The Lower Columbia River Steelhead DPS includes all populations of steelhead in the Columbia River and its tributaries in Washington and Oregon, from the mouth of the Columbia up to and including the Big White Salmon and Hood Rivers. It also includes the Willamette River to Willamette Falls.
The State of Oregon only monitors populations occurring in Oregon. There are nine recognized independent populations of winter steelhead in the Lower Columbia DPS, however data are only available for three: The Clackamas and Sandy Rivers in the Cascade Stratum, and the Hood River in the Gorge Stratum.
Statistical surveys were conducted in the Clackamas and Sandy River basins in the Cascade Stratum in 2006 and 2007. A long-term statistical monitoring design for the entire ESU begins in 2012. Counts at Powerdale Dam on the Hood River are available from 1991 to 2007, after which the dam was removed.