Upper Butte Basin Wildlife Area - Llano Seco Unit Enhancement (Lake or Streambed Alteration Agreement No. 1600-2016-0196-R2)

Upper Butte Basin Wildlife Area - Llano Seco Unit Enhancement (Lake or Streambed Alteration Agreement No. 1600-2016-0196-R2)

CDFW has executed Lake and Streambed Alteration Agreement No. 1600-2016-0196-R2, pursuant to section 1602 of the Fish and Game Code to the project Applicant, Tim Hermansen, CDFW. Project's purpose is to improve water use efficiency and management capabilities. Specifically, it will provide the water control infrastructure necessary to capture irrigation runoff for agricultural lands and wetlands on Llano Seco Ranch (LSR) for reuse to support seasonally management wetlands and riparian habitat on Llano Seco Unit. Project specifics include: an existing earthen structure will be replaced with a hardened spillway and water control structure. Existing vegetation will be stripped from the proposed spillway footprint. Soil to build the spillway will be borrowed from nearby locations to the northeast and southeast of the spillway. A water control structure will be installed in the spillway to provide improved water management capabilities. This structure will allow management flexibility to reuse agricultural runoff water and allow natural flows downstream during storm events and outside of the irrigation season. Rock rip rap will be placed around the water control structure outfall. Articulated concrete block mats or rock rip rap will be installed on the spillway to provide erosion protection. An overflow section was incorporated into the spillway design to account for flood water overtopping. The spillway will be approx. 140 feet long with a bottom width of 80 feet. The upstream side slope will be approx. 5:1 and the downstream side slope will be approx. 10:1. This construction will disturb approx. 0.08 acres of wetlands/waters. Approx. 500 cubic yards of soil, gravel, rip-rap and concrete block mats will be placed on the structure to prevent scouring and erosion. Two temporary coffer dams will be constructed, one upstream and one downstream of the proposed spillway location. Both temporary coffer dams will be removed after construction of the spillway is completed. The temporary upstream coffer dam will temporarily disturb 0.05 acres of wetlands/waters. it will be 110 feet long and require approx. 264 cubic yards of material. The temporary downstream coffer dam will temporary disturb 0.03 acres of wetlands/waters. It will be 75 feet long and require approx. 130 cubic yards of material. Both coffer dams will be removed once construction of the spillway is complete. The material used to construct the coffer dams will be spread back into the areas from which it was excavated. The material required to construct the spillway and the coffer dams will be excavated from nearby borrow areas. The vegetative cover will be stripped from the borrow areas and placed in a pile. This material will be spread over the cut area after construction is complete. An average of 0.6 feet, with a range of 0.3 to 0.9 feet, will be cut off the top of both borrow areas. Both borrow areas are located in fallow agricultural fields that were disturbed in the past by agricultural operations and consist of upland habitats. Project activities will not reach below or beyond the limits of prior land disturbance.

Chico

Butte, Glenn