Tuolumne River

Since 1981, TID has been the leading partner in conducting extensive investigations in and along the Tuolumne River to better understand Chinook salmon ecology and the factors affecting salmon production.

TID has employed one full-time biologist and hires biologist consultants that work to closely monitor the river's fishery and riparian habitat. TID uses the critical data these scientists provide to ensure that flows meet the instream requirements to sustain a healthy river environment for salmon and other species below La Grange Dam.


The Tuolumne River is the largest of the three tributaries of the San Joaquin River, the headwaters of which are formed by the snowmelt from Mt. Lyell, the highest peak in Yosemite National Park, and Mt. Dana.

From its headwaters at Mount Lyell, the Tuolumne River runs as a somewhat wavy line from east to west. The river eventually reaches the Pacific Ocean via the San Joaquin Delta. The Dana Fork of the Tuolumne River flows from Mount Dana and meets the Lyell Fork descending from Mount Lyell in Tuolumne Meadows.

The Tuolumne meanders through gorges and canyons making its way through Hetch Hetchy Valley welcoming waters from other creeks and rivers as it continues its path to its final destination. Further downstream the river flows into Don Pedro Dam and Lake Don Pedro. Downstream the Tuolumne continues its journey towards the San Joaquin River where it flows through the Delta on its way to the ocean near San Francisco.