Planning and Research, Office of
(Office of Planning and Research)
Wallace Creek Fish Passage Enhancement Project
NOE - Notice of Exemption
The Project is being undertaken as a result of the National Marine Fisheries Service's 2008 Biological Opinion for Water Supply, Flood Control Operations, and Channel Maintenance conducted by the U.S. Army Corps of Engineers, the Sonoma County Water Agency, and the Mendocino County Russian River Flood Control and Water Conservation District in the Russian River Watershed (Biological Opinion). As part of the requirements in the Biological Opinion's Reasonable and Prudent Alternative section, the Sonoma County Water Agency is proposing to retrofit an existing box culvert on Wallace creek below Mill Creek Road in order to enhance passage for salmonids through the structure. The existing culvert consists of two side by side concrete box culverts that both have flat, smooth bottoms that result in shallow flows through the culvert that impedes the passage of salmonids under certain stream flows. The downstream outlet of the culvert has elevation drop that also limits salmonid passage under certain stream flows. The proposed project consists of retro-fitting one of the two culverts by excavating out the bottom of the culvert and installing concrete weirs to create pools through the culvert and connect the culvert to the downstream pool. Connecting to the downstream pool has a bedrock bottom which would require chipping out the rock in order to deepen the pool. Issuance of a Streambed Alteration Agreement No. 1600-2011-0218-R3 is pursuant to Fish and Game Code Section 1602.