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Update on the California Drought: February 1 – March 6, 2017
From the Pacific Institute’s California Drought Response Team
Worst of California Drought Over, But Impacts Linger
Despite a significant improvement in drought conditions, impacts remain. The most recent NASA data reveal that parts of the San Joaquin Valley have been sinking due to groundwater depletion. Between May 2015 and September 2016, significant subsidence was measured in two areas near the towns of Chowchilla, south of Merced, and Corcoran, north of Bakersfield. These “bowls” cover hundreds of square miles, affecting aqueducts and flood control infrastructure. Scientists found that subsidence for some areas in the San Joaquin Valley slowed during the winter of 2015-2016, when rainfall matched crop water needs.
Estimates of adult fall-run Chinook salmon swimming off the coast of California, which serve as a basis for the 2017 fishing allowances, suggest another bleak salmon fishing season for California fishermen. Preseason estimates of the Klamath River fall-run Chinook fell by 62% from 142,200 fish in 2016 to 54,200 in 2017. Sacramento River fall-run Chinook estimates fell from about 300,000 fish in 2016 to 230,000 in 2017. These declines are likely related to the drought’s lingering impacts, as adult salmon returning to California rivers were hatched two to four years ago, when river and ocean conditions were poor.
In Other News
- The State Water Board has extended its existing water conservation regulations, prohibiting wasteful water use practices, such as watering lawns after it rains, and setting a conservation mandate for water suppliers projected to face shortages if the drought continues for three more years. A more thorough review of the state’s water supply conditions is being conducted and a reconsideration of the conservation regulations is planned for May 2017.
- New water conservation data reflect continued statewide water saving efforts despite recent rains. Water savings in December 2016 was 20.6% compared to the December 2013 production baseline, 11% higher than December 2015 savings. In all, from June 2015 through December 2016, 2.4 million acre-feet of water were conserved.
- Work on the Oroville Dam continues after the eroded main spillway prompted a two-day evacuation of 188,000 nearby residents. The worst of the crisis seems to be over, unless more severe storms hit Northern California. Last week, the Department of Water Resources halted water releases and shut down the main spillway to remove debris washed into the river channel below and allow the hydroelectric turbines at the base of the dam to resume operation. However, the reduction of the dam’s outflows caused the water level in the Feather River to drop rapidly, resulting in riverbank erosion. Additionally, the reduction of flow has left fall-run Chinook salmon, steelhead trout, and other fish trapped in riverbed pools, prompting rescue operations.
- The US Bureau of Reclamation has announced a full initial allocation for Central Valley Project (CVP) contractors receiving water from the Folsom, New Melones, and Millerton reservoirs, which have unusually high projected runoff from snowmelt. Initial allocation for the remaining water service contractors, predominantly agricultural water districts, will be available in mid-to-late March. The allocation is subject to change based on water conditions.
- On February 2, the second manual snow survey at Phillips Station, near South Lake Tahoe, found a snow water equivalence of 28.1 inches, almost 10 inches higher than the average (or 173% of normal) for this date and about five times higher than the previous month’s measurement. Snow water equivalence is the theoretical depth of water if all snowpack were to melt completely. The California snowpack typically supplies about 30% of the state’s water needs.
- As concern over meeting peak water demand in the summer looms, the City of Santa Barbara is set to restart water production at its mothballed desalination plant in April 2017. The plant, closed since 1992, has a small production capacity of 3,125 acre-feet of water, but could be expanded to produce up to 10,000 acre-feet per year. The capital costs for reactivation are estimated at $70 million with an annual operating and maintenance cost of about $4.1 million at full production, or $1.4 million in non-operation or standby mode.
- The San Jose Water Company, which serves the needs of one million people in San Jose and neighboring communities, has dropped its drought surcharges. The private water company is the last large water supplier in the Bay Area to suspend fines and penalties for excessive water use.
California Drought Status
Drought conditions are continuing to improve significantly in California. Precipitation in recent weeks and months has resulted in the removal of the “extreme” and “exceptional” drought designations from the state’s drought monitor. Currently, about 9% of the state is experiencing moderate to severe drought conditions compared to about 50% last month. Over 70% of the state is now identified as being drought-free.
Since the beginning of the water year on October 1, 2016, cumulative precipitation in California’s three key hydrologic regions has been far above the long-term average. As of March 6, 2017, the Northern Sierra and San Joaquin regions had received 78 inches and 62 inches of precipitation, respectively. They are on track to receive more precipitation this water year than in the 1982-1983 water year, the wettest on record. While cumulative precipitation in the Tulare Basin region (currently at 42 inches) is no longer on track to match the region’s wettest recorded water year in 1968-1969, its water level is 205% above average for this date.
California’s snowpack conditions are excellent. As of March 6, total snowpack was about 180% of normal, and 167% of the April 1 average (when snowpack is expected to be at its peak).
The water levels in California’s major reservoirs (representing 27.3 million acre-feet of storage) have increased by 11 percentage points over the past month, and now represent 76% of the statewide capacity. Current storage levels represent 115% of the historical average for this time of year, about 5 percentage points higher than last month. As of March 6, conditions at selected reservoirs were as follows:
- The water level at Lake Shasta was at 102% of the historical average for this time of year. Lake Oroville and Folsom Lake were at 115% and 68% of the historical average, respectively.
- The water level at the New Melones Reservoir, another major reservoir with a 2.4 million acre-feet capacity, was at 110% of the historical average for this time of year.
- The water level at the San Luis Reservoir was at 115% of the historical average for this time of year.
- Lake Cachuma, which supplies water to the City of Santa Barbara and other urban areas in Southern California, remains well below average. Over January, the water level increased from 12% to 45% of capacity. As of March 6, the water level was at 54% of the historical average for this time of year.
We will resume updates when the 2017 wildfire season begins (typically in May).
Statewide hydroelectric power generation improved considerably in December 2016. Production was about 2,300,000 MWh, an increase of 176% over last year’s December production of 840,000 MWh and 12% over the 2001-2011 average for the same month. Total hydropower production for 2016 was nearly 29,000,000 MWh, the highest since the drought began in 2012, but still 14% below the average annual production for the period of 2001 to 2011.
Groundwater conditions have likely improved as a result of recent storms, but comprehensive data are updated infrequently.
The most recent data on groundwater conditions are based on measurements taken in spring 2016. Maps of spring and fall groundwater level changes can be found here. Parts of the Tulare Lake, the South Coast, and the Colorado River hydrologic regions experienced groundwater declines of more than 100 feet between fall 2011 and fall 2015.