Clark Mountain Musings

Tuesday, December 20, 2005

USGS, UMR team assess damage at Taum Sauk

Monday, December 19, 2005 12:33 PM CST

Emitt C. Witt III, P.H.
Director, Mid-Continent Geographic Science Center

Lesterville, Mo. — The events of early Wednesday morning near
Lesterville were not nearly the scope of destruction resulting from
the past hurricane season; nevertheless, a tragedy and certainly one
of local significance.

On Dec. 14, sometime after 5 a.m., the upper reservoir at Taum Sauk
failed, allowing more than 1.5 billion gallons of water to careen
down a small drainage towards Johnson Shut-Ins State Park. The
mechanism for failure is under investigation, but what can be
determined from distant observation is that water spilled over the
sides of the impoundment possibly causing erosion of the outer
berms. This eventually weakened one segment of the structure to the
point of catastrophic failure.

A team of USGS and UMR scientists from the Natural Hazard Mitigation
Institute visited the site Dec. 15 to conduct a forensic analysis of
the failure and to map the affected area. While the power company
that owned the impoundment would not allow them access to the
location of the failure, the team was able to access the affected
area down gradient through Johnson Shut-Ins State Park. What the
team saw brought back memories of their recent work in New Orleans
and the Louisiana Peninsula.

The destruction at the site was incredible. All of the trees in the
path of the flowing water were stripped off the earth's surface.
What remained were large rocks and exposed bedrock surfaces. Where
the flowing water had reached fill material in the valley floor,
large scour holes were created. The large flowing debris piles
created by downed trees came to rest throughout the park and up
against the downstream side of the highway N bridge over the Black
River. The USGS stream gage located on that bridge was damaged by
the debris flow about the time the water moved through providing an
approximate time of when this event unfolded. While the Shut-Ins
Park received the most damage, private property located northwest of
the Park became a debris field for trees and a home destroyed by the
flowing water.

The team had limited access to the site, but were able to collect
data from the perimeter of the Park. These data will be used by
various agencies and the power company in the future. Images
collected can be viewed at
http://mcmcweb.er.usgs.gov/mcgsc

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