U.Va. Climatologist: Recent Rains Recharging Water Supplies, but Groundwater Remains Below Normal

May 15, 2008 — April and May showers have brought some drought relief.

Precipitation during the first half of May, as recorded at the McCormick Observatory was 4.26 inches, which is 180 percent of normal so far, according to University of Virginia climatologist Philip "Jerry" Stenger.

"This marks the second month in a row with above-average precipitation," Stenger said. Precipitation in April was more than 5.5 inches, about 2.3 inches above normal for the month. This follows on the heels of a winter with subpar rain.

While area reservoirs are full, Stenger is concerned about groundwater, which helps feed water supplies in summer. Most groundwater recharge occurs during the winter months, when plants are dormant and cooler weather retards evaporation. After the growing season starts, the plants absorb water near the surface and the sun evaporates much of what is left, preventing it from reaching aquifers.

"The April rain came in under the wire, before the growing season was in full swing," he said. "Stream flows in the county are above normal; some are even at record levels for this time of year. Groundwater levels are trending up, but they are generally still below normal in this part of the state."

A groundwater monitoring well in Gordonsville, which had been very low several months ago, is now "approaching the lower end of the normal range," Stenger said.

"Some areas may experience water supply problems this summer," he said, noting that thunderstorms usually provide a bulk of the rain in the summer. "Thunderstorms can be capricious. They can bring plenty of water to some places and bypass others."

Tropical storms can also add a lot of rain to the area, and Stenger said forecasts are for a "more active than normal" tropical storm season in the Atlantic.

The Rivanna Water and Sewer Authority cited recent rainfall and the resulting stream levels when it lifted its drought watch on May 13.

Over a 12-month period, the area has received about 38.6 inches of rain, which Stenger said is around  10 inches below normal.  The region has been under a drought warning or a drought watch for the past 10 months, which has inspired many water conservation measures.

Through a combination of efforts, such as installing low-flow faucets, increasing efficiency of heating and cooling units and consumer awareness, U.Va. has reduced its water usage by 3 percent over last year for the first three quarters of the fiscal year, while adding 150,000 square feet of space, according to Cheryl Gomez, director of energy and utilities for the University.

From 1997 to 2007, the University has reduced its water usage from 636 million gallons to 477 million gallons, despite increases in the number of people who attend and work at the University.

Water conservation has "really made a difference in helping us manage the water supply over the past year," said Mike Gaffney, chairman of the Rivanna Water & Sewer Authority, in a recent press release. "We now hope that more of our citizens will extend those recent efforts and make water conservation a continuing habit.”