Avista monitors oil spill location

NOXON, Mont., — Avista will continue to maintain deployed booms and monitor conditions of the Clark  Fork River in North Idaho and Western Montana over the next several days, as assessment and clean-up of a 1,250-gallon oil spill continues.

Avista plans to resume normal operations at Noxon Rapids and Cabinet Gorge Hydroelectric Projects early next week.

“There have been no observable impacts to fish or wildlife from this incident,” Bruce Howard, director of environmental affairs for Avista, said. “Also, we have no indications that there is any threat to water supplies or that the incident will cause long-term impacts to the aquatic ecosystem of the lower Clark Fork River or Lake Pend Oreille.”

Avista will continue working with emergency officials and environmental agencies to actively monitor and mitigate any environmental impacts to the river and shoreline.

The spill was discovered at Avista’s Noxon Rapids Hydroelectric Project Thursday, Feb. 26, 2009. Avista immediately implemented emergency spill procedures and began working with local, state and federal agencies to assess the situation and implement a clean-up plan.

Preliminary indications were that ice that had built up on the face of the dam fell off and broke a pressure gauge on the valve of a pipe carrying transformer oil, causing oil to spill onto the transformer deck. The deck contains storm water drains and oil was released from one of these drains into the river.

The river was inspected from the water and air for areas of visible oil Friday and throughout the weekend. The oil, a lightweight mineral oil used to cool transformers, was initially visible as a fine sheen on the surface of the water in an area upstream from Heron Bridge in Montana.

Avista shut down operations at Noxon for several hours Friday and minimized flows at Cabinet Gorge, then resumed operating one or two units at a time through the weekend in an effort to keep water levels consistent and calm and contain the oil to the area upstream of Cabinet Gorge. The area where oil was spilled at the dam itself was cleaned and some oil was recovered in that process. Normal generation should resume by March 9.

On Friday and Saturday, three curtain and absorbent oil booms were placed in the water near the Heron Bridge where the oil sheen could be seen, and upstream from Cabinet Gorge dam. By Saturday, the situation was downgraded from emergency status and Avista and a private spill contractor continued to maintain and monitor the booms through Sunday and into Monday. There is no indication that the sheen moved further downstream or accumulated on the shoreline.

Contractors are continuing to assess the water and shoreline from boats. Absorbent booms and materials will be used in any areas indicating the presence of oil, and booms will be maintained in place for at least the rest of the week.