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Threat Of Flash Flooding In Maryland Increasing With Record Ground Water Levels

BALTIMORE (WJZ) -- Heavy rain from thunderstorms produced a massive flash flood in Ellicott City in May, and it feels like it's been raining ever since.

It all adds up:

"Like at BWI, they had about 17 inches of rain, and normally we would get three and a half inches in a month. And so far this month, we've had seven inches at Baltimore," said Wendy McPherson, with the United States Geological Service.

The U.S. Geological Service tracks stream flows and ground water levels in Maryland.

"We're very saturated, so the river levels are high, the ground water levels are high," McPherson added.

A graph for groundwater levels in Baltimore County shows stream flows at near and record levels.

"You see how it's climbed, and in August, it was setting a record high," McPherson said.

With so much water present, it won't take much rain to cause a flash flood.

"Only one-half inch to an inch, if that's over a short period of time, a couple of hours, that could cause flash flooding," she added.

The science of tracking water can sometimes become personal.

"My daughter had a flash flood where a foot of water went through her house," McPherson added.

Her daughter recorded it from her Harford County roof last month. The same flash flood that claimed two lives.

If heavy amounts of rain continue into autumn, the threat of flash floods will continue as well.

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