Farms, fish and water fun —and $159 million —in 50-year Don Pedro Reservoir plan

The owners of Don Pedro Reservoir made their pitch Tuesday for how it can serve both people and Tuolumne River fish over the next half-century.

The boards of the Modesto and Turlock irrigation districts each voted 5-0 at separate meetings to submit their final application for a new federal license for the project.

The proposal, six years in the making and topping 6,000 pages, mainly deals with how to boost the number of salmon on the 52 miles of river below Don Pedro. The districts offer to increase reservoir releases from current levels, but much less than sought by environmental and fishing groups.

“This plan balances the needs of the people with a healthy fishery,” TID board member Michael Frantz said.

The districts have spent about $32 million to date to study fish, riverside creatures, reservoir recreation and other topics. They project another $159 million in construction and other costs related to the improvements. Their customers would cover the tab over the term of the license, which could be as long as 50 years.

MID and TID completed Don Pedro under a license granted in 1966. It expired in 2016, but the Federal Energy Regulatory Commission has extended it so the new application could be completed. The new target is 2020, following public comment and further study by FERC.

The reservoir is the state’s sixth largest at 2.03 million acre-feet. The districts supply farmers on about 208,000 acres in Stanislaus and Merced counties, and MID provides part of Modesto’s city water. Don Pedro also draws many people for camping, boating and other recreation.

The districts propose boosting releases by about 35 percent on average over the 26 miles from La Grange to the Geer Road bridge. There, some of the water would be diverted to a treatment plant being planned to supplement city wells in Turlock and Ceres. The river below that point would run at 12 percent more than current conditions on average.

The water planned for city use is now diverted at La Grange for farming, but salmon could benefit if it flows all the way to Geer and the treatment plant.

The Tuolumne River Trust, one of the groups seeking much higher flows, had not seen details of the TID-MID plan as of Tuesday, said Executive Director Patrick Koepele by email.

“Our vision for the new license remains the same, however,” he said. “We would like to see a new license that supports a healthy river ecosystem and recreational opportunities, as well as the agricultural economy in the region. We will be reviewing the license application in the coming days to assess how well it accomplishes that.”

The districts contend that reservoir releases could be modest because salmon would benefit more from non-flow measures. They propose restoration of gravel spawning beds, control of non-native bass that prey on salmon, and removal of water hyacinth that can clog the lower river at low flows. The plan also includes a new hatchery that would help with survival of the eggs laid by salmon returning to the Tuolumne after a few years in the Pacific Ocean.

The FERC process coincides with a state proposal to sharply increase flows on the lower Tuolumne, Stanislaus and Merced rivers. The State Water Resources Control Board heard vigorous debate at several hearings and could issue a refined plan later this year.

FERC has authority because Don Pedro has a hydroelectric plant. The application also includes the much-smaller La Grange Reservoir, about two miles downstream.

The districts’ plans do not include a system, suggested by some salmon advocates, that would convey the fish to the Tuolumne upstream of Don Pedro. This would add to spawning and rearing habitat but could cost several hundred million dollars.

This story was originally published October 10, 2017 at 3:02 PM with the headline "Farms, fish and water fun —and $159 million —in 50-year Don Pedro Reservoir plan."