MODESTO — A state board proposes to help fish by reducing average annual diversions on the Tuolumne River by 15 percent and on the Merced River by 13 percent.

The idea drew protest last week from water suppliers, including the Merced, Modesto and Turlock irrigation districts, which argue that the reductions would be especially tough in dry years.

A fishing industry leader, on the other hand, said even more water is needed in the rivers.

The proposal came from the State Water Resources Control Board, which aims to improve conditions for salmon and other life in the lower rivers as well as the Sacramento-San Joaquin Delta.

Most of the increased flows would happen from February through June each year, when young salmon are heading out to the Pacific Ocean, but the districts are trying to store water for summer.

"Restoring our fisheries is not a problem that can be solved by simply throwing more water down the river," said Allen Short, executive director of the San Joaquin Tributaries Authority, in a news release.

Short, who retired as the Modesto Irrigation Districts's general manager last month, now heads a group made up of several water suppliers on the Tuolumne, Merced and Stanislaus rivers.

They include the Merced, Modesto, Turlock, Oakdale and South San Joaquin irrigation districts, as well as the San Francisco-owned system that supplies many Bay Area residents.

"(Merced Irrigation District) is very concerned with the approach the (board) is taking," said John Sweigard, general manager for Merced Irrigation District. "(The board) has disregarded the best available science about stressors affecting the fishery. An independent science panel -- which was invited by the water board -- presented sound evidence to the board showing that there are many stressors affecting the fishery: predation, loss of habitat in the delta, poor ocean conditions and ocean harvest policy."

Sweigard added that Merced Irrigation District has been proactively providing increased flows down the Merced River to benefit salmonids during their fresh water life cycle for more than 15 years. "As California's water resources become ever more stressed due to population increase, climate change and other factors, it becomes more imperative to apply smart, targeted management practices to our resources. Blindly releasing more water to the ocean is not an answer," he said.

The proposal would reduce average annual flows in the Stanislaus by 3 percent because it already contributes a greater share to fisheries than the other rivers. This did not ease the concerns of the critics, who said the overall plan relies too much on increasing flows.

Under the proposal, which the state board could approve in August, the February-June flows on all three rivers would increase to 35 percent of the natural conditions before they were diverted.

The rivers need to run at twice that volume if the depleted fisheries are to recover, said Zeke Grader, executive director of the Pacific Coast Federation of Fisherman's Associations.

Commercial fishermen in the San Francisco-based group endured shutdowns of salmon fishing in 2008 and 2009.

"I don't think anyone wants to do away with agriculture, but at the same time, we need to take a look at what kind of crops we are growing," Grader said.

The state board said the increased flows would cut farm income in the region by just 1 percent. Reduced water supplies would likely mean that farmers turn from lower-value crops such as corn to higher-value crops such as almonds, the board said.

The irrigation district group said fish would benefit more from nonflow measures such as restoring streambeds, reducing predation by non-native striped bass, changing ocean fishing rules and improving hatchery practices.

"If you're going to ask people to make this serious sacrifice," Short said, "you'd better be darn sure you know what the benefits are, and the fact is, they have not even estimated what, if anything, will be achieved by increasing flows."

The proposal would shift much of the districts' hydroelectric generation to earlier in the year, when it is of less value, but the loss would not be substantial, the board said.

The proposal comes as the Modesto Irrigation District and the TID are seeking a new federal license for the Don Pedro hydropower plant. This process could result in increased flows downstream, but managers have said they should not be on top of what the state board requires.

WHAT'S NEXT

MARCH 5: Deadline for written comments on proposed flows in lower Stanislaus, Tuolumne and Merced rivers

MARCH 20: Workshop on proposed flows at State Water Resources Control Board, Sacramento; time to be announced

MAY 3: Draft final proposal to be released for comment

AUG. 6: Possible final vote

ON THE NET: www.waterboards.ca.gov/ waterrights/water_ issues/programs/bay_delta