Office of the

Delaware River Master

In 1954, the U.S. Supreme Court issued a Decree in State of New Jersey v. State of New York and City of New York in which the Court established the position of the Delaware River Master. The Court directed that the River Master perform multiple duties and functions including administering the provisions of the Decree relating to yields, diversions, and releases; conserving the waters of the river; compiling data on the water needs of the parties; checking and correlating streamflow measurements and records; observing, recording, and studying the effect of developments in the watershed on water supply and other uses; and making periodic reports to the Court.

Since 2007, the Decree Parties have unanimously agreed to a series of Flexible Flow Management Program agreements. On October 21, 2017, the Parties to the Decree (DE, NJ, NY, NYC, PA) signed the 2017 Flexible Flow Management Program (FFMP2017). FFMP2017 is a two-part, ten-year agreement, which guides the current operations of the ODRM.

Flexible Flow Management Program (FFMP2017)


New York State, Pennsylvania, New Jersey, Delaware, and the City of New York 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.

In addition, FFMP2017

  • 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.
  • ccontinues 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 conservation release rates.
  • allows New Jersey to divert 80 million gallons per day (Mgal/d) from the Delaware River Basin through the Delaware and Raritan Canal in a drought emergency.

View all FFMP Documents

Duties and Functions of the Delaware River Master

General Duties

  1. Administer the provisions of the Amended Decree relating to the yields, diversions, and releases of water from the New York City reservoirs.
  2. Conserve the waters in the Delaware River, its tributaries, and in the New York City reservoirs in the Delaware River Basin.
  3. Compile and correlate data on the water needs of the Parties to the Decree.
  4. Check and correlate streamflow gagings on the Delaware River and its tributaries.
  5. Observe, record, and study the effects of development on the Delaware River and on the water supply and other [beneficial] water uses.
  6. Make periodic reports to the U.S. Supreme Court, with copies to the Governors of the four basin States and the Mayor of the City of New York.

Specific Duties in Connection with the Montague Release Formula

  1. Determine the average transit time of the flow between the New York City reservoirs and the U.S. Geological Survey streamflow-gaging station at Montague, New Jersey.
  2. Make a daily computation of what the average flow at Montague observed on the previous day would have been, exclusive of releases from the New York City reservoirs and storage of water in other reservoirs in the Delaware River Basin upstream from Montague, in order to determine the amount that would have been required for exact forecasting.
  3. Calculate the release required from the New York City reservoirs to meet the flow objective at Montague, taking into account all the changes that can be anticipated in runoff from the area above Montague and not under the control of New York City.
  4. As needed, design and direct daily adjusted releases from the New York City reservoirs to maintain the applicable minimum basic rate of flow at the Montague gaging station.

Cannonsville Reservoir.
Photo courtesy of New York City Department of Environmental Protection.

Pepacton Reservoir.
Photo courtesy of New York City Department of Environmental Protection.

Neversink Reservoir.
Photo courtesy of New York City Department of Environmental Protection.

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.

Weekly Reservoir and Release Data

View current data (PDF)

OST FFMP Summary

View current data (PDF)

Summary Table of NYC Consumption

View table (PDF)

Montague Directed Release Design

The data and computations of the various components of flow form the basic operational records required to carry out the River Master's specific responsibilities in connection with the Montague Release Formula. The operational record has two parts:

  • the forecasted flow at Montague, exclusive of controlled releases from New York City's reservoirs, and
  • the segregation of the daily average flow at Montague among its various source components.

At any given time, discharge of the Delaware River at Montague consists of uncontrolled runoff from the area upstream from Montague, and may include water from the following additional sources:

  1. Controlled releases from Lake Wallenpaupack on Wallenpaupack Creek in the production of hydroelectric power.
  2. Controlled releases from Rio Reservoir on the Mongaup River in the production of hydroelectric power.
  3. Controlled releases from the Pepacton, Cannonsville, and Neversink Reservoirs of New York City.
  4. Spill from the above-mentioned reservoirs and Lake Wallenpaupack.

Historical Background

In the 1920's, the States of New York, New Jersey, and Pennsylvania were interested in the development of water supplies in the Delaware River Basin, as a source for meeting their individual needs. Between 1924 and 1927, these States made two attempts to forge an agreement for coordinated development of water supplies. Both attempts, however, were unsuccessful. Faced with little prospect of multilateral agreement, and confronted with water shortages and growth pressures, New York City, which lies outside the Delaware River Basin, in 1928, moved to develop new sources of water supply from within the Basin. This action resulted in a serious interstate conflict and, in 1930, the State of New Jersey brought an action in the U.S. Supreme Court to enjoin the City and State of New York from using the waters of any tributary to the Delaware River. On May 25, 1931, the Court granted New York City the right to withdraw 440 million gallons per day (Mgal/d) of water from two reservoirs the City planned to build on headwater tributaries feeding the main stem of the Delaware River. The impoundments--Neversink on the Neversink River and Pepacton on the East Branch of the Delaware River--became fully operational in late summer of 1955.

The original Supreme Court action, in the form of a decree, stood for 23 years. In 1952, however, New York City filed a petition with the Court, seeking to increase its diversion of Delaware River Basin water for water-supply purposes. As a result, the decree parties--the State of Delaware, State of New Jersey, State of New York, New York City and State of Pennsylvania--returned to the Court, in a dispute over the City's right to divert additional water out of the Basin. An amended decree was consented to by all parties and adopted on June 7, 1954. This decree permitted New York City to increase its withdrawal rate to 800 Mgal/d, contingent upon the City's construction of a third in-basin water reservoir--the Cannonsville impoundment on the West Branch of the Delaware River--which was completed in 1967. In return, under the amended decree, New York City was required to release from its three upper basin reservoirs into the Delaware River a sufficient quantity of water to meet a flow objective of 1,750 cubic feet per second at Montague, N.J., in order to ensure adequate streamflows downriver. The decree also permitted an out-of-basin diversion of 100 Mgal/d to central and northeastern New Jersey through the Delaware and Raritan Canal. A River Master employed by the U.S. Geological Survey was appointed by the Court to administer specific provisions of the amended decree.

Advisory Committee

When the Office of the Delaware River Master was established in 1954, the Director of the U.S. Geological Survey formed an Advisory Committee to provide consultation and guidance on technical, procedural, and policy issues related to River Master operations. Periodic interaction with the Advisory Committee has continued during the 50 years of these operations. Presently, the Advisory Committee participates in bi-monthly calls with the River Master to review the status, progress, and plans for operations, and to discuss water-supply matters of concern in the Delaware River Basin. Members of the Advisory Committee are the representatives of the Governors of the States of Delaware, New Jersey, New York, and Pennsylvania, and the Mayor of the City of New York.

Advisory Committee Members

Delaware State Geologist David R. Wunsch Delaware Geological Survey
New Jersey Acting Assistant Commissioner Michele Putnum New Jersey Department of Environmental Protection
New York Director, Bureau of Water Mark Klotz New York State Department of Environmental Conservation
New York City Deputy Commissioner Paul Rush New York City Department of Environmental Protection
Pennsylvania Deputy Secretary Aneca Atkinson Pennsylvania Department of Environmental Protection

July 16, 2018 Advisory Committee Meeting Summary

On July 16th, there was an in-person meeting of the ODRM Advisory Committee. The meeting included a tour of the new NYC diversion tunnel under construction beneath the Hudson River. The Decree Parties signed an agreement for minor modifications of the FFMP2017 Appendix A to clarify schedules and flow rates for conservation releases. The group received a presentation on ORDM 2018 progress, 2019 budget, and 5-year plan, discussed new Advisory Committee operating procedures and organizational preferences for planned FFMP studies.

Contact Us

Robert R. Mason, Jr.
Delaware River Master
(703) 648-5305
Kendra Russell
Deputy Delaware River Master
(703) 648-5323
Vin Difrenna
Staff Hydrologist
(570) 296-7213