SCH Number 2019129049
- Log Cabin and Our House Diversion Dams Sediment Management Plan
- The purpose of the Plan is to prescribe procedures and guidelines for the management of sediment behind Log Cabin Diversion Dam and Our House Diversion Dam. The objectives of the Plan are twofold: 1) to provide for dam safety and proper functioning of FERC Project facilities, especially the fish release and low level outlet valves; and 2) to maintain the health of the aquatic environment downstream of the dams by allowing the passage of sediments that occur behind the dams. The Plan is located on TNF, YCWA, and private lands in Nevada, Sierra and Yuba counties. Log Cabin Diversion Dam is located in Yuba County, and Our House Diversion Dam is located in Nevada and Sierra counties. Sediment management at both Log Cabin and Our House diversion dams includes five components: 1) maintenance of minimum pools; 2) passage of sediment; 3) removal of outlet blockages; 4) planned mechanical removal of sediment, when needed; and 5) emergency removal of sediment. The main features of the proposed project area are: Log Cabin Diversion Dam and Impoundment (3.57 acres); Our House Diversion Dam and Impoundment (10.10 acres); Disposal Site 1 (9.51 acres); Disposal Site 2 (11.6 acres); Disposal Site 3 (80 acres), Celestial Valley Mitigation Site (2.5 acres), Log Cabin Temporary Laydown area (0.34 acre), Our House Temporary Laydown area (0.28 acre), and access roads. Sediment passage would be done between October 31 and March 21, in the years when it is implemented. Sediment removal would be conducted in low flow conditions, September 15 through November 15 in a normal year, during years when it is necessary.
2 documents in project