Biggs-West Gridley Water District
The Gray Lodge Wildlife Area (Gray Lodge), located 65 miles north of Sacramento in the eastern Sacramento Valley, is owned and managed by the California Department of Fish and Game (CDFG) but depends on Biggs-West Gridley Water District (District) for most of its water supply. Through an agreement with the Bureau of Reclamation (Reclamation) and other state agencies, the District conveys project water to the seasonal wetlands and irrigated pasture and crop land of Gray Lodge through a series of District-maintained canals and ditches to three delivery points at the boundary of Gray Lodge.
In 1992, Congress passed the Central Valley Project Improvement Act (CVPIA). Under CVPIA, Reclamation is required to provide additional water to various refuges, including Gray Lodge. The scope of this project is to design and construct the improvements necessary to convey a water supply in excess of Biggs-West Gridley Water District’s current annual allocation to Gray Lodge (approximately 8,600 acre-feet). It is important to note, that the District is not using any of its own water supply for this project.
To get the necessary volume through the existing system, the channel will need to be improved and structures will need to be upgraded and / or replaced. Increasing the capacity of the District’s water conveyance system will require the replacement of nearly 35 structures including checks, siphons, weirs, culverts, and bridges for railroad, county, and road crossings. Additionally, some of the 20 miles of canals and laterals will be raised and/or widened.
Project concerns include increased seepage to adjacent farm lands, impacts to right-of-way due to raising and widening of canal embankments, embankment stability, cost and availability of borrow material, and impacts to wetlands and the Giant Garter Snake. During our analysis it was determined that with the in-line canal restrictions removed and the canals operated at normal flow depths at design flow, the new design water surface levels could remain the same as under current operations, thereby minimizing project concerns.
Dahl Consultants served as Project Manager and provided design support in addition to seepage evaluation, right-of-way activities, and landowner relations.