With precipitation from the last two storms falling throughout Northern California, it has been a much needed boost to reservoir levels throughout the region, which will help with water supplies for next year. In the past week, Shasta Reservoir on the Sacramento River has risen over 24 feet, the Feather River’s Oroville Reservoir more than 19 feet, New Bullards Bar Reservoir on the Yuba River almost 10 feet, Indian Valley Reservoir on Cache Creek almost 14 feet and the American River’s Folsom Reservoir almost eight feet. During the first two weeks of December, the increases in storage are even more impressive. Total increases in reservoir elevations since December 1 are as follows: almost 32 feet at Shasta, 36 feet at Oroville, more than 25 feet at New Bullards Bar, almost 19 feet at Indian Valley and more than 15 feet at Folsom.
These rapid increases in reservoir elevations during the first two weeks of this month have resulted in equally impressive additions in overall surface water storage. Shasta increased by 395,713 acre-feet, Oroville 238,202 acre-feet, New Bullards Bar 43,156 acre-feet, Indian Valley 17,171 acre feet and Folsom 90,616 acre-feet.
As good as this news is, we also need to recognize the missed opportunity to capture even more water that is falling below the existing dams. In particular, the addition of Sites Reservoir, which would be an off-stream reservoir filled by existing diversions on the Sacramento River, would allow for water collecting in the Sacramento River below Shasta Dam to be stored until it is needed next year. Currently, there are no opportunities to store this sizable amount of water. During the most recent storm, flows at Bend Bridge, which is upstream of the two existing diversions that would be used to fill Sites, peaked at 139,489 cubic-feet per second (cfs), while Shasta Reservoir was only releasing 296 cfs. While this is an extreme example of the considerable flows that are currently not being captured, even with more modest flows Sites could still collect more than 500,000 acre-feet in new storage in two months with the existing diversions on the Sacramento River. That is enough water to meet the needs of one million households, or four million people (more than reside in the City of Los Angeles) for one year. This water could then be held until it is needed next year to provide benefits in the Sacramento Valley for all uses, including salmon, birds, farms and rural communities.