The National Marine Fisheries Service issued a Biological Opinion in 2008 requiring SCWA to enhance habitat and promote the recovery of these endangered and threatened fish species to mitigate for SCWA water supply management impacts.
Continuous high flow releases from Lake Sonoma to Dry Creek in the summer and fall provide the vital water supply needs of over 600,000 consumers in Sonoma and Marin counties but adversely affect juvenile rearing habitat.
In addition, water management impacts associated with flood control activities by the U.S. Army Corps of Engineers (USACE), and historical land use impacts associated with gravel mining, grazing, and agricultural land uses have cumulatively altered the geomorphic characteristics and hydrologic regime of Dry Creek to the detriment of aquatic habitat.
Working closely with the USACE, SCWA and resource agencies, our team is preparing enhancement plans, starting with initial concept plans through all phases of engineering design to a complete set of 100% construction drawings. Cardno will also be providing construction management for implementation of the habitat enhancements.
Workshops are held with the resource agencies and land-owners at key milestones during each major step of the project. Key habitat enhancements include developing side channels, low velocity alcoves, a more sinuous planform with meander bends holding deep pools, engineered large wood jams, and grading to reconnect Dry Creek with former floodplain surfaces, which are now disconnected within an incised channel corridor. These enhancements are designed to provide juvenile salmonoid rearing and high-flow refuge habitat that will allow SCWA to continue to release water into Dry Creek for delivery to community water supplies and to improve conditions during prolonged high flow flood control releases by the USACE.