisition land with structures or within the self-defined growth boundaries of towns. The option of conservation easements allows New York City to gain development rights to the land while local owners retain all other property rights. MOA negotiators created the Watershed Protection and Partnership Programs to address local economic development concerns (see Table 2). The Catskill Watershed Corp. will preside over the expenditure of a p p r o x i m a t e l y $240 million in cityprovided funds. One of the largest expenditures, $59.7 million over 15 years, is earmarked for the Catskill Fund for the Future to support responsible, environmentally sensitive economic development. In addition, funds are to be expended for infrastructure improvements that could be conducive to environmental protection, as well as development, such as the construction of new WWTPs or community septic systems or formation of septic districts ($75 million). Finally funds are available for educational and conservation efforts that are likely to improve water quality New York City claims that preserving highquality drinking water and the economic health and vitality of watershed communities are compatible goals and can be met through cooperation and partnership. But are these goals really mutually supportive? To address this question, the NRC committee examined population trends in the region. There are 40 towns with some land in the Catskill and Delaware watersheds for which population trends are shown in Figure 3. Population trends are closely related to economic development, and prospects for economic growth in the Catskill and Delaware watersheds are limited. A recently completed comprehensive overview of the watershed economy shows that the 1990s were a period of economic decline for the area (4, 5). Between 1990 and 1997, the five watershed counties experienced an overall decline in employment of some 7%, and real wages declined in every sector except finance, insurance, and real estate. Tourism and recreation arts and crafts and specialty manufacturing are among the major activities that hold promise for growth but even with the impetus provided bv growth-promoting grams u n d e r the MOA rapid increases in economic activity in the region seem unlikely
Given the region's historic population and economic trends and the MOA's specification that Watershed Protection and Partnership funds be spent on environmentally sensitive development projects, the NRC report concludes that development consistent with maintenance of water quality is a realistic and achievable goal. The NRC committee considered the balancing of development restrictions with incentives to be a sensible strategy for New York City and other communities. However, this is in die context of substantial financial commitments from the city in conjunction with other regulatory, land acquisition and water quality investment programs that will contribute to the protection of the drinking water supply Specifically the committee concluded that population growth and econoinic development activities might be accommodated in the watershed without deleterious impacts on water quality as long as land use regulations are rieorously implemented and the extensive qualitv infrastructure investments now being planned are put in place Water from the Catskill/Delaware system must pass through the Kensico and/or West Branch reservoirs that reside within the Croton watershed—an area that is under significantly greater development pressures than the West-of-Hudson region. Thus, possible trade-offs between water quality and economic development in the Kensico and West Branch basins are important for the integrity of the entire water supply system. Although New York City has made progress in its land acquisition goals around the West Branch Reservoir, EPA has criticized the city for its lack of progress in obtaining property around the Kensico Reservoir (6). The NRC report estimates substantial population growth in these watersheds as much as 200% in West Branch. According to the report, "monitoring reservoir water quality reducing present pollutant loadings via BMPs and preventing future pollutant loading to the Kensico and West Branch reservoirs will be formidable tasks in the face of [these] population pressures"
Watershed management and water treatment In any water supply system, the safety of the water at a consumers tap depends on the ability of watershed management to prevent contaminants from entering the supply and a treatment system to remove or inactivate these contaminants before the water enters the distribution network. These two approaches, which are both independent and interdependent, are major components of a "multiplebarrier approach" to providing safe potable water (7). They are independent because the effects of a breakdown in one can be minimized by the effectiveness of the other. They are interdependent in that the safety of the potable water depends on both. Watershed management may also influence the efficacy of filtration. Preventing pollutants from entering a supply and removing the remaining pollutants from that supply both reduce risks to public health and enhance safety. This complementarity complicates decisions about investment in public water supply. For New York City and many other supplies, both watershed management and water treatment are feasible and should
be implemented. Arriving at an appropriate allocation of funds and other resources between these two barriers is, however, a complex issue. When conventional treatment is put in place, watershed management is often neglected: Raw water quality can deteriorate; an important barrier may not be developed; and the treated water's quality can be compromised by unforeseen events in the watershed and in the treatment system. When watershed management is emphasized at the expense of providing adequate treatment similar problems can arise. The appropriate balance involves some basic program for each barrier, with the balance of effort on the two barriers depending on local and regional issues and constraints. The NRC report encourages New York City to be open-minded. Achieving this balance may necessitate management of pathogen inputs to the watershed from agricultural and other nonpoint sources, control of phosphorus inputs to reduce the production of in-reservoir natural organic matter, and management, if possible, of natural organic matter from terrestrial sources. The report also suggests that to combat Cryptosporidium and prevent formation of DBPs, disinfectants other man free chlorine or additional treatment such as filtration may become necessary Thus although the IV^OA is a good template for proactive watershed management that if properly implemented will maintain high water quality in the Catskill/Delaware system it is clear that the MOA is not a guarantee of permanent filtration avoidance (7)
References (1) Watershed Management for Potable Water Supply: Assessing the New York City Strategy; National Academy Press: Washington, DC, 2000. (2) Clements, J. X; et al. Framework for a Watershed Management Program; Project 93-IRM-4; Water Enviionmental Research Foundation: Alexandria, VA, 1996. (3) The Watershed Protection Approach: Statewide Basin Management; WH-55; Office of Water, U.S. EPA, U.S. Government Printing Office: Washington, DC, 1994. (4) West of the Hudson Economic Development Study for the Catskill Watershed Corporation, Report 1: Baseline Economic Analysis and Communtty Assessment; Hamilton, Rabinovitz and Alschuler, Inc., Alle King, Rosen and Fleming, Fairweather Consulting, The Saratoga Associates, and Shepstone Management: New York, June 22, 1998. (5) West of the Hudson Economic Development Study for the Catskill Watershed Corporation, Report 2: Market Sector Assessment & Program Issues Analysis; Hamilton, Rabinovitz, and Alschuler, Inc., Alle King, Rosen and Fleming, Fairweather Consulting, The Saratoga Associates, and Shepstone Management: New York, September 25, 1998. (6) Assessing New York City's Watershed Protection Program: The 1997 Filtraiion Avoidanee Determnnation MidCourse Review for the Catskill and Delaware Water Supply; U.S. EPA Region 2, U.S. Government Printing Office: Washington, DC, May 31, 2000. (7) Notice of Data Availability for the Enhanced Surface Water Treatment Rule; 815/2-97-00; Office of Water, U.S. EPA, U.S. Government Printing Office: Washington, DC, 1997. Laura J. Ehlers is a senior staff officer of the National Research Council's Water Science and Technology Board. MaM J. Pfeffer is an associate professor in the Department ofRural Sociology at Cornell University. Charles R. O'Melia is the Abel Wolman Professor of Environmental Engineering in the Department of Geography and Environmental Engineering at Johns Hopkins University. NOVEMBER 1, 2000/ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS " 4 7 1 A
