Black River may be clean by weekend

~ The river turned muddy after AmerenUE's Taum Sauk reservoir collapsed in December.

ST. LOUIS -- It's called the Black River, but the Southeast Missouri waterway has been more of a gunky brown since the reservoir at AmerenUE's Taum Sauk hydroelectric plant was breached in December.

On Wednesday, AmerenUE crews began a three-day process they said should have the water back to normal as early as this weekend.

"We expect to see the water clear up within approximately 12 to 18 hours" after the process concludes Friday, said Michael Menne, AmerenUE's vice president for environmental, safety and health.

The process involves the use of flocculates -- alums and a buffering agent that helps suspended particles to settle out of the water. The process, officials said, will remove clay from the river below the Taum Sauk reservoir.

AmerenUE officials said the process is safe -- alums are commonly used to treat drinking water. The Missouri Department of Natural Resources gave the go-ahead for the project earlier this month after determining the materials and the approach posed no threat to humans, wildlife or aquatic life, the DNR said.

"Anytime you talk about adding chemicals to water, you just want to make sure you're not impacting the water quality any more than it already has been," DNR spokeswoman Connie Patterson said.

AmerenUE crews are using a specially designed boat fitted with spray bars to apply alums evenly over a 60-foot-wide path in a lower reservoir that feeds into the Black River.

By cleaning the lower reservoir, the Black River will clear up as there will be less particles flowing into it, AmerenUE spokeswoman Susan Gallagher said.

Officials said the depth and speed of the boat are computer-monitored to ensure uniform dosage. Through the aid of a satellite global positioning system, a computer screen shows areas where the flocculates have been applied, AmerenUE said.

Scientists will test water in the reservoir and immediately downstream in the Black River for dissolved oxygen, alkalinity and turbidity, and will monitor the condition of aquatic life and other characteristics.

After the project, AmerenUE will lower the water level at the reservoir, releasing additional water that will further remove sediment deposited in the Black River, the company said.

The cause of the Dec. 14 reservoir failure remains under investigation, though AmerenUE officials have said the company accepts responsibility. The reservoir sits atop Proffit Mountain in Reynolds County, about 120 miles southwest of St. Louis.

The break caused more than 1 billion gallons of water to flood down the mountainside, causing significant damage to nearby Johnson's Shut-Ins State Park. Three young children of park superintendent Jerry Toops were hospitalized but later released.

The Taum Sauk plant was built in 1963 as a "pumped-storage" hydroelectric plant that stores water from the Black River in an upper reservoir, built atop the 1,590-foot mountain. Water is released from the upper reservoir, flowing down a mile-long tunnel inside the mountain and turning turbine-generators to produce electricity.

When power demand is low, the same turbines run in reverse, pumping water back up into the upper reservoir.

Southeast Missourian staff writer Kyle W. Morrison contributed to this report.