Rain helps, but hope of fast end to drought dampened

Precipitation boosts stream flows, reservoirs

October 18, 2002|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

You can almost hear the gurgle and sigh after Central Maryland's first wet month since April.

With two weeks to go, October's two rainy spells have delivered 3.76 inches of precipitation at Baltimore-Washington International Airport.

That's well above the 3.16-inch norm for the full month of October, making it only the second wet month Central Maryland has seen since August of last year.

That's a start, but not a cure for the region's long-term shortages, water managers said. Water tables and reservoir levels remain near record lows.

"The drought's not over," said Wendy McPherson, a hydrologist with the U.S. Geological Survey in Baltimore. "The drought won't end until ground-water levels return to normal."

That's begun on Maryland's Eastern Shore, where porous, sandy soils permit a quick recharge. But in the Piedmont region west of the Chesapeake Bay, she said, the trickle-down process is slowed by the fractured bedrock beneath the soil.

A USGS monitoring well in Baltimore County "has not responded to the rainfall at all," McPherson said. "It has continued to drop since last June [2001]."

Central Maryland and the Eastern Shore remain under a Level 2 drought emergency. Mandatory watering restrictions remain in force. The airport needs more than 15 inches of surplus rain or snow to erase the deficit that's accumulated since Sept. 1 of last year.

But the beneficial effects of October's rains are visible.

The three-day rain that began Oct. 9, combined with the nor'easter that blew up the East Coast this week, have boosted stream flows to above-normal volumes. The Susquehanna River at Marietta, Pa. was swollen yesterday to more than 170 percent of the median volume for the date.

Without more rain, however, stream flows will quickly return to their near-record lows. "They don't have the ground-water levels to sustain the stream flow," McPherson said.

Baltimore's water customers have consumed more than 26 billion gallons of Susquehanna River water since the city began tapping it in January to supplement its three reservoirs.

The reservoirs, too, have begun to respond to the rain, gaining nearly 2.3 billion gallons since Oct. 7.

By yesterday morning they had risen to almost 45 percent of their combined capacity -- up from less than 41 percent Oct. 7. (The reservoirs were last full in the late spring of last year.)

The water level at Prettyboy Reservoir has risen more than 2 feet in the past 10 days. But it remains more than 43 feet below its crest, at just 19 percent of capacity. Liberty Reservoir was up by less than a foot, to 36 percent of capacity.

Loch Raven Reservoir, which is fed by water released from Prettyboy, has risen about 2 feet, to 81 percent of capacity.

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