Hydrologic Conditions: Elsewhere in the Southwest, December 2015

Lake Oroville

Lake Oroville, the primary storage reservoir for the California State Water Project, continued to drop and ended November at 26% of its total capacity or 43% of the historical average for the date. Storage levels are above where they were at the same time last year, but are still below the historical low from the driest year on record (1976-1977). Capacity is increasing in December, but not at a slower pace than last year. (See chart)

Forecasters are predicting that El Niño is almost certain this winter, assigning high probabilities to the likelihood of wet conditions in Southern California, and expecting that wet conditions are more likely than dry conditions in Northern California. But snowpack levels and the impact of El Niño conditions on storage levels—the primary factors affecting DWR’s SWP allocation—remain in question. DWR announced an initial allocation of 10% on December 1^st and notes that the allocation could increase or decrease depending on the amount of precipitation received. (For an analysis of the initial allocation, see “California DWR Announces Initial SWP Allocation,” in this issue).