Watershed Management for Potable Water Supply:

Assessing New York City's Approach


National Research Council

Public Briefing
September 15, 1999

Opening Statement

Charles O'Melia
Professor of Geography and Environmental Engineering
Johns Hopkins University, Baltimore
and
Chair, Committee on Watershed Management for New York City

Good morning. On behalf of the entire committee, I am pleased to be here today to present our report. First, I would like to give you some background on what the National Research Council is and why we were asked to do this study.

The National Research Council is a private, nonprofit organization that provides science and technology advice under a congressional charter. It is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering, all headquartered in Washington, D.C.

In 1997 the New York City Comptroller's Office asked the Research Council to provide a scientific evaluation of the New York City Watershed Memorandum of Agreement. I chaired the 15-member committee that was chosen from a broad range of backgrounds to conduct the study. I want to take this opportunity to thank my fellow committee members who volunteered their time to do this work.The Research Council's study process is highly independent, and as such, the Comptroller's Office was not involved in any way other than requesting and sponsoring the study and providing information and written materials to the committee. I'd like also to point out that the report was peer reviewed by 11 independent scientists to ensure the quality and accuracy of the study.

Now, let me speak to the findings of our committee and the recommendations we made.New York City gets it drinking water from two upstate watershed systems. The Catskill/Delaware system -- which includes five counties west of the city in the Catskill Mountains and with part of the headwaters of the Delaware River -- is the bigger of the two and supplies 90 percent of the city's water supply. The Croton system is north of the city and supplies the remaining 10 percent. We focused on the Catskill/Delaware system for a variety of reasons. The water is delivered to consumers through a massive infrastructure that includes 19 reservoirs and a series of aqueducts and tunnels that span more than 1,900 square miles.

The entire system serves an estimated 9 million people and produces as much as 2 billion gallons of water each day, making it the second-largest single water supplier in the United States. The city's movement toward a comprehensive watershed plan can be traced to more stringent environmental regulations dating from 1989, which require suppliers to filter surface water in addition to disinfecting it. In addition, we did pay particular attention to the Kensico reservoir north of the city, unless a watershed management plan is implemented and other criteria are met. In addition, we did pay particular attention to the Kensico reservoir north of the city.It was New York City's decision to pursue such a plan.

The New York City Watershed Memorandum of Agreement was signed in 1997 after years of negotiations between city officials and representatives from the U.S. Environmental Protection Agency, state government, municipalities around the watershed regions, and environmental groups.This massive agreement calls for a complex combination of programs and policies for land acquisition and management, new health and environmental regulations, and financial assistance to communities for both economic development and watershed protection.

The agreement will allow the city to avoid the need to filter the Catskill/Delaware system until at least 2002 and should help maintain high-quality drinking water over the next several years. As we reviewed the plan, we found it to be a suitable prototype for water suppliers nationwide. It calls for an extraordinary financial and legal commitment from New York City to monitor and prevent existing and potential contaminants from entering the water supply, to conduct new research on health and water quality issues, and to promote the economic well-being of the communities in the watershed region. Nevertheless, we offer some specific suggestions for improvement. For example, we believe that the top priority should be to control microbial pathogens.

Currently, the main target of the city's watershed management strategy is phosphorus, which can play a large role in degrading water quality but by itself is not toxic. If continued filtration avoidance is the goal, then the strongest consideration must be given to preventing microbial pathogens from entering the water supply. Pathogens such as Cryptosporidium and Giardia pose a significant and direct threat to public health because they are very resistant to the chlorination process.

We recommend that New York City incorporate into its plan stepped up efforts to monitor, model, and control these organisms.For instance, it should include a more rigorous strategy to study wildlife, domestic and farm animals, and human wastewater to determine their contributions as sources of microbial pathogens. And water supply managers should test best management practices currently used to control the amount of pollutants entering streams and reservoirs to determine their effectiveness in removing pathogens.

The committee also recommends that a Cryptosporidium risk analysis be performed on a regular basis throughout the watershed to find out the extent to which the city's watershed management strategy is contributing to the reduction of risk from waterborne disease.After pathogens, the watershed plan should place its next highest priority on organic carbon compounds in the water supply. These can lead to the formation of toxic chemicals, known as disinfection byproducts, after reacting with chlorine during the disinfection process. Organic carbon compounds are derived from multiple sources, including decomposed leaves and other plant tissue of terrestrial origin as well as excessive plant and algal growth in reservoirs. Terrestrial sources of organic carbon dominate during certain seasons and are extremely difficult to control.Limiting the input of nutrients in the water supply reservoirs, particularly phosphorus, can control the in-reservoir-generated organic carbon. Phosphorus enters the water supply through a variety of means, including sewage treatment plants, agriculture, and urban storm water. High concentrations of phosphorus can accelerate algal growth and increase the amount of organic matter in the water.

To keep these types of pollutants out of the water supply, the watershed agreement employs programs such as a storm-water pollution prevention effort and a plan focusing on agricultural runoff, designed to protect the water supply from these "non-point" sources of pollution. But the committee found that these types of efforts have proven only partially successful and have not been tested for their ability to control pathogens.For example, one of the most prevalent features of the watershed agreement is the use of "setbacks" to protect wetlands, streams, and reservoirs from pollution by prohibiting certain activities within proscribed distances from a body of water. While the widths of setbacks are defined in the watershed plan, we note that the agreement does not discuss characteristics of the land, such as slope, soil moisture, or vegetation, which all play a role in removing pollutants.

We recommend that these areas be monitored to determine whether the proscribed setback distances are adequate.A major factor in determining the quality of New York City drinking water is the treatment and disposal of waste-water in the Catskill/Delaware watershed. Nearly all of the wastewater from the region either is discharged directly into tributaries that lead to the reservoirs, or seeps below ground, where it eventually reaches the reservoirs. The watershed agreement requires that waste-water treatment plants be upgraded, using the best available technology to control nutrients, dangerous chemicals, and microbes. The committee found that these improvements should be effective in reducing threats to the water supply.However, similar technology upgrades have not been required for septic systems, which serve individual residences.

For those systems that are failing, and for new systems, New York City should install aerobic treatment units, which use mechanical devices to create better oxygen flow within these tanks. Without such action, pollutant loading from septic systems is expected to increase along with population growth.We found that the agreement's overall framework for balancing the need for environmental rules and regulations to protect the watershed and supporting limited development in watershed communities is a sound strategy. While the city plans to spend about $1 billion over the next 10 years to implement its watershed plan, part of the money is earmarked to help communities that may suffer economically as a result of the watershed regulations.Limited population growth and increased economic activity in the watershed region will have some adverse impacts on water quality.

However, in the committee's opinion, the combination of better planning, targeted development, tougher environmental regulations, and improved waste-water management will ensure existing high water quality. Further, we examined existing data that track population trends and found that population growth in the Catskill/Delaware watershed is not accelerating.To preserve environmentally sensitive areas in the watershed, the city also has budgeted $250 million over the next 10 years to purchase land held by private owners. In tandem with this effort, government officials should employ land-use computer models more frequently to better determine specific parcels of land that are contributing to water quality problems.Overall, we find much to applaud in New York City's plan to manage its watersheds.

However, the Memorandum of Agreement is not a guarantee of permanent filtration avoidance. The growing scientific understanding of the impacts of pollutants on human health, changing environmental regulations, and the uncertainties about the origin of specific pollutants demand that the city continually re-evaluate the need to employ filtration or other technologies to keep the water safe.Specifically, we encourage water system managers to continue to consider treatment beyond chlorination to control dangerous pathogens.

Implementing a watershed management plan while investigating treatment processes that could be needed in the future will ensure that no time is lost if additional treatment should become necessary.Watershed management in this case is about protecting the health of the residents of the city while simultaneously protecting the rights of the residents of the watershed.

The memorandum of agreement is a good start. The committee's report builds on it.My fellow panelists and I are now prepared to respond to questions. Because we are recording this event, please step up to the microphone in the center aisle and state your name and affiliation before asking a question. Thank you.