The San Luis Reservoir near Los Banos could see its storage capacity grow by over 6 percent, according to a new study on the feasibility of expanding the lake released by the U.S. Bureau of Reclamation.
According to the draft report, a 20 foot increase in the height of the B.F. Sisk dam would result in 130,000 acre feet of additional water storage capacity. For comparison, that increase would be equal to about a quarter of the total capacity of Friant Dam near Fresno.
San Luis Reservoir currently has a maximum capacity of just over 2 million acre feet. Officials estimate construction on the expansion project would cost around $360 million.
In addition to providing extra water storage for the federal Central Valley Project and California's State Water Project, the proposed construction would also include seismic improvements to the dam. An earlier report by the Bureau identified several nearby active faults that present a "significant seismic risk" to the nearly 50-year-old dam. The improvements would be in the form of "stability berms" constructed at the base of the dam.
If such seismic improvements are not made, the report's authors say water officials could be forced to lower the maximum water level by as much as 50 feet to "reduce the risk" to within current Bureau guidelines.
The draft study comes as California deals with the possibility of a third consecutive dry year, plus pumping restrictions in the delta that have reduced the level of the lake to just 25 percent of its capacity (42 percent of the average for November).
The draft report also outlines several other possibilities involving the lake, including a proposal to establish a "utility-scale" solar power facility at the site that could generate between 20 and 100 megawatts of electricity, and efforts to improve water quality for users in the Santa Clara Valley.