Bulldozers rip up Tuolumne River banks east of Modesto. The goal is better fish habitat

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In a few weeks, Chinook salmon will once again swim up the Tuolumne River looking for places to spawn.

They will encounter a dam that has blocked migration past La Grange since 1893. They will find also that mining many decades ago ruined some of the gravel beds where salmon lay their eggs. And the water can be too low during droughts such as 2020 to 2022.

The salmon are getting help from a pair of projects at La Grange that launched over the summer. One is by the Tuolumne River Trust , an environmental group. The other is just upstream and sponsored by the river's main diverters, the Modesto and Turlock irrigation districts and San Francisco.

Both projects put bulldozers and other heavy equipment to work in reshaping the Tuolumne channel back toward its natural condition.

"There's a lot of short-term disturbance for the long-term benefit," said Julia Stephens, restoration program director for the Trust. She led a Sept. 12 tour of the project site for The Modesto Bee.

State grants and ratepayer money

The Trust got a $3.7 million grant from the California Department of Water Resources for its project, which also involves the Tuolumne River Conservancy . It will completed this fall on about 10 acres in the main river channel and floodplain just downstream of the Old La Grange Road Bridge.

The other project has $2.3 million in funding from city and district ratepayers and $5.5 million from the California Department of Fish and Wildlife. It totals 10 acres and will be finished in 2025.

The Bee's visit happened to be one day before the diverters hosted other media at their restoration site. It is the first of about $80 million in projects they plan over the next decade, guided by the nonprofit River Partners.

"We're excited," said Michael Cooke, director of water resources and regulatory affairs for TID, in a San Francisco Chronicle story. "This definitely gives the fish a much better opportunity than they had before."

The Trust has long urged that the districts and San Francisco leave more water in the Tuolumne. They have offered to boost reservoir releases somewhat while also enhancing habitat with projects like the current ones.

"Obviously, we think habitat restoration is important," Trust Policy Director Peter Drekmeier told the Chronicle. "The problem is that ... gravel (for spawning) is not the limiting factor. There are other critical factors."

That debate goes on. For now, the two sides are coordinating their habitat work at La Grange. It required detailed planning and permitting, with safeguards against dust, water pollution and other impacts. Both projects will be monitored in future years to see how the fish do with the fresh gravel beds and floodplain.

The two projects are in a portion of La Grange Regional Park. The public can visit but should watch out for the earth-moving. It will be done by Oct. 15 to avoid harm to the arriving salmon.

lumne begins amid Yosemite glaciers

The Tuolumne arises amid 13,000-foot glaciers and runs freely across most of Yosemite National Park. The first diversion is at Hetch Hetchy Reservoir , owned by San Francisco. The city has rights to about an eighth of the river and supplies all or part of the water to about 2.7 million people in four Bay Area counties.

The Tuolumne turns somewhat wild again in the renowned whitewater rafting stretch north of Groveland. The paddlers end their journey in the wide, still waters of Don Pedro Reservoir. It is shared by MID and TID, which have rights to about half of the river volume. The districts irrigate about 210,000 farmland acres. Water also goes to treatment plants that reduce reliance on wells for residents of Modesto, Turlock and Ceres.

Don Pedro Dam was completed in 1971 about two miles upstream of La Grange Dam. The latter still stands as a barrier to salmon migration after 131 years.

Below the dam, the Tuolumne is reduced further by smaller water rights holders before it flows into the San Joaquin River. The Tuolumne is about 20% of its historical level in an average year. Drought can knock it to 10%. The Trust and its allies would like to see at least 40% in the future, an issue still before state and federal agencies.

A few years at sea before returning

The Tuolumne is near the southern end of the Chinook's range along the Pacific coast of North America and Russia. The fish spawn in hundreds of rivers and then spend two to five years at sea.

The Tuolumne's baby fish must contend each spring with massive pumps in the Sacramento-San Joaquin Delta that send much of its water south. Striped and black bass, introduced in the late 1800s for sport fishing, prey on the native salmon. The delta can be too warm and polluted in below-average years for runoff. The off-shore fishing season can be canceled if conditions warrant.

Adult salmon run the gauntlet in reverse when they come back to spawn on the Tuolumne. This happens mainly from October to December upstream of the Hughson area. The females look for gravel bars where they can deposit their eggs, fertilized by the males. Ideally, the river has numerous "riffles," undulations caused by small rocks that provide oxygen for the fish. The adults then die and decompose into food for microbes and other creatures.

Before the dams were built, the spawning beds were replenished often by heavy flows from upstream. The salmon also have suffered from mining with dredges, far more destructive than the gold panners of the 1850s. These machines moved large rocks aside to get at the gold-bearing sediment below. They left piles of waste known as tailings in place of what should be a relatively flat floodplain. The largest dredge ran from 1938 to 1951.

"A lot of what was lost with this upending of the layers of sediment was wetland habitat," Stephens said.

The dredging left holes in the riverbed that are deeper than desired and attract the predatory bass. They are being filled in, and the river will get riffles in several spots.

"Naturally, the river would have more complexity to it," Stephens said. "It would have more meanders."

Precise work by backhoe operator

The Trust hired a Sacramento-based company called Triangle Properties for the earth-moving. It is part of Teichert Inc. based in Sacramento, which mainly builds roads and other public works.

The crews will haul about 31,000 cubic yards of rock and dirt overall, said Triangle supervisor Mike Peterson. He spoke next to a spot where backhoe operator Ernesto Gutierrez was creating the 0.1% slope needed for this type of floodplain. "He's an artist," Peterson said.

Other employees were driving excavators, bulldozers, front loaders, dump trucks and water trucks to keep down the dust. Earlier this summer, the site had a gravel washing machine, turning out the clean rock favored by salmon.

The site will get about 27,000 native plants and grass seed to prevent erosion. The plants will include fast-growing trees such as willow, cottonwood and ash. They will shade young salmon as they prepare for the ocean journey. The branches also harbor mayflies and other bugs that fall into the water and become fish food.

This year is the first phase of a $26 million effort that is mostly unfunded, Stephens said. Its formal name is the Basso/La Grange Restoration Project. Basso Bridge is part of a footpath about two miles downstream.

Stephens suggests another bridge, on Old La Grange Road, where the public might spot the returning salmon this fall. "You can see them shaking their tails at times to lay their eggs."

The project also could aid steelhead trout, which spend time in the ocean. Resident creatures could benefit as well, such as the Western pond turtle and foothill yellow-bellied frog.

Other restorations down to Dos Rios

La Grange has small pieces of a restoration effort that also is happening around Modesto and farther downstream. The largest by far is Dos Rios Ranch, where the Tuolumne meets the San Joaquin. It has about 1,600 acres of floodplain forest and in June became a state park .

San Francisco helped fund Dos Rios, which also had support from River Partners and the Tuolumne River Trust. The city's new La Grange project is the start of an $80 million commitment with MID and TID, the Chronicle reported.

"Frankly, what we're seeing is a new era of working together on habitat restoration," said Steve Ritchie, an assistant general manager at the San Francisco Public Utilities Commission.