Debate churns again over salmon passage around Don Pedro Reservoir

Experts offered some detail Thursday on the idea of moving salmon above Don Pedro Reservoir – and they heard from a critic who thinks it’s way too costly.

The Modesto and Turlock irrigation districts held a fifth public meeting on a proposed system for conveying the fish around Don Pedro, which covers about 30 miles of the Tuolumne River when full.

The fish passage, a possible condition for a federal hydropower license, could cost several hundred million dollars. It would involve mechanized ladders, trucking, canals or other methods for getting the oceangoing fish to and from possible spawning areas.

Don Swatman of Modesto, a retired dentist, said the project would save just a few of the native river fish and that the reservoir is fine as is for recreation.

“There have been as many, on a weekend day, as 4,000 families with boats and kids enjoying Don Pedro,” he said.

The districts are in the midst of relicensing Don Pedro, but the fish passage issue is actually part of the license for the much smaller La Grange Reservoir, 2 miles downstream of the main storage.

Thursday’s meeting dealt mostly with the studies this year and next on conditions in the part of the river that would get the salmon. It stretches about 25 miles from the upper extent of Don Pedro to the area where San Francisco diverts its share of the Tuolumne.

Experts are trying to determine whether salmon swam that high before the 1893 completion of La Grange Dam. They are testing whether the water is cool enough for these fish. They are looking for insects and other food for the salmon, and for the streambed gravel where they lay their eggs.

Scientists also are modeling flows that could range from 50 cubic feet per second in a dry year to 2,000 in a wet year. And they are assessing the effect of the daily fluctuation due to releases from a San Francisco power plant.

The passage also could aid steelhead trout, which also swim out to sea, if the study team finds evidence of them.

Another study involves the social and economic effects of a fish passage, including the cost to the districts’ water and power customers. This part also will deal with impacts on recreation on Don Pedro and on users of the river above and below it.

“So if there are new fish there, what does it mean – anything that might be impacted positively or negatively,” said Jenna Borovansky, senior regulatory specialist with the HDR consulting firm. It is guiding MID and TID through the process at the Federal Energy Regulatory Commission.

Peter Drekmeier, policy director for the Tuolumne River Trust, noted that salmon in the upper river could give rise to a fly-fishing venture.

This story was originally published May 19, 2016 at 7:23 PM with the headline "Debate churns again over salmon passage around Don Pedro Reservoir."