The New York City Department of Environmental Protection (DEP) is the department of the government of New York City that manages the city's water supply.It provides more than 1.1 billion US gallons (4,200,000 m3) of water each day to more than 9 million residents (including 8 million in the City of New York) through a complex network of nineteen reservoirs, three controlled lakes and 6,000 miles (9,700 km) of water mains, tunnels and aqueducts.