Tuolumne River Trust looks out for salmon amid drought
Seven canoes carried 11 people to see how Tuolumne River salmon are faring after three years of drought.
The Tuolumne River Trust organized the Nov. 12 trip to press its point that too much water goes to farms and cities.
The group paddled the two miles between the La
Grange and Basso bridges, near the upstream end of the 25-mile spawning stretch. Chinook salmon come here each autumn after a few years in the Pacific Ocean to reproduce and die, one more turn of an ancient life cycle.
The returning fish contend every fall with the massive pumps that send water far south from the Sacramento-san Joaquin Delta. Dry years like 2022 reduce the volume of the Tuolumne and can raise its temperature. Many of the gravel spawning beds were disrupted long ago by mining and dams.
“Historically, there were well over 100,000 salmon spawning in the Tuolumne,” said Peter Drekmeier, policy director for the Trust, before the canoes set out. “... Last year, there were under 600. It looks like this year will be slightly better.”
The Modesto and Turlock irrigation districts, the main users of the river, defend their handling of the fishery during the drought. They also say it will improve over the long term if the state approves a tentative compromise on how much reservoir water to release into the lower Tuolumne. The deal also would involve San Francisco, which diverts part of the river upstream.
These water suppliers say the agreement would be especially helpful by boosting flows from January to June, when newly hatched salmon head out to sea.
“Site-specific science on the Tuolumne shows that combination of flow and nonflow measures will lead to an improved fishery on the Tuolumne River,” said a Nov. 16 email from Michael Cooke, director of water resource and regulatory affairs at TID.
Chinook range to Bering Sea
The San Joaquin Valley is the southernmost reach of the chinook range, an arc off the coast from California to the Bering Sea. They are commercially fished in areas with adequate numbers to support a season, which is hit-and-miss in this drought-prone state.
Tuolumne salmon surpassed 100,000 in the millennia before dams blocked part of the spawning area and shifted water to human uses. They still can abound at times, such as the 40,322 estimated in 1985 by the California Department of Fish and Wildlife. That resulted mainly from the very wet 1982 and 1983. Salmon also can benefit from good ocean conditions during the two to five years they are out there.
The Stanislaus River had about 6,000 spawning salmon last year, 10 times the count on the neighboring Tuolumne. That stream has stricter rules for reservoir releases, along with habitat projects by the Oakdale and South San Joaquin irrigation districts and other partners.
The Tuolumne River Trust formed in 1981 to advocate for a waterway that begins amid 13,000foot glaciers in Yosemite National Park. It also works on watershed health, including wildfire fuel reduction, and educating Stanislaus County residents about the river that runs by them.
MID and TID divert about half of the runoff at Don Pedro Reservoir, just east of the salmon spawning area. San Francisco gets about an eighth. Riverside rights holders take smaller amounts, leaving about 20% of the Tuolumne reaching the delta in an average year.
Don Pedro brought new rules
The salmon rules were set in the federal license that led to the 1971 completion of Don Pedro. It was amended by a 1995 agreement that modestly increased flows.
In 2018, the State Water Resources Control Board approved a plan that would roughly double releases to the lower river. The vote drew applause from environmental and fishing groups, and protests and a lawsuit from the diverters. It has yet to be carried out.
The districts and San Francisco have offered to boost the lower-river volume somewhat while also upgrading fish habitat with nonflow measures. They include restoring gravel in part of the spawning area and creating a new floodplain forest, which offers shelter and food to the young salmon.
Critics question whether these improvements would work under the water releases proposed by the diverters. “That gravel is going to be just gravel unless water flows over it,” local environmental activist Doug Maner said over Zoom at a Nov. 15 update for the MID board.
Cooke, the TID official, addressed this point: “The terms of the voluntary agreement require that the habitat developed by the districts and San Francisco will be inundated with the increased flows ....”
The diverters cite another threat to young salmon: being eaten by bass species introduced to California more than a century ago. They say controlling them is as important as flow increases to the health of the native fish.
The diverters propose a barrier that would allow steelhead trout and salmon to migrate while blocking the larger bass. They also suggest raising catch limits for the invaders and fishing derbies that target them. These ideas have drawn protest from bass fishing guides in the delta, who want to sustain the population even though it is not native.
The Tuolumne River Trust agrees that predation is a problem, but mainly because diversions have left the slower, warmer water favored by bass.
Water treatment plant has role
One key improvement for fish will happen next year with the completion of a water treatment plant for Turlock and Ceres residents. The plant will use some of TID’S farm water, but it will be diverted about 25 miles downstream of current canal intake near La Grange. The water will bolster habitat down to about Geer Road, then go through grates in the river bottom to the plant.
TID agreed to supply the project because it will reduce the two cities’ reliance on wells, aiding an aquifer also tapped by farmers. The Modesto area has done the same with a river treatment plant completed by MID in 1994.
The two districts irrigate a total of about 210,000 farmland acres and are key drivers of the food and beverage processing in the region. San Francisco provides varying portions of the water for 20-plus cities in the Bay Area.
The Trust supports the increased flow resulting from the new treatment plant, Drekmeier said at an Oct. 25 meeting of the Stanislaus County Water Advisory Committee. And he cited past efforts at cooperation, notably 1,600 acres of floodplain restoration at Dos Rios Ranch, where the Tuolumne meets the San Joaquin River.
The Trust urges the districts and San Francisco to use water more efficiently. The suppliers respond that they try to do so but still need to keep the lower-river releases at a moderate level.
‘A salmon-based ecosystem’
The Tuolumne was running at about 150 cubic feet per second the day of the canoe trip. That’s the minimum required during spawning and amounts to 298 acre-feet per day. Cooke said the districts voluntarily added a total of about 12,000 acre-feet between Oct. 17 and 31 to fine-tune the effort.
“These pulses were coordinated with fishery agencies in order to shape the pulses for the greatest environmental benefit,” he said.
The districts have to balance the fish with the need to hold water in Don Pedro in case 2023 is a fourth straight dry year. Farmers had no cap in 2020 but were at about 80% of normal last year and 60% this year.
Drekmeier reported back on the trip in a Nov. 21 email. The group saw about 30 salmon, bringing the total to just 440 as of midmonth. The spawning continues through December.
The Trust led four such trips in November, an annual fundraiser called Paddle with the Salmon. Novices got lessons in how to navigate the occasional riffle or eddy and how to spot fish headed upstream to spawn.
They also might see, and smell, those that have died and are decomposing into food for birds, microbes and other scavengers.
“It really is a salmon-based ecosystem,” Drekmeier said, “because the salmon bring all these nutrients from the ocean to the upland habitats, and they fuel the food web and help fertilize the soil.”