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About 50,000 cubic feet per second (cfs) of water is released from Shasta Dam on March 7 to make room in Shasta Lake for more rainwater and mountain runoff. The lake is the Central Valley Project's centerpiece reservoir.

Allocations inch upward as rain keeps falling

California, federal water projects update expected deliveries.

California's lead water agency has boosted anticipated deliveries to contractors to 70 percent of requested supplies, citing recent storms that have filled reservoirs to the brim and piled snow on Sierra Nevada mountaintops.

The Department of Water Resources today raised the State Water Project's allocation to its 29 member water agencies from the 35 percent announced last month.

“Just 10 weeks ago it looked like we may have been facing another dry year in California,” DWR Director Karla Nemeth says in a news release. “Fortunately, we’ve turned a corner and now it’s shaping up to be a great year for water supply. California’s hydrology varies year to year, which is why all Californians must work together to use water wisely.” 

The move follows the U.S. Bureau of Reclamation's announcement on March 15 that agricultural operations north of the Sacramento-San Joaquin River Delta will receive their full supplies while south-of-Delta ag contractors will receive 55 percent. The allocations were increased from the 70 percent and 35 percent, respectively, announced in February. The Friant Division's allocation remains at 100 percent for Class 1 water.

Both the state and federal allocations are assessed monthly, with the final allocation coming as late as May. The SWP's deliveries are already set to be double those of last year, when the final allocation was 35 percent.

"A 100 percent allocation is rare even in wet years due to Delta pumping restrictions to protect threatened and endangered fish species," DWR spokeswoman Maggie Macias tells Western Farm Press in an email. "The last 100 percent allocation was in 2006. Prior to 2006, it had been 30 years since there was a 100 percent allocation."

Abundant storms

Winter storms that swept through Caifornia enabled statewide snow-water equivalents to exceed their averages for April 1, which is considered the peak date in terms of snowpack levels, by mid-February. The statewide Sierra snowpack is 156 percent of average for March 19.

As of March 7, the DWR's Northern Sierra 8-station index recorded above average precipitation for water year 2019. While the state has not reached record precipitation like that seen in 2017, February was the third wettest recorded in the Northern Sierra index since 1921 and the sixth wettest in the San Joaquin index since 1913, according to the agency. 

The storms have rendered almost all of California free from drought, according to the U.S. Drought Monitor. Only San Diego County, portions of Orange, Riverside and Imperial counties and northern slivers of Siskiyou and Modoc counties were still abnormally dry as of March 12.

Most of the state’s major reservoirs are at or above their historical averages for this time of year. Lake Oroville, the SWP’s largest reservoir, is currently at 76 percent of capacity and 103 percent of average for mid-March, reports the DWR's California Data Exchange Center.

Shasta Lake, the Central Valley Project’s centerpiece reservoir, is at 83 percent of capacity and 106 percent of average. San Luis Reservoir, the largest off-stream reservoir in the United States where water is stored for the SWP and CVP, is at 99 percent of capacity and 112 percent of average. In Southern California, SWP’s Castaic Lake is at 81 percent of capacity and 92 percent of average.

Many factors have limited the CVP's ability to provide higher or full south-of-Delta deliveries even in wet years, asserts Christie Kalkowski, a spokeswoman for Reclamation's Mid-Pacific Region. They include regulatory constraints and limited capacity in reservoirs and canals, she says in an email.

Carryover supplies

However, in addition to this year's allocation, some CVP water remains in the San Luis Reservoir as a carryover supply from last year, she says. A new contract year began on March 1, she adds.

"This water is not part of this year’s allocation, but is CVP water that is available for those water contractors’ use this spring," Kalkowski says. "We're developing and updating estimates about how much of that allocation is available as we process the carryover requests we’ve received, as well as ongoing spring use and other factors, so we don’t have an exact number at this moment.

"We can note that for 2019, water contractors were allowed to carry over up to 10 percent of the CVP water allocated to them last year into this contract year, although the final number that was requested to be rescheduled is likely to have been less than that," she says.

The updates come as another series of storms is spritzing California this week, with scattered showers expected to linger into early Thursday while up to 3 inches of new snow accumulates above 5,000 feet, according to the National Weather Service in Sacramento. Another system Friday and Saturday is expected to add up to an inch of valley rain and 4 to 10 inches of snow above 4,500 feet, the NWS forecasts.

Dry weather is anticipated Sunday, but the wet pattern is set to resume next week, according to the weather service. The federal Climate Prediction Center foresees above-average chances of precipitation throughout California over the next month -- particularly in the central Sierra and eastern San Joaquin Valley.

The SWP serves more than 27 million Californians and 750,000 acres of farmland. The 2019 allocation of 70 percent amounts to 2,942,158 acre-feet of water, according to the DWR. The CVP has long-term agreements to supply water to more than 250 contractors in 29 of California’s 58 counties, according to its website. Deliveries by the CVP include providing an annual average of 5 million acre-feet of water for farms

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