Although it's too early for the tracking forecasts to predict how much of Hurricane Irene's rainfall will extend into northeastern Pennsylvania, George Sauls is taking no chances.
Sauls, the Northern Area engineer for the U.S. Army Corps of Engineers, oversees five dams in northeastern Pennsylvania, including the Francis E. Walter Dam – the major reservoir for the Lehigh River basin.
"In anticipation of Hurricane Irene, we are going to start lowering the recreation pool at Francis E. Walter Dam," Sauls explained.
About 2,000 cubic feet per second was dumped on Thursday afternoon. Necessary, the flow was to be increased to 3,500 cfs. today.
"As Irene gets closer, and the forecasts become more reliable, we may adjust accordingly," he continued. "Right now, we are on the edge of Irene. A small change in the path could have a big impact on precipitation."
Thursday's forecast called for the brunt of the storm to hit Pennsylvania on Sunday, probably with rain beginning on Saturday night. If the storm remains off shore, its winds and rainfall could extend 250 miles, which would put northeastern Pennsylvania toward the edge of the storm.
Because of an already wet August, the F.E.W. Dam is already at its maximum recreational storage level at 1,370 feet above sea level. Before the formation of Irene, the Corps had been storing water for a late fall mega-release. For several years, the Corps has been using a Lehigh River flow management plan of summer water releases for fishing and paddling enthusiasts. But recreational storage is secondary to its primary mission flood control.
Because of the billions of gallons stored in the reservoir above the dam, actions to lower the level must be taken days in advance. The outfitters have been notified about the unscheduled water release, and may plan to have guides in each raft or use larger rafts if the release is at a high enough level.
Once the rainfall from the hurricane reaches the area, the gates at the dam close and it begins to store water to limit potential down stream flooding.
"We wait for the peaks downstream to drop off and then we release as quickly as we can without aggravating downstream systems," Sauls said. "Our maximum allowable flow is 10,000 cfs. but we have maxed at 8,000 cfs. We will try to return the reservoir to normal pool level 1,370 feet or a little less as is required to meet recreation levels."
The highest pool on record occurred in 2006 when a non-hurricane storm rose F.E.W.'s reservoir to 1,442 feet, just eight feet short of the overflow spillway.
A storm in May of 1942 raised interest in creation of a dam to reduce flooding on the Lehigh River. In 1955, Hurricanes Connie and Diane renewed the interest, and the F.E.W. was operating in 1960.