Record flood takes out temporary dike, highway at Wappapello Dam

Monday, May 2, 2011 ~ Updated 12:38 PM

POPLAR BLUFF, Mo. -- Historic high waters at Wappapello Dam cut away a nearly 400 foot section of Highway T and much of its $18 million in infrastructure early Monday morning as the lake broke through a temporary dike and roared over the concrete spillway it was shielding. Chunks of pavement and earth 30 to 40 feet deep were carved away by the surging water.

Wappapello Lake is expected to crest this week above any amount seen there before, and is releasing extremely high volumes of water into the already full St. Francis River.

The dam continues to operate as designed, but authorities strongly caution that residents in areas along the St. Francis River prone to flooding be aware of rising water in the coming days. Water may reach levels and locations not seen previously, they say.

Already entrances into Greenville in Wayne County, Mo., above the lake, have been flooded, stopping vehicle traffic in or out of the town. Residents of Qulin worried this morning that the city could find itself in a similar situation before the end of Butler County's second major flood event in two weeks.

No mandatory evacuation orders had been issued within Butler, Stoddard or Wayne counties as of 10 a.m. Residents in affected areas were advised of the dangerous conditions either through door to door canvassing or phone calls.

"We expect to crest at 399.2 feet on Wednesday or Thursday," said Park Ranger Aaron Winchester. "The total discharge will be 23,450 cubic feet per second."

The lake had reached 398.76 feet as of 10 a.m. today, with an outflow of between 13,000 and 15,000 cfs. When the outflow can be controlled, Wappapello is restricted to 10,000 cfs. The previous highest crest was 399.09 feet in 1945.

The crest was calculated based on rain that had fallen as of 3 a.m. and is subject to change, Winchester said. The National Weather Service predicts the Wappapello Dam area could receive another 1 to 1.5 inches of rain by Tuesday. It received more than 4.6 inches in the 48 hours prior to 6 a.m. Sunday.

The overflow could continue for days, dependent on how much additional rain is received, Winchester continued.

Winchester watched this morning as lake water breached a temporary dike constructed to withhold an additional 2.56 feet above the 395.74 foot lake elevation allowed by the permanent emergency spillway.

"It started at 2:08 a.m.," he said. "It was through the temporary (dike) in an hour and a half. The highway was gone 30 minutes after that."

The U.S. Army Corps of Engineers have established temporary headquarters at Redman Creek Picnic Shelter 1 on the south end of the spillway and Bill Emerson Memorial Visitor's Center on the north end of the spillway. Personnel are divided between the two locations, and are traveling from one to the other by boat as needed. An alternate route for Highway T at the dam has not been established because so many roads are flooded.

Winchester said the permanent concrete spillway will be intact when the lake level lowers to its height.

Sections of the temporary dike, constructed from 12,000 tons of gravel, were still in place this morning, but are expected to wash downstream.

The lake was receiving as much as 98,000 cfs, or about 735,000 gallons of water per second, at one point early today.

Officials in Butler and Stoddard counties have begun to organize an emergency response to flooding, which is expected below the dam.

The St. Francis River at Fisk surpassed its previous record of 23.03 feet by 3 a.m. With a flood stage of 20 feet, it was at 23.84 feet at 10 a.m.

It is predicted to crest at 28 feet Thursday. The Missouri Department of Transportation is watching the area closely to see if it will need to close Highway 60.

"Most of the flooding according to (Corps) graphs, shows the water going to Stoddard County," Butler County Emergency Management Agency Director Rick Sliger said today during a meeting with emergency responders. "That hasn't been tested to this degree though. We don't know how (the Highway 60) interchange is going to affect the flow of water."

Other officials noted that charts were created based on dry conditions prior to the flooding event and the area is already saturated with rain. Some areas have received more than 20 inches in the last week and a half.

About 35 members of the Missouri National Guard remain within Butler County to assist with emergency operations.

Much of Southeast Missouri is battling similar flooding conditions and are also in need of resources, officials have noted.

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