New York City's municipal water supply system provides about 1 billion gallons of drinking water a day to over 8.5 million people in New York City and about 1 million people living in nearby Westchester, Putnam, Ulster, and Orange counties. The combined water supply system includes 19 reservoirs and three controlled lakes with a total storage capacity of approximately 580 billion gallons. The city's Watershed Protection Program is intended to maintain and enhance the high quality of these surface water sources. Review of the New York City Watershed Protection Program assesses the efficacy and future of New York City's watershed management activities. The report identifies program areas that may require future change or action, including continued efforts to address turbidity and responding to changes in reservoir water quality as a result of climate change.

In 1997, New York City adopted a mammoth watershed agreement to protect its drinking water and avoid filtration of its large upstate surface water supply. Shortly thereafter, the NRC began an analysis of the agreement's scientific validity. The resulting book finds New York City's watershed agreement to be a good template for proactive watershed management that, if properly implemented, will maintain high water quality. However, it cautions that the agreement is not a guarantee of permanent filtration avoidance because of changing regulations, uncertainties regarding pollution sources, advances in treatment technologies, and natural variations in watershed conditions. The book recommends that New York City place its highest priority on pathogenic microorganisms in the watershed and direct its resources toward improving methods for detecting pathogens, understanding pathogen transport and fate, and demonstrating that best management practices will remove pathogens. Other recommendations, which are broadly applicable to surface water supplies across the country, target buffer zones, stormwater management, water quality monitoring, and effluent trading.

A collection of photographs which profile the aqueducts, reservoirs, tunnels, gatehouses, and tanks of New York's water system.

Supplying water to millions is not simply an engineering and logistical challenge. As David Soll shows in his finely observed history of the nation’s largest municipal water system, the task of providing water to New Yorkers transformed the natural and built environment of the city, its suburbs, and distant rural watersheds. Almost as soon as New York City completed its first municipal water system in 1842, it began to expand the network, eventually reaching far into the Catskill Mountains, more than one hundred miles from the city. Empire of Water explores the history of New York City’s water system from the late nineteenth century to the early twenty-first century, focusing on the geographical, environmental, and political repercussions of the city’s search for more water. Soll vividly recounts the profound environmental implications for both city and countryside. Some of the region’s most prominent landmarks, such as the High Bridge across the Harlem River, Central Park’s Great Lawn, and the Ashokan Reservoir in Ulster County, have their origins in the city’s water system. By tracing the evolution of the city’s water conservation efforts and watershed management regime, Soll reveals the tremendous shifts in environmental practices and consciousness that occurred during the twentieth century. Few episodes better capture the long-standing upstate-downstate divide in New York than the story of how mountain water came to flow from spigots in Brooklyn and Manhattan. Soll concludes by focusing on the landmark watershed protection agreement signed in 1997 between the city, watershed residents, environmental organizations, and the state and federal governments. After decades of rancor between the city and Catskill residents, the two sides set aside their differences to forge a new model of environmental stewardship. His account of this unlikely environmental success story offers a behind the scenes perspective on the nation’s most ambitious and wide-ranging watershed protection program.