Tisha Calabres

State environmental officials Tuesday told TVA it may no longer sluice water in the Ocoee River without state approval.

The tightened rule came as regulators also added several new strings to a state demand of river restoration after a toxic sediment release Jan. 4.

The spill, TVA’s third in three weeks, occurred on a Sunday evening as power operators drew down water behind Ocoee Dam No. 3 to prepare for repairs on Ocoee Dam No. 2 downstream. TVA officials said they didn’t realize how much sediment, left over from decades of copper mining, had settled behind the No. 3 dam.

Some of the sediment, feared to contain PCBs and heavy metals, was drawn through the bottom gate as it emptied into the Olympic whitewater area of the river.

Black and foul-smelling sludge “overwhelmed the river” and the Olympic Whitewater Center area of the Ocoee “in some places more than three feet deep,” Tennessee Department of Environment and Conservation spokeswoman Tisha Calabrese-Benton said.

The sludge killed aquatic life that had begun to repopulate the Ocoee River, devoid of life for nearly 100 years because of the copper mining pollution, after mining was halted and a Superfund cleanup had begun.

Dam No. 3 had kept the new life separated from the toxins left in the sediment, state regulators and Cherokee National Forest officials said last week.

“It didn’t look like normal releases,” said Jim Herrig, a U.S. Forest Service biologist who took samples of the sludge.

Ms. Calabrese-Benton said the sample results are not completed yet.

“We also collected samples (Monday) to compare with the Forest Service results after a week had passed,” she said.

In Tuesday’s order, regulators told TVA officials that the utility’s newly required restoration plan, due Jan. 22, must include “at a minimum”:

n A demonstration component to show how toxic components in sediment and sludge deposits can be mobilized and removed while remaining under water

n A plan to limit public access to areas of sediment and sludge deposits until removal is complete.

n Monitoring and an annual survey of the damaged portion of the river to document the re-establishment of streamside and aquatic life. The monitoring must continue until restored life is comparable to what is found in healthy portions of the river.

TVA spokesman Jim Allen said the Ocoee spill and recovery “is not expected to affect the rafting season.”

Utility spokeswoman Barbara Martocci said TVA uses the bottom gate of Dam No. 3 to sluice water about 40 times a year, and now is investigating what caused the sediment to move down the river.