WEST TRENTON, N.J. -- A drought warning, which resulted in tightened water supplies for New York City and portions of New Jersey for over two months, ended recently, the result of soaking rains and melting snow in New York's Catskill Mountains.
In January, close to four inches of runoff were captured by three major water supply reservoirs in the Catskills, boosting storage by nearly 60 billion gallons.
The drought warning was issued by the Delaware River Basin Commission on October 27. Under the Commission's drought management plan, a warning ends when combined storage in the three reservoirs increases to at least 15 billion gallons above a designated drought warning zone and stays above that level for five consecutive days. Storage has topped the 15-billion gallon buffer and remained above that level.
The three reservoirs, Pepacton, Neversink and Cannonsville, are located at the Delaware River's headwaters in New York State and account for roughly 75 percent of the total surface water storage in the basin. They are owned by New York City, which is located outside the basin.
The impoundments hold 271 billion gallons of usable water when full. Recently, combined storage was 195 billion gallons or 72 percent of capacity. Normally at this time, the reservoirs are 75 percent full holding 203 billion gallons. Storage recently increased from 136 billion gallons to 195 billion gallons.
With the drought warning now officially over, New York City can once again withdraw up to 800 million gallons of water per day out of the reservoirs for use in the city and outlying areas and New Jersey can divert up to 100 million gallons of water a day through the Delaware and Raritan Canal for use in central and northern portions of the state.
During the drought warning period, both withdrawal limits were reduced by 15 percent and the amount of water released from the reservoirs into the Delaware River also was reduced in an effort to conserve existing supplies. In all, ten billion gallons of water were saved in reservoir storage as the result of these drought management actions.
The Commission's drought plan focuses on salinity intrusion -- the upstream migration of salty water from the Delaware Bay during low-flow conditions in basin rivers and streams.
As part of a pact generated by the Commission among the basin states and New York City, the city must release sufficient water into the Delaware River from its three reservoirs to help repel, or flush back, the salt-laced water, known in water jargon as the "salt front" (a seven-day average 250 milligrams per liter chloride concentration.)
Runoff from the rain and snowmelt have swelled the Delaware and tributary streams, the rush of sea-bound fresh water pushing the salt front downstream to River Mile 70, one mile upstream of the Delaware Memorial Bridge. That's two miles above its average location for this time of year. When the drought warning was triggered on October 27, the salt front was located at River Mile 8J, about two miles north of Chester, Pa., and about four miles above its average location for October.
As the salty water moves upriver it increases corrosion control costs for surface water users, particularly industry, and raises the threat of sodium contamination of a large aquifer underlying southern New Jersey which is used for municipal water supply. The aquifer is recharged in part by the river.
In addition to releases from the three New York City reservoirs, 1.75 billion gallons of water were released from Beltnille Reservoir on the Lehigh River and Blue Marsh Reservoir on the Schuylkill River during the latest water shortage to improve flows, enhance water quality, and protect fisheries. The releases also helped to repel salinity.
Although the drought warning has been lifted, there are still isolated areas in the basin, particularly in Pennsylvania, that have not recovered completely from the drought, or face the potential of water shortages in the future. For instance, in some sections of southeastern Pennsylvania groundwater supplies have not rebounded to normal levels. And the city of Bethlehem faces a potential water supply shortfall because of a failed reservoir that is under repair.
The basin has entered into drought warning nine times since the early 1980s when the Commission's drought management plan was adopted. Two times, in 1981 and 1985, conditions worsened and drought emergencies were declared. The last drought warning occurred in the fall of 1995, and lasted about two months.
The Delaware Basin stretches 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 streams drain portions of Pennsylvania, Delaware, New York and New Jersey.
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