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Welcome to the Office of the Delaware River Master (ODRM)

The Office of the Delaware River Master was established to administer the provisions of the 1954 Supreme Court Decree, conserve the water of the river, compile and correlate streamflow data, observe, record, and study the effects of development on the river and water supply, and make periodic in reports to the Supreme Court.

Delaware River Basin States and New York City Announce Ten-Year Reservoir Operating Plan Agreement

MILFORD, Pa. (October 21, 2017) - New York State, Pennsylvania, New Jersey, Delaware, and the City of New York today announced that they have unanimously approved a ten-year, two-part Flexible Flow Management Program (FFMP2017) intended to meet water supply demands, protect fisheries habitat downstream of the New York City (NYC) Delaware Basin reservoirs, enhance flood mitigation, and repel the upstream movement of salt water in the Delaware Estuary.

Releases of water from the three NYC reservoirs (Pepacton, Cannonsville, and Neversink) located in the headwaters of the Delaware River, and out-of-Basin diversions, are managed according to procedures unanimously agreed to by the four states and NYC under the terms of a 1954 U.S. Supreme Court Decree that settled an interstate water dispute between New York State and New York City, and the lower basin states.

FFMP2017 is predicated on broad compromises involving all of the Decree Parties and responds more fully to public inputs and commentary. It establishes four water banks to support specific flow needs and targets an increase in reservoir voids to as much as 15 percent during portions of each year in order to reduce the likelihood of flood-flow releases from the reservoirs.

FFMP2017 includes a commitment by the parties to conduct focused studies during the first 5-years of the agreement to resolve outstanding issues such as the detachment of reservoir releases from the positioning of the Delaware Estuary salt-front during drought emergencies; the impact of New Jersey water-supply diversions during drought conditions; and the availability of increased water storage capacity in the lower basin.

Contingent on satisfactory progress during first 5-years of the agreement, the parties may agree to the second 5-year portion that could include follow-on actions such as implementation of the "salinity detachment", improvements to the operations of the Delaware River Master, and identification and stipulation of the method for calculating the "Excess Release Quantity" that is described in the 1954 Decree.

FFMP2017, which will go into effect on October 20, 2017, will continue to rely on use of the City's Operations Support Tool (OST) to manage water forecasted to be available in the three NYC reservoirs and help guide selection of reservoir release rates (Appendix A). The OST is a sophisticated monitoring and modeling system that allows for better predictions of reservoir-specific water storage levels, quality, and inflows than previous tools. The progressively evolving OST has proven to be a very useful tool in managing the FFMP.

Release rates in FFMP2017 are patterned after recommendations provided in a January 2010 joint fisheries paper prepared by the New York State Department of Environmental Conservation and the Pennsylvania Fish and Boat Commission.

NYC will create a higher potential to achieve a 15 percent storage void in its Delaware Basin reservoirs from November 1 through the following February 1 to help mitigate flooding events. This program may help reduce peak spill rates during periods of high inflows and heavy snow melt. A significant fraction of the snow pack present in the watershed of the NYC reservoirs is included when calculating void promotion releases.

In addition, reservoir releases will continue to be adjusted as needed to assist in repelling the upstream migration of salt water from the Atlantic Ocean that moves up the tidal Delaware River during low-flow conditions. As salt water moves upriver, the City of Philadelphia and other public water suppliers can be adversely affected, along with industrial surface water users and ecosystems. New studies and hydrologic modeling efforts will also include projections of future sea-level rise that can affect salinity in the lower Delaware River.

FFMP2017 allows New Jersey to divert 80 mgd from the Delaware River Basin through the Delaware and Raritan Canal in a drought emergency.

Additional details, including the FFMP agreement and OST background information, can be viewed on the web site of the Office of the Delaware River Master, which administers the provisions of the 1954 U.S. Supreme Court Decree, at

FOR ADDITIONAL INFORMATION CONTACT: Robert Mason (703)648-5305, U.S. Geological Survey, Office of the Delaware River Master.

Provisional Hydrologic Data:

Data presented on the Office of the Delaware River Master website are reviewed periodically to ensure accuracy. The data are considered provisional, however, until they are published in the annual report of the River Master.

Data users are advised to carefully consider the provisional nature of the information before using it for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences.

Information on the accuracy and appropriate uses of the data can be obtained by contacting the Deputy Delaware River Master.

Flexible Flow Management Program (FFMP) and Background Documents

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