Report of the River Master of the Delaware River for the period December 1, 2017–November 30, 2018

Executive Summary 

A Decree of the Supreme Court of the United States entered June 7, 1954 (New Jersey v. New York, 347 U.S. 995), established the position of Delaware River Master within the U.S. Geological Survey. In addition, the Decree authorizes the diversion of water from the Delaware River Basin and requires that compensating releases from certain reservoirs owned by New York City be made under the supervision and direction of the River Master. The Decree stipulates that the River Master provide reports to the Court, not less frequently than annually. This report is the 65th annual report of the River Master of the Delaware River. The report covers the 2018 River Master report year, from December 1, 2017, to November 30, 2018.

During the report year, precipitation in the upper Delaware River Basin was 60.39 inches or 136 percent of the long-term average. On December 1, 2017, combined useable storage in the New York City reservoirs in the upper Delaware River Basin was 193.230 billion gallons or 71.3 percent of the combined useable storage capacity of 270.837 billion gallons. The reservoirs had a usable capacity of 99.5 percent on May 31, 2018. Combined storage remained high (above 80 percent combined capacity) and did not decline below 80 percent of combined capacity through November 30, 2018. River Master operations during the year were conducted as stipulated by the Decree and the Flexible Flow Management Program.

Diversions from the Delaware River Basin by New York City and New Jersey fully complied with the Decree. Reservoir releases were made as directed by the River Master at rates designed to meet the flow objective for the Delaware River at Montague, New Jersey, on 42 days during the report year. Interim Excess Release Quantity banks and conservation releases, designed to relieve thermal stress and protect the fishery and aquatic habitat in the tailwaters of the reservoirs, were also made during the report year.