Clearwater Lake reaching capacity; overspill possible depending on rain

Tuesday, May 3, 2011

PIEDMONT, Mo. -- With 4 inches of rain in the 48 hours ending at 7 a.m. today, Clearwater Lake is now at its third highest level and possibly could go over the spillway sometime Tuesday.

"We are nearing the top of the lake's flood storage capacity at elevation 567 feet. We have been holding back water to protect Poplar Bluff and areas downstream, but with the additional rainfall we started releasing 2,000 cfs and increased the release to 4,000 cfs at 6:30 a.m.," Clearwater Lake Operations Manager Tim Dunn said today.

At 9 a.m. today, the lake was at 563.72 feet, an increase of nearly 2 feet in the past 24 hours. In, 2008, the lake crested at 563 feet. The second highest level was 565.55 feet in May 1957, and the record was set at 566.60 feet in May 2002.

"We intend to stage releases so it will not go over the spillway. The Black River level at Poplar Bluff should be receding by the time the released water gets there," Dunn said. "We don't think the releases will add to the flooding."

Highway 34 at Patterson is closed due to the high lake level.

At 9:15 a.m. today, the Black River had risen to 17.77 feet and is overflowing the levees again southeast of Poplar Bluff which were damaged by floodwaters last week, The river is 7 feet higher than the low mark of 10.74 feet at 3:15 a.m. Sunday. It had previously crested at 21.41 feet at 4:45 a.m. on April 26.

Since April 22, the rainfall at the Poplar Bluff Municipal Airport has totaled 20.71 inches, according to the National Weather Service at Paducah, Ky.

Clearwater Dam is operating as it should and is reducing flood damage downstream. In fact, if not for the dam, flows at Poplar Bluff would have been up to four times higher last week. This is what Clearwater was designed and constructed to do.

"We are working closely with local Emergency Management Agency officials and sharing information with the communities at most risk," Dunn said.

Engineers are keeping a watchful eye on weather forecasts. The National Weather Service expects an additional 1 to 1.5-inches of rain today and Tuesday. The lake has captured a huge amount of runoff from intensive rains last week.

This could leave the lake vulnerable in coming weeks to having small rains fill the limited remaining flood storage. If that occurs, the dam will continue to hold all the water currently stored in the lake, however, water still entering the lake could flow over the overflow spillway, which is at elevation 567 feet.

It would be as if Clearwater Dam was not there, and the Corps would not be able to regulate the river stage. River flows would be as they were in their natural state before the dam was built until the lake level returns below the rim of the overflow spillway.

Therefore, smaller rains could cause higher river stages downstream of the dam than the recent heavier rains did.

As Clearwater nears its capacity and more rain is in the forecast, people should decide beforehand whether to move livestock, equipment and belongings to higher ground. The river would rise more quickly in areas closer to the dam. Large releases can occur during heavy rain with no more than an hour or two notice, and rapidly changing conditions could create even shorter notice.

People in at-risk areas should stay in contact with local emergency officials. If larger than normal releases are required from the dam, warnings will go out through local emergency channels. Local officials may not know you require notification unless you have told them so.

Army Corps of Engineers personnel are monitoring lake levels and maintaining 24-hour surveillance, and the dam is sound. Personnel from the Corps' Clearwater Lake Project Office are staying in contact with state and local officials to coordinate public safety information.

"Do not rely on rumors. If you have questions, call the Clearwater Lake project office. You can also call 573-223-7777 and select "option 5" to get current lake elevations. In addition, information is posted on the Internet at www.swl.usace.army.mil ," Dunn said.

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