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Study takes look at region's water - Growth areas' quantity, quality is focus

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October 31, 2011

Scientists will sink more than 1.4 miles of wells into northern Kent County and southern New Castle County aquifers in the coming year, hoping to pump out a flood of new information about groundwater quantity and quality in current and future growth areas.

The Delaware Geological Survey and state Water Supply Coordinating Council are collaborating in the work, backed earlier this year by a $600,000 state grant.

Previous studies recommended the new well network to expand a thinly spread system heavily reliant on private utilities and a handful of public water suppliers and individual farm, business and household wells.

"We want to see what the regional picture is," said A. Scott Andres, a senior scientist and hydrogeologist with DGS and a University of Delaware professor. "The goal is to have technical, unbiased science behind decisions to regulate or manage."

Members of the water supply council recommended the studies after droughts in 1995 and 1999 revealed fragmentation and potential supply weaknesses in Delaware's northernmost and most-densely populated areas. Those conclusions led to proposals to develop an additional 2 billion gallons of drought reserves, while also placing environmental protection caps on withdrawals from the creeks and streams that supply about 70 percent of northern New Castle County's needs.

Some of the council's more-recent efforts have focused on areas south of the Chesapeake & Delaware Canal, where groundwater supplies virtually all private taps and public utilities.

Gerald Kauffman, the state's water supply coordinator, said last week that researchers believe Kent and Sussex county shallow aquifers accumulate huge amounts of water, an average of 500,000-700,000 gallons per day per square mile across the two counties' 1,522 square miles.

Although shallow supplies far exceed the area's combined 61 million-gallon-per-day need, pollution and intrusion of salt water from the Delaware Bay and Atlantic Ocean could drive up the cost of using some aquifers or put well fields out of commission. That happened in Millsboro several years ago, when industrial solvent pollution forced the community to abandon a shallow wellfield.

"There are quality issues," Kauffman said. "We have problems with high nitrates and bacteria in some of the shallow wells that are known and significant."

High nitrate levels in well water can pose a special risk for infants or newborn children, affecting oxygen levels in their blood. The pollutant occurs naturally in some locations but more often has been linked to failing septic systems and excessive use of farm and suburban fertilizers, commercial-area runoff and heavy use of poultry and livestock manures on fields.

The latest assessments just south of the canal, Andres said, found that some monitoring wells between the canal and Smyrna are aging and in need of repair and replacement. A follow-up phase, backed by the $600,000 appropriation, will install wells at eight locations, including Blackbird State Forest, Smyrna, the Woodland Beach Wildlife Area, areas near Townsend and Middletown and Odessa National Country Club.

Once installed, existing and new wells will be sampled and monitored regularly for water depth and water quality, providing far more comprehensive information than is now available.

"The project is a relatively modest investment in a resource estimated to be capable of providing 10 million gallons per day of fresh water to an area with the potential for significant growth in water demand," the DGS plan noted. "The outcome will yield compound returns on the investment for years to come."

Use of independently developed data from a wider variety of sources, Andres said separately, "would be a big change for Delaware." Results could help the state better manage water use, limiting withdrawals where excessive pumping could damage aquifers or expanding use where supplies are ample. The new wells also are expected to help scientists better understand the spread of pollutants in shallow and deeper groundwater.

DGS expects the latest part of its study from Smyrna north to take about 30 months. Later phases, Andres said, could allow installation of wells into Potomac Aquifer supplies 3,000 feet below the surface, a depth never before reached for water supply purposes.

"The Potomac formations have the potential to be the largest source of water in the state, but we have very little -- almost no -- information in southern New Castle County," Andres said.

For questions and information, contact DGS at
delgeosurvey@udel.edu, 302-831-2833