U.S. Bureau of Reclamation
The driest January through March on record is causing water supply challenges for much of California, particularly for the Central Valley Project (CVP) agricultural water service contractors in the western San Joaquin Valley (SJV).
The Bureau of Reclamation, working closely with the California Department of Water Resources (CDWR), has implemented several actions to improve water supply conditions south of the Sacramento-San Joaquin Delta, and is preparing to implement certain additional actions in the near future.
Five specific actions are improving CVP water supplies by more than 100,000 acre-feet to support current Westside water allocations. Several other actions to augment future water supplies, including water transfers, could total another 200,000 acre-feet.
In addition, new rescheduling guidelines implemented by Reclamation this past winter have allowed CVP contractors to carry over 225,000 acre-feet of the 2012 supplies for use in 2013.
“Reclamation is currently working every prudent avenue, with our partner agencies and customers, to deliver water to where it is needed in this critically dry year,” said USBR Mid-Pacific Regional Director David Murillo.
“For the long-term, successful completion of the BDCP, including a new diversion and conveyance facility, would have state of the art protections for the benefit of endangered fish species, would help restore some of the natural flow of water through the Delta, and would provide some certainty and stability to California’s water supply.”
The CVP provides water for agricultural, municipal and industrial, and environmental purposes through complex processes, driven by numerous factors, including hydrology, operational limitations, environmental considerations, regulations, court decisions, and climate changes.
Actions included as factors in calculating the current CVP allocation for south-of-Delta water service contractors include:
1 - Delta-Mendota Canal Intertie - Use of the Intertie between the Delta-Mendota Canal and the California Aqueduct, located in Alameda County west of Tracy. The Intertie has been used to improve water supplies by 38,000 acre-feet to date in 2013.
2 - Yuba River Accord - Through an agreement with CDWR, a portion of the water made available by the Yuba County Water Agency will add to CVP supplies this summer. After system losses, the CVP will likely receive about 24,000 acre-feet.
3 - CVP Water Use Flexibility - Under a “flexibility” agreement, San Joaquin River Exchange Contractors have used alternative sources of water supply early in the year to delay use of CVP water supplies from the Delta.
This potentially provides more Delta water supplies for delivery to CVP water service contractors on the west side of the SJV during the peak irrigation season. About 9,000 acre-feet of water demand is projected to be shifted for user later in the year.
4 - Stanislaus River Fishery Flows - Reclamation is accommodating the release of water from senior water rights holders on the Stanislaus River for fishery benefits, with secondary benefits of improving Delta exports to the CVP and State Water Project.
The water would be released from New Melones Reservoir in April and May. A portion would be diverted for CVP and SWP use. About 30,000 acre-feet will likely be available for supplemental CVP allocation.
5 - Refuge Groundwater Pumping - Groundwater wells in the Grasslands Resource Conservation District and the Grassland Water District will be available to pump additional water. Half of the water pumped will be used to meet refuge Level 2 water demands in lieu of using CVP water, with a like amount of water going back into the CVP yield for allocation to the west side of the San Joaquin Valley.
The estimated total quantity of pumped groundwater will be about 4,000 acre-feet, making 2,000 acre-feet available to improve CVP supplies.
Reclamation’s actions to augment future water supplies include:
1 – Water banking - Since 2001, Reclamation has approved 20 requests from CVP contractors to bank CVP water for use in dry years. So far this year, Reclamation has approved the return of 20,000 acre-feet of banked CVP water to south-of-Delta water users for the 2013 water year.
2 – Water transfers - Reclamation approves the transfer of CVP water and enters into Warren Act contracts for the movement and storage of non-CVP water transfers. Reclamation is evaluating the quantity and timing of water transfer opportunities through the Delta this summer. Transfers allow CVP contractors to augment their CVP allocation.
Reclamation’s actions are helping to offset the impacts of this year’s dry hydrology, exacerbated earlier this winter when pumping was restricted for a certain period of time to protect salmon and other fish species, leading to the loss of approximately 250,000 acre-feet of water for south-of-Delta CVP contractors.
More information on CVP water management is available at www.usbr.gov/mp/PA/water/index.html.
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