We invite you to review and comment on the draft periodic review report for the Spokane River Upriver Dam and Donkey Island site.
The Spokane River drains more than 4,900 square miles in Washington and Idaho. Industries and municipal wastewater treatment plants located within the watershed upstream of the site have discharged PCBs (polychlorinated biphenyls), creating contaminated deposits above Upriver Dam and in a channel on the northern side of Donkey Island. The two deposits were investigated and cleaned up from 2006 to 2007. The Upriver Dam deposit was covered with a protective cap, and the Donkey Island deposit was excavated, backfilled with clean sediment, and replanted.
We visited the site Aug. 13, 2021, and used data from sediment samples taken in 2008, 2010, and 2020 to determine the remedies are still effective. We are recommending further sampling and monitoring of the Upriver Dam cap because 2020 sampling results indicated PCBs are beginning to move upwards through the cap, but have not broken through. In addition, surficial sediments deposited on the cap contained elevated PCBs and heavy metals, meaning upstream contaminants are continuing to deposit at the site. The additional samples would show how much has resurfaced. Monitoring is planned to occur in 2025 to inform the next periodic review.
We will review comments received during the comment period and make recommendations for suggested changes. The periodic review will become final if no significant changes are made. An additional public comment period will be held if significant changes are made.
We will hold an online public meeting if 10 or more people request one.
About periodic reviews
We conduct a periodic review at least every five years at cleanup sites where some contamination remains, as required by the Model Toxics Control Act (MTCA). The purposes of the review are to evaluate site conditions and to ensure continued protection of human health and the environment.
This is the second periodic review for this cleanup site.