Reservoir Operations and Watershed Monitoring
The Catskill/Delaware system supplies the vast majority of New York City's water. Forecasting reservoir levels in this system is one of the most important and most difficult tasks we face in the operation of the water supply. Reservoir levels are primarily determined by the balance between streamflow into the reservoirs, diversions (withdrawals) for water supply, and releases to maintain appropriate flows in the rivers below the dams. Streamflow is affected by rain and snowmelt, both of which are hard to predict accurately.
Water in the Delaware River Basin is jointly managed pursuant to a 1954 Supreme Court decree that governs water allocations for New York City and the states of New York, Pennsylvania, New Jersey, and Delaware. The Flexible Flow Management Program (FFMP) is intended to provide a more adaptive means for managing releases from Cannonsville, Pepacton, and Neversink reservoirs by providing for releases based solely on the time of year and reservoir storage conditions.