Obviously, not all the water that flows down from the Sierra Nevada makes it into the Sacramento-San Joaquin Delta and San Francisco Bay.
A lot of it is used to irrigate Central Valley farmland.
However, irrigation districts are required to allow a certain amount of that water to make the entire journey -- a policy aimed at maintaining habitat for salmon and other wildlife.
Regional agricultural water providers recently blasted an ambitious new proposal by the State Water Resources Control Board that would update those regulations for the first time in more than six years.
The San Joaquin Tributary Association -- representing Merced, Modesto, Turlock, Oakdale and South San Joaquin irrigation districts -- said a recent state water board study on how hydroelectric power would be affected by proposed regulations ignored key information.
"We don't understand it. They're doing this analysis. Nobody's even contacted us," said Tim O'Laughlin, legal counsel for the association.
Mike Jensen, spokesman for the Merced Irrigation District, agreed: "We are concerned about flow requirements and how they may affect our ability to provide irrigation water to our growers and produce electricity. Given our concerns, as the process develops, MID will provide more details on the issues, concerns and potential risks to Merced County."
The process to determine the new regulations has just begun, said state water board spokesman George Kostyrko. "These (documents) were just released for an extended public comment period that will span over three months in order to give all parties an opportunity to review, comment and provide additional information to improve the analysis."
The new version of the Bay-Delta Plan -- which has been updated four times since its adoption in 1978 -- isn't due to be completed for another 10 months.
The current draft proposal would require irrigation districts, from February to June, to allow a certain percentage of the water in the Merced, Tuolumne and Stanislaus rivers to flow back into the delta. The proposed requirements range from 20 percent to 60 percent of all the water that would naturally flow into the delta.
Average springtime flows from Merced, Tuolumne and Stanislaus rivers into the delta hover around 26 percent, 21 percent and 40 percent, respectively.
Water providers are currently bound by state requirements in April, May and October, as well as federal regulations that industry advocates say are far less onerous than the proposed state plan.
Mandating new and higher flow rates would force hydropower providers to generate energy in an offseason, O'Laughlin said. "If you took flows that otherwise would have been going to farmers in the summer and move it to the springtime, you're going to short the farmers and have less power in the summer."
Those stricter proposed requirements would have dramatic effects on agriculture, he added. "At 60 percent, all the reservoirs would crash to zero periodically, once every eight to 10 years. At 40 percent, you'd release 200,000 to 300,000 acre-feet of additional water over what we're releasing now. You'd lose it. That's a lot of water." An acre-foot of water is equal to about 326,000 gallons.
The board is trying to balance the needs of industry and environment, said Kostyrko. "The board is looking at a range of alternative flow regimes and evaluating ways to minimize their effect on the agricultural industry," he said.
"Scientific reports have concluded that more flow of a natural pattern is needed from February through June for salmon- and steelhead-bearing tributaries in the San Joaquin River watershed. Determining the flows needed to protect fish and wildlife is a high priority for the water boards," Kostyrko added.
The state water board has yet to determine flow requirements for September November, December and January. Monitoring and studies have been proposed to determine what, if any, restriction on water use should be put in place for this time period.
A review of requirements for October is expected.
The state water board is scheduled to release additional environmental documents for public review on March 31. Written comments are due April 25. The state water board is expected to make a decision on flow requirements by November 2012.
Reporter Joshua Emerson Smith can be reached at
(209) 385-2486 or