fish passage improvement 2011
shearer dam removal
The Shearer Dam was also originally a push-up dam, then later a wooden crib dam and finally the concrete structure that was removed, built in 1956. The dam’s purpose was to divert Calapooia River flows to the Mills via a human-dug channel (mill race).
The Shearer Dam was located on the Calapooia River at approximately RM 23. The dam was a 40-ft wide concrete structure, 5 feet in height from the scour apron to the crest of the dam. The crest of the dam was 7.1 feet higher than the water level in the downstream scour pool under stagnant conditions. The weir and pool fishway was comprised of three pools 6-ft wide by 9.5 ft long by 3-ft depth.
Problems Associated with the Shearer Dam Included:
1
The dam had a fishway along the west bank of the dam which did not meet current fish passage criteria and did not provide passage during low flow conditions, due to the presence of rock ballast at the outlet that extends above the water level.
2
Additionally, the fishway pool weirs were not appropriately sized, allow too much water through them, thus creating adverse hydraulic conditions for fish passage. Under stagnant conditions this was a barrier to fish. At low stream flows the flow depth may have been too shallow for fish to traverse and jump into the fishway entrance.
Along with Sodom dam, Shearer dam had been known fish passage problems for decades, but because of their complexity and lack of a simple, inexpensive solution, nothing had been done to address them until recently. Between 2007 and 2011, the Calapooia Watershed Council (CWC), with the support from State parks and an active Technical Team composed of local, state and federal natural resource officials and local landowners, built the relationships and did the outreach necessary to obtain stakeholder support for removal of Sodom and Shearer Dams in 2011 and continued maintenance of the project site in the coming few years.