WENATCHEE- The Chelan PUD determined the cause of a small oil sheen detected on the downriver side of Rock Island Dam’s Powerhouse 1 on March 29. Work in preparation for rehabilitation of one of the turbine units resulted in a small amount of residual oil being released from the unit.
Chelan PUD employees acted quickly Thursday around 2 p.m. when the small sheen was detected near the left bank (Douglas County side) of the Columbia River. Absorbent containment booms were put into place and an oil skimmer was used. Two additional units were shut down to help with the source investigation.
Early this morning, the two units were restarted to test for oil dispersion. No evidence of oil appeared in the dam’s tailrace, according to the Chelan PUD in a press release.
The two units will be put back into service as soon as the booms are removed. The unit where the oil originated will remain out of service until rehabilitation work is completed.
Washington State Dept. of Ecology spill prevention staff were notified as soon as the sheen appeared and have been on-site Thursday and today. They have finished their investigation and the cleanup is complete.