WEST TRENTON, N.J. -- Dry weather stretching back to mid-July has triggered a drought warning in the Delaware River Basin as storage in three major water- supply reservoirs dipped to unseasonably low levels.
The warning was issued by the Delaware River Basin Commission (DRBC) which manages the water resources in the 13,539 square-mile basin, stretching some 330 miles from the Delaware River's headwaters in New York State to the mouth of the Delaware Bay. The Delaware and its tributary rivers and streams drain portions of Pennsylvania, Delaware, New Jersey, and New York.
As stipulated in the Commission's drought operating plan, a maximum withdrawal limit on water diverted out-of-basin to northern New Jersey was cut back from 100 million gallons a day (mgd) to 85 mgd. The water flows by gravity through the Delaware and Raritan Canal, which feeds off the Delaware River north of Trenton and joins the Raritan River in New Brunswick.
The persistent dry weather prompted the Commission to implement other measures of its drought plan early in an effort to preserve water storage in major reservoirs.
Under an agreement reached with New York City in late November, diversions from the city's three huge water supply impoundments in the Catskill Mountains were reduced by 15 percent. Releases from the reservoirs into the Delaware River also were throttled back.
Under normal hydrologic conditions, New York can withdraw up to 800 mgd from the reservoirs -- Neversink, Pepacton, and Cannonsville. In return, it must release sufficient water into the Delaware to meet a downstream flow target of 1,750 cubic feet per second (cfs) at Montague, N.J., located just downstream of Port Jervis, N.Y. In addition, the DRBC directs releases from two lower basin reservoirs to maintain a flow target of 3,000 cfs at Trenton.
Under the agreement with the city, the flow targets have been reduced to 1,655 cfs at Montague and 2,700 cfs at Trenton and New York's take from its reservoirs has been cut to 680 mgd.
The lack of rain, which followed a wet spring, has not only impacted reservoir storage, but has caused significant decreases in streamflows and groundwater levels throughout the basin. There is a seven-inch rainfall deficit in the upper basin (above Montague) going back to July 1. In the Philadelphia region, the deficit for the same period is over nine inches.
Along with the operational changes now in effect, the Commission has called on the basin's seven million residents to voluntarily curb non-essential water use, offering these water saving tips:
"A little common sense and a cooperative spirit go a long way in any campaign to conserve," noted Carol R. Collier, the Commission's executive director. "Hopefully, we can get through this latest water shortage with, at most, just a slight bit of inconvenience."
Ms. Collier noted that we often take water for granted in this country. "In some foreign lands the water comes on at seven in the morning and is turned off at four in the afternoon, and even then it may not be fit to drink," she said. "That's a real hardship, hardly comparable to a short shower."
The DRBC's drought operating plan focuses on salinity intrusion -- the upstream migration of salty water from the Delaware Bay during low-flow conditions in basin rivers and streams.
The salt-laced water, known in water jargon as the "salt front," is defined as a seven-day average of 250 milligram per liter chloride concentration. Since August 1 of this year, the salt front has moved 15 miles upstream and now is located at River Mile 85, about three miles upstream of Chester, Pa., and about eleven miles above its average location for December.
As the front moves upriver, it increases corrosion control costs for surface water users, particularly industry, and has the potential of raising sodium levels in a large aquifer underlying southern New Jersey which is used for municipal water supply. The aquifer is recharged in part by the river.
In recent dry years, salty water also has migrated into streams and creeks in Delaware, threatening water supplies in northern New Castle County.
The drought warning issued by the Commission is the official first step in its drought management plan. Should conditions worsen and a drought emergency be declared, mandatory water-use restrictions would most likely be imposed with a goal of reducing consumptive water use by 15 percent. The out-of-basin diversions by New York City and New Jersey also would be further reduced, as would the Montague and Trenton flow targets.
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