Irrigation district board members raised questions Tuesday about a costly proposal to help Tuolumne River fish get around Don Pedro Reservoir.
The project could cost $70 million to $150 million and benefit perhaps 500 to 1,000 salmon a year, consultant John Devine said at a meeting at the Turlock Irrigation District.
It nonetheless could be a condition of the new federal licenses being sought by TID and the Modesto Irrigation District for Don Pedro and the much-smaller La Grange Reservoir just downstream.
“If we’re going to spend $100,000 per fish, that’s ridiculous,” TID board member Rob Santos said. “It’s asinine.”
His per-fish figure is within a wide range based on the estimates discussed Tuesday. It would be $70,000 per salmon if the passage costs $70 million and aids 1,000 of them. It would be $300,000 each if the cost is $150 million and just 500 benefit. Steelhead trout also could use the passage.
Such a project could take various forms – ladders that lift fish near a dam face, canals or pipelines that get them around a reservoir, trucks that haul them to a desired spot.
The cost estimates, still rough, are more than they were at a May meeting on the topic, when they ranged as high as $110 million. The cost and other details are being refined in a study expected to take two years. Water and power customers of the districts would likely cover the costs; Devine said federal funding is unlikely.
Advocates for a Tuolumne passage say it could enhance spawning and rearing habitat on a river that is heavily used by farms and cities. Salmon and steelhead now hatch in the Tuolumne downstream of La Grange, then head to the Pacific Ocean before returning in a few years to spawn.
30 Length in miles of proposed fish passage around Don Pedro and La Grange reservoirs
500 Vertical feet between lower and upper parts of passage
“The conclusion that fish passage would benefit relatively few fish does not have a basis,” said Patrick Koepele, executive director of the Tuolumne River Trust, in an email Tuesday. “The purpose of the study is to assess the potential for fish passage. Remember, 80 percent of salmon and steelhead spawning habitat is blocked behind dams, and it is higher-quality habitat.”
The National Marine Fisheries Service has suggested that it will require a fish passage as a condition of new hydropower licenses from the Federal Energy Regulatory Commission. One would replace the 1966 license that led to the 1971 completion of Don Pedro. La Grange dates to 1893, long before licenses were required, but FERC ruled in 2012 that it needs one.
Most of the licensing debate has involved increasing flows for fish on the lower river, which would mean less water for farms and cities. The fish passage would add considerably to the costs.
TID and MID would likely have one of the largest such systems in the nation, said Devine, an engineer with HDR Inc., a global firm. Fish returning to spawn would be conveyed about 30 miles from La Grange Dam to just above the upper extent of Don Pedro, with an altitude gain of about 500 feet. Another part of the system would guide ocean-bound fish to the lower river.
TID directors said the passage would do little about a key factor in salmon decline – predation by striped bass and other nonnative fish. Devine said the system would have to use nets or other measures to keep the predators from feasting.
The study is looking at potential fish habitat on the nearly 25 miles of the Tuolumne’s main stem between Don Pedro’s upper end and the Hetch Hetchy Water and Power System, which serves much of the Bay Area. It also involves several tributaries, including the Clavey River; Cherry Creek; and the north, middle and south forks of the Tuolumne.
The study will look at tree cover, water temperature, natural river barriers and other conditions on the streams.
John Holland: 209-578-2385