Benbow Dam Removal and Lake Restoration, Eureka, CA
Client: State of California Department of Parks and Recreation
Questa prepared plans for the removal of the Benbow Recreational Area Dam. This dam, built in the early 1930s, was used as a seasonal structure that impounded the Eel River in Northern California during the summertime months. The seasonal installation of steel I-beams and flashboards was halted in 2007 due to various environmental concerns and operational challenges faced by State Parks. Federal and State resource agencies expressed concerns about the impact of Benbow Dam on anadromous fish in the watershed and accelerated wind-driven erosion and sedimentation caused by Benbow Lake.
Questa completed extensive hydrologic/hydraulic analysis, including scour analysis, to ensure that dam removal, lake grading and subsequent stream incision does not undermine three California Highway 101 bridge crossings. Final dam demolition plans were developed that specify access routes, staging areas, pre- and post-project biologic mitigation and monitoring, river diversion phases, concrete removal and recycling plans, as well final channel grading and bank stabilization techniques. Work will involve removal of 13,000 CY of concrete, two stream diversions, and in-channel grading and erosion control.