News Release 553

Joint Release -- U.S. Geological Survey
Missouri Department of Natural Resources

TAUM SAUK BREACH RELEASED MISSOURI RIVER-SIZED
FLOOD DOWN MOUNTAIN'S SIDE
Water Filled East Fork of Black River Four Times 100-Year Flood Level

Volume 34-553

Contact: USGS -- Paul H. Rydlund
573-308-3572

(For immediate release)

DNR -- Larry Archer
573-751-3807

JEFFERSON CITY, MO, DEC. 14, 2006 -- The breach of Taum Sauk Reservoir one year ago today released a torrent down the side of Proffit Mountain equivalent to a flood-swollen Missouri River, according to a U.S. Geological Survey (USGS) study released today.

While the devastation caused by the pre-dawn breach was immediately visible, the USGS report, funded by the Missouri Department of Natural Resources, was the first effort to scientifically quantify the size and power of the subsequent flood.

The breach, which occurred shortly after 5 a.m. Dec. 14, 2005, tore out a 680-foot wide section of the upper reservoir and sent an estimated 1.3 billion gallons of water rushing down the western side of the mountain, emptying into the flood plain of East Fork of the Black River. Flood waters from the upper reservoir flowed downstream through Johnson's Shut-Ins State Park and into the lower reservoir of the East Fork of the Black River.

At its peak, the water rushed down the side of the mountain at a rate of 289,000 cubic-feet per second, roughly equal to the flow of the Missouri River at three to five feet over flood stage. High water marks along the water's route down the mountain indicated that it reached depths of 50 feet or more. The subsequent flood of the East Fork of the Black River was approximately four times larger than a 100-year flood, said report author Paul Rydlund.

"During a 100-year flood, water would flow through the river at 21,900 cubic feet per second," Rydlund said. "At the peak flow of this release, it was coming through at 95,000 cubic feet per second."

Models used to route the flood wave from the breach of the upper reservoir to the spillway of the lower reservoir estimated flood wave arrival time between 5.5 and 6 minutes to enter the floodplain of the East Fork Black River, and 29 minutes to begin filling the lower reservoir.

"The movement of water down Proffit Mountain reached a speed as fast as 51 feet per second (35 miles per hour)," said Rydlund.

In addition to the destruction of natural resources, the event did significant damage to the park's facilities and infrastructure. It destroyed the home of the park superintendent, injuring him and his family. "The wall of water coming into contact with the park superintendent's residence was approximately 10 to 20 feet high," Rydlund said.

Quantitative estimates of debris movement were recorded and documented as sand/gravel and woody debris. Using a GIS technique, an estimated 180 acres of timber were affected along the western side of Proffit Mountain to a location in the park.

The USGS serves the nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life.

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Editors: The report, "Peak Discharge, Flood Profile, Flood Inundation and Debris Movement Accompanying the Failure of the Upper Reservoir at the Taum Sauk Pump Storage Facility near Lesterville, Missouri, 2006-5284" is available at http://pubs.usgs.gov/sir/2006/5284/.