HUDSON SPILLWAY MODIFICATION - ENG26-00006

This permit is to approve a Grading permit for the proposed Hudson Spillway Modification, the project has already obtained a Lake and Stream bed Alteration agreement from the California Department of Fish and Wildlife; Agreement number 1600-2020-0108-R3, pursuant to Section 1602 of the Fish and Game Code to Hudsonia. The project is limited to decommissioning an existing approximately 120-foot long, 13-foot-wide concrete spillway of an on-stream reservoir (reservoir) and constructing a new approximately 215-foot long, 13-foot-wide concrete spillway. The California Division of Safety of Dams is requiring that the project relocate the spillway off the face of the earthen dam for safety reasons. The new spillway inlet will be relocated approximately 175 feet to the west, and the spillway will outlet into the unnamed tributary at approximately the same location as the existing spillway. At the new spillway outlet, an approximately 30-foot diameter, 2,115 square-foot stilling basins composed of 245 cubic yards of 8-inch diameter rock riprap will be constructed within the stream channel to prevent scour during reservoir spills. At the top of the dam face and at the inlet to the new spillway, an approximately 13-foot long, 16-foot-wide steel bridge will be constructed across the spillway to allow for vehicular access. At the south end of the stilling basin, an approximately 36-foot long, 14-foot wide free-span steel bridge (i.e., Residential Bridge) with concrete abutments located outside top of bank will be constructed. Additionally, 155 cubic yards of 8- inch diameter rock riprap will be placed in the channel and along the banks underneath the bridge to prevent channel erosion. Project will utilize Best Management Practices and erosion control measures.