Science & Technology
6:27 pm
Wed October 31, 2012

Low Reservoir Levels, Nearby Snowfall Helped Lessen Flooding Risk from Sandy

Aside from a few wind gusts and steady rain, Pittsburgh was spared from the wrath of Hurricane Sandy.  With the worst of the storm now behind us, officials are breathing a sigh of relief.  Initially, it was feared the excessive rains would mean heavy flooding in the Pittsburgh region, but less rain over the summer helped the situation.

“We were so dry for so long that reservoirs like Youghiogheny Lake was something like 25 feet below normal for this time of year, so it only came up three feet overnight, and we expect it to come up a lot more but we have to make average first before we have too much water, so from a reservoir standpoint we’re in good shape,” said Werner Loehlein, chief water manager with the US Army Corps of Engineers Pittsburgh District.

Even other flood mitigation areas kept up with the storm.

“Our single-purpose projects for flood control like Conemaugh and Loyalhanna did come up about 15 feet, and we expect them to come up some more. So water coming down the Kiskiminetas River into the Allegheny, we’ll probably start to open that up slowly and release the excess once all the rivers are closer to normal.”

While it snarled traffic and caused power outages in West Virginia, snow also helped stem flooding potential here.

“In the western panhandle of Maryland, Garrett County, and into West Virginia, they had a couple of feet of snow – very heavy wet snow, so we somewhat dodged a bullet,” said Loehlein.

That’s because that snow was initially forecast to be rain, but thanks to colder temperatures it’s now sitting in basins, allowing rain to do its thing in the region without adding to the runoff.

“The rain is going to pass through the three rivers first and as it gets a little warmer we’re probably going to have a very slow snow melt, and that will just trickle out,” he said.

With only minor flooding, rain showers will continue on and off for the next couple of days, though Loehlein said there are no major storms predicted on the heels of Sandy, which should help the area stabilize and rivers go down to seasonal levels. The Army Corps of Engineers will continue to monitor the situation along with the National Weather Service, Coast Guard, and US Geological Survey.