Biologists begin assessing damage from reservoir failure

Much work remains to be done before biologists know how soon-and how fully-fish and wildlife will recover.

LESTERVILLE, Mo.-Much of the damage from a reservoir failure in Reynolds County late last year is obvious. The flood obliterated a campground and destroyed buildings at Johnson’s Shut-Ins State Park. It smothered a natural area with muck and muddied a reservoir and two rivers. But more subtle effects will linger long after facilities are rebuilt, water is cleared and debris is removed. Assessing the biological effects of the calamity is the job of the Missouri Department of Conservation, along with other agencies.

The flood occurred in the early morning hours of Dec. 14, when the upper reservoir of AmerenUE’s Taum Sauk hydroelectric power plant failed, releasing more than a billion gallons of water into the East Fork of the BlackRiver. No human lives were lost, but the flood changed the landscape and the stream, affecting plants and animals.

The hydroelectric plant included an upper reservoir atop Profitt Mountain and a larger lower reservoir on the river’s East Fork. Johnson’s Shut-Ins State Park lies between the two reservoirs. As the water rushed downhill, it uprooted trees and scraped parts of the mountain down to bare, volcanic rock. By the time it reached the park, the torrent carried tons of boulders, gravel and mud and hundreds of trees.

Entering the Black River’s East Fork at the north end of the state park, the water sloshed across the valley, obliterating an empty campground and almost everything else in its path. The once-forested flood plain above and below Highway N was blanketed with natural and manmade debris, including pieces of the upper reservoir’s concrete dam and heavy plastic liner.

As it cascaded through the gorge from which Johnson’s Shut-Ins State Park gets its name, the abrasive mix of water and debris scoured away trees far up the rock walls. After leaving the shut-ins the surge of water and sediment quickly filled all of Lower Taum Sauk Lake’s extra capacity. The dam held, in spite of being overtopped. That prevented severe flooding downstream, but muddy water fouled the East Fork and the Black River far downstream.

In the aftermath of the flood, Conservation Department biologists have been called on to assess its impact on nature, especially fish and other aquatic life. In a lucky coincidence, the agency already had been conducting biological surveys on the East Fork and Black River in preparation for the renewal of AmerenUE’s federal license for the Taum Sauk power facility. Having pre-flood biological data will permit better evaluation of the flood’s effects.

Conservation Department workers have started gathering information on possible flood impacts, including:

--Aquatic habitat loss.
--Fish numbers and variety.
--Tree losses.
--Changed stream-flow patterns.
--Soil erosion.

Resource Scientist Del Lobb said most of the fish and wildlife living in and along the East Fork upstream from the lower reservoir probably were either killed or washed downstream. He said one goal of sampling is to determine how quickly fish populations recover. One interesting early finding is the discovery of madtoms, tiny catfish that normally are found only in streams, in the lower reservoir.

Flood water washed over the lower reservoir’s dam, discharging a large amount of silt and sand into the Black River. The lower reservoir remained muddy and continued to discharge muddy water into the Black River. AmerenUE used chemicals to settle sediment suspended in the reservoir water. The treatment, which also is used in municipal drinking-water supplies, is considered safe, and the effort cleared the reservoir’s water substantially. The Conservation Department and other agencies will monitor the long-term effectiveness of efforts to clear the water.

Johnson’s Shut-Ins State Park contains three natural areas-the shut-ins area itself, a glade and a moist area known as a fen. Johnson’s Shut-Ins Fen Natural Area, which harbors several rare and unusual plants, was smothered by mud and debris. State and federal agencies are working with consultants for AmerenUE who are removing the mud by hand in an attempt to save as many plants as possible. The calendar is on their side, as most of the plants are dormant in winter.

The park is closed to the public due to safety concerns while clean up and reconstruction take place. To let Missourians see the damage and ongoing restoration work, the Missouri Department of Natural Resources has created a gallery of dozens of aerial and ground-based photos at www.mostateparks.com/jshutins/pics_main.htm.

-Jim Low-

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