 The reservoir itself provides only 2% of NYC's water supply; the rest of the water comes from the reservoirs to which it connects.The water in the reservoir either provides NYC with water, or it travels down the spillway at the southernmost dam, and continues down the rest of the Bronx River, eventually flowing to the East River.The water that does supply New York City travels down either the Catskill Aqueduct or the Delaware Aqueduct.