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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.



Neversink Reservoir

Flexible Flow Management Program Summary
The Operations Support Tool (OST) Flexible Flow Management Program (FFMP) Summary is a set of graphs and tables that summarize the model output data supporting each release decision for Cannonsville, Pepacton and Neversink Reservoirs.
OST-FFMP Summary (PDF)




Operations Support Tool
The Operations Support Tool (OST) is a computerized decision support system that guides the managers that operate the New York City Water Supply System.
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Snow Pillows
The snow pillow is a device that measures the amount of water in the snowpack for a watershed area. Snowpack water is important to the water supply because melting snow drains into reservoirs. The snow pillows provide continuous, real-time data on snowpack water content, and is a major component to accurate modeling.
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Useful Links & Resources
Links to resources for weather forecasts, reservoir levels and more.
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Reservoir Levels

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Normal: %