The Delaware River Basin Commission Wednesday announced the termination of its drought management special permit in effect since November 23, 2016, when the basin was placed in a drought watch.
“Due to recent precipitation and snowmelt, combined storage in three large upper basin reservoirs has achieved and sustained a sufficient level for five consecutive days to result in automatic termination of the basinwide drought watch,” said DRBC Executive Director Steve Tambini.
“Although upper basin reservoir storage has rebounded in recent weeks automatically ending the drought watch operations, other indicators such as groundwater levels, stream flows, precipitation, soil moisture, and local reservoir storage have not all recovered,” said Tambini. “As a result, various state-issued drought watches and warnings based on those indicators remain in effect across most of the basin.”
“DRBC continues to urge all water users to maximize water efficiency wherever possible and to fully cooperate with requests by the basin states to curb water use where drought watches and warnings have been issued based on local conditions,” added Tambini. “The importance of a coordinated response by all water users cannot be overstated.”
The DRBC’s primary drought management objective, which complements the basin states’ drought response efforts, is to provide for conservation of regional reservoir storage for purposes of water supply and flow augmentation in the Delaware River and salinity control in the Delaware Estuary (i.e., the tidal river and bay).
The upper basin reservoirs which determine DRBC drought stages are located in the Catskill Mountains at the headwaters of the Delaware River in New York State.
These three New York City reservoirs provide about half of the city’s water supply and support a minimum flow target in the Delaware River at Montague, N.J. established by the U.S. Supreme Court Decree of 1954.
Storage, releases, diversions, and flow targets in the DRBC drought management plan are determined in advance and must have the unanimous concurrence of the parties to the decree, which include the four basin states and New York City.
Combined storage in the three upper basin reservoirs had been as low as 39.3 percent of capacity in late November 2016. The reservoirs are currently at about 58 percent of capacity, which is approximately 70 billion gallons below normal for this time of the year.
By transitioning out of the drought watch stage, out-of-basin diversions to New York City and portions of New Jersey established by the decree will return to normal levels.
In addition, the Delaware River flow objective at Montague and a second flow objective at Trenton, N.J. will also return to the normal targets of 1,750 cubic feet per second (cfs) and 3,000 cfs, respectively.
The purpose of the Trenton flow objective is to control the movement of the “salt line” or “salt front” in the tidal Delaware River.
Adequate freshwater flowing downstream is needed to repel the upstream migration of “salty” or “brackish” water from the Delaware Bay to keep it away from drinking water intakes serving residents in Philadelphia and New Jersey, as well as industrial intakes along the river.
As of January 16, thanks to increased downstream flows, the salt front was located at river mile 73, which is four miles upstream of the normal January location.
The salt front reached river mile 90 in late November-early December, which was well above the normal location but still 20 miles downstream of water supply intakes in Pennsylvania and New Jersey.
“Cooperation from the states, from New York City, and from water users and managers has been effective during the basinwide drought watch period,” said Tambini. “Although recent trends in storage volume and the location of the salt front have been positive and DRBC is required to move from ‘drought watch’ status back to ‘normal’ status, the volume of water in the reservoirs and other indicators suggest additional cooperation and water efficiency are still needed.”For more information, visit DRBC Drought webpage.