The U. S. Army Corps of Engineers built Cougar Dam on the South Fork McKenzie River in the 1960s. Biologists estimate the habitat above the dam once supported more than 4,000 returning adult spring Chinook. Original construction included both adult and juvenile fish passage facilities to help move fish past the dam. However, due to the dam’s impact on downstream river temperatures, adult fish no longer migrated to its base. The Corps abandoned the original adult and juvenile fish passage facilities because they proved to be ineffective.
In combination with the Cougar Dam Temperature Control Facility, this new $10.4 million collection facility supports a complete fish lifecycle over long stretches of the South Fork McKenzie River by moving adult fish to high quality spawning habitat above the dam. Fisheries biologists believe this will substantially support recovery of endangered fish populations in this Willamette River sub-basin.