Central Valley Project slashes projected water deliveries
February 26, 2013
• Dry January and February prompt cuts
• “We continue to hope for additional precipitation during the remainder of the rainy season”
Some farmers on the west side of the Central Valley might be growing more dust than crops this year as the federal Central Valley Project slashes water deliveries to agricultural customers south of the Sacramento-San Joaquin Delta.
Based on current water storage and estimates for new rain or snow in March, the Bureau of Reclamation says agricultural water service contractors South-of-Delta are being allocated just 25 percent of their contract supply of 1.965 million acre-feet of water.
Municipal and industrial water service contractors South-of-Delta are allocated 75 percent of their historic use.
Famers can in some cases pump ground water to irrigate their crops, but this is generally more expensive than water from the CVP.
San Joaquin River Exchange and Settlement contractors, whose CVP water supply allocation is subject to pre-established Shasta Reservoir inflow criteria, are allocated 100 percent of their contract supply of 875,000 acre-feet.
Lack of any significant storms in January and February has helped diminish the Sierra Nevada snowpack with the snow water content statewide at 70 percent of average for this time of year.
Additionally, the California Department of Water Resource’s February runoff forecast indicates a dry water year type for the Sacramento Valley and a critical water year type for the San Joaquin Valley, the Department of the Interior says.
The 2013 water year is unfolding in a unique way. The federal Bureau of Reclamation began the current water year (on Oct. 1, 2012) with 6.9 million acre-feet of carryover storage in six key Central Valley Project reservoirs, which is 98 percent of the 15-year average for Oct. 1. Storms in late November and December resulted in above-average snowpack conditions in Northern California and contributed to above-average storage in Shasta and Folsom Reservoirs.
However, the San Joaquin River watershed did not fare as well. This mixed start to the water year was then followed by one of the driest combined Januarys and Februarys on record, leading to what has become “a challenging water year,” as the Bureau puts it.
In addition, water supplies from the state and federal pumps in the south Delta have been reduced significantly to protect delta smelt, a threatened species under the Endangered Species Act.
Storms in December 2012 flushed large amounts of sediment into the Delta, which may have set up a situation for elevated delta smelt migration into the central and south Delta well into February, the Bureau says. Reclamation began to cut back on pumping operations in late December to protect the smelt, and pumping reductions have been required throughout January and February.
“While we continue to hope for additional precipitation during the remainder of the rainy season, we are also continuing to work with our federal, state and local partners to improve this year’s supply and to find a comprehensive, long-term solution that will achieve the dual goals of a reliable water supply for California and a healthy Bay Delta ecosystem that supports the state’s economy,” says Bureau of Reclamation Mid-Pacific Regional Director David Murillo.
Reclamation determines the allocation of CVP water for agricultural, environmental, and municipal and industrial purposes based upon many factors. This initial allocation, based on a conservative runoff forecast, is driven by very dry hydrologic conditions in January and February, water quality requirements, flow objectives, relative priority of water rights, and endangered species protection measures, including operational adjustments in accordance with biological opinions to protect threatened and endangered fish species.