Meeting will explore fish passage on Tuolumne

The public can weigh in again Thursday on the idea of conveying salmon and steelhead trout past Don Pedro and La Grange reservoirs on the Tuolumne River.

The Modesto and Turlock irrigation districts could have to undertake the project – at a cost of perhaps $70 million to $150 million – as a condition of a federal hydroelectric license. The system would use ladders, canals, trucks or other means to get the fish around the nearly 30 river miles occupied by the reservoirs when full.

The districts have been working since 2011 on the relicensing of Don Pedro, which was completed in 1971 and has by far the larger capacity of the two reservoirs. The fish-passage issue arose when the Federal Energy Regulatory Commission ruled in 2012 that La Grange also needed a license. It was completed in 1883, decades before licenses were required.

Thursday’s meeting at the MID office will be the second in a series of three on the fish-passage issue. It will deal with current conditions on the Tuolumne and the possibility of getting fish upstream by various means.

Fishery agencies and environmental groups have said the passage could be needed to make up for the loss of spawning and other habitat to the dams. Salmon and steelhead returning from the Pacific Ocean to spawn now can get about 50 miles up the Tuolumne. A passage could introduce them to about 25 more miles of the main river, along with several tributaries.

Critics of the idea question whether the fish swam that far in pre-dam days, and they also note the cost to the districts’ water and power customers. At a TID board meeting last month, directors also noted the low number of salmon that might be helped, perhaps 500 to 1,000 a year.

The cost, design and other details of the fish passage are being refined in a study expected to take two years.

This story was originally published September 14, 2015 at 3:43 PM with the headline "Meeting will explore fish passage on Tuolumne."