Under regular operations, water is released from San Luis Reservoir to the State Water Project (SWP), the Central Valley Project (CVP), and the San Felipe Division (SFD) of the CVP.
- As the San Luis Reservoir is drawn down during the summer and into the late fall (when water supplies are needed most), a thick layer of algae (as much as 35 feet thick) grows on the surface.
- As the water level lowers, this algae gets captured by SFD intakes.
- The algae degrades water quality and makes water more difficult to treat.
- As a result, San Felipe Division deliveries can be interrupted when the reservoir falls below 300,000 acre-feet.
- These delivery interruptions are critical because the San Luis Reservoir is the only CVP water source that SFD contractors can access.
Potential effects of these issues include:
- Interruption of water deliveries to domestic, industrial, and agricultural users
- Interruption of water deliveries used to replenish groundwater supplies
- Blockage of agricultural irrigation systems
- Reduced ability to treat water effectively
- Increased water treatment costs
- Taste and odor problems
Reclamation, along with the San Luis & Delta-Mendota Water Authority (Authority) and Santa Clara Valley Water District (SCVWD), is preparing a Feasibility Study for the San Luis Reservoir Low Point Improvement Project (Project).
In Public Law (PL) 108 361, Section 103(f)(1)(A), the Secretary of the Interior was authorized to conduct feasibility studies of San Luis Reservoir.
The San Luis Reservoir Low Point Improvement Project is proposed to maintain a high quality, reliable, and cost-effective water supply for SCVWD and other contractors of the Bureau of Reclamation's San Felipe Division to ensure that these contractors receive their annual Central Valley Project contract allocations at the time and at the level of quality needed to meet water supply commitments.
Optimize the water supply benefits of San Luis Reservoir while reducing additional risks to water users by:
- Avoiding supply interruptions when water is needed by increasing the certainty of meeting the requested delivery schedule throughout the year to south-of-Delta contractors dependent on San Luis Reservoir.
- Increasing the reliability and quantity of yearly allocations to south-of-Delta contractors dependent on San Luis Reservoir.
The San Luis Low Point Improvement Project may provide opportunities for ecosystem restoration and recreation.
The study area includes San Luis Reservoir and the service area of the San Felipe Division. The study area encompasses Santa Clara counties. San Luis Reservoir, part of the San Luis Unit of the West San Joaquin Division, is located near Los Banos in Merced County about 80 miles southeast of San Francisco.
The authorization directed that for San Luis Reservoir, “Funds may be expended for feasibility studies, evaluation, and implementation for the San Luis Reservoir Low Point improvement project, except that Federal participation in any construction of an expanded Pacheco Reservoir shall be subjected to future congressional authorization.”
This authorization is under the CALFED Bay-Delta Program, California Water Security and Environmental Enhancement Act (CALFED Bay-Delta Authorization Act). It is included in a section that provides New and Expanded Authorization for Federal Agencies for involvement in conveyance projects.