Tuolumne River

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Tuolumne River
The Tuolumne River flows through Tuolumne Meadows in Yosemite National Park
Country United States
State California
Districts Stanislaus County, Tuolumne County, Mariposa County
 - left Falls Creek (California), Middle Fork Tuolumne River, South Fork Tuolumne River
 - right Clavey River
City Modesto, California
Primary source Lyell Fork Tuolumne River [1]
Secondary source Dana Fork Tuolumne River
Source confluence Tuolumne Meadows
 - location Yosemite National Park
 - elevation 8,583 ft (2,616 m) [2]
 - coordinates 37°52′32″N 119°21′11″W / 37.87556°N 119.35306°W / 37.87556; -119.35306
Mouth San Joaquin River
 - location Modesto
 - elevation 26 ft (8 m)
Length 148.7 mi (239 km)
Basin 1,960 sq mi (5,076 km2)
Discharge for above La Grange Dam
 - average 2,340 cu ft/s (66 m3/s)
 - max 130,000 cu ft/s (3,681 m3/s)
 - min 61 cu ft/s (2 m3/s)
Map of the Tuolumne River watershed

The Tuolumne River (/tˈɒləm/; Yokutsan: Tawalimnu)[3] is a California river that flows for 149 miles (240 km) from the central Sierra Nevada to the San Joaquin River in the Central Valley. The river is formed by the confluence of the Lyell and Dana Forks in Yosemite National Park; from there it flows generally westward through the foothills of the Sierra Nevada where it is dammed by the New Don Pedro Dam, through farmland in the Central Valley, to its mouth near Modesto. The unique granitic features of the Tuolumne River's upper watershed were shaped by glaciation in the previous Ice Age, which produced such formations as Hetch Hetchy Valley and the Grand Canyon of the Tuolumne.

The river's water has been a source of contention for many years. About 15% of the total flow is diverted to San Francisco from Hetch Hetchy Reservoir, which floods an eponymous valley in the Sierra Nevada once compared to Yosemite Valley for its natural beauty. Further downstream, about one-half of the river flow is diverted at La Grange Dam to irrigate farmland in the Central Valley.

The Tuolumne River system is a popular hiking and backpacking destination in Yosemite National Park; between Hetch Hetchy Reservoir and Lake Don Pedro, the river is well known for its whitewater.


The Dana Fork of the Tuolumne River

The Tuolumne headwaters are along ~35 mi (56 km) of the Sierra Crest from the triple watershed point with the Stanislaus River southward over Mount Dana and the triple point for the Dana & Lyell Forks (37°49′05″N 119°13′02″W / 37.818056°N 119.217238°W / 37.818056; -119.217238) to the Upper San Joaquin triple point near Mount Lyell. The Tuolumne source is the confluence of the Dana Fork (from Mount Dana) and the Lyell Fork (from Mount Lyell) in the Tuolumne Meadows. After the subsequent confluence with Cold Canyon & Conness Creek, the Tuolumne flows through Glen Aulin (Gaelic: beautiful valley) where the valley walls pull away from each other and become steeper and the meandering riverbed is quite level and forms deep pools. Just northwest of Glen Aulin, the River presents spectacular waterfalls, including LeConte Falls and Waterwheel Falls, both known for the "waterwheel" phenomenon whereby descending water hits rocks below and wheels back upward.

At this point, the Tuolumne enters the Grand Canyon of the Tuolumne. This canyon is a deep, roughly 'V'-shaped gorge. The walls are not as steep and bare as those of Yosemite Valley. The flora of the valley bottom is a haphazard melange of chaparral, manzanita scrub and oak woodland characteristic of the foothills and lowlands with a coniferous forest reminiscent of (but different from) that found above the canyon rim. This vegetation clings and clambers up every ledge of the valley walls to the top, giving it a lusher appearance than Yosemite Valley, though this area in fact experiences a drier climate. Class IV whitewater is in an 18-mile section from Meral's Pool to Ward's Ferry Bridge.[4]

Below the Grand Canyon lies Hetch Hetchy Valley. The river bottom flattens again, and the canyon walls pull away and become steeper, in a fashion similar to that of Yosemite Valley; this valley was once perhaps the most spectacular part of the Tuolumne's course. However, at the bottom of Hetch Hetchy Valley stands O'Shaughnessy Dam, which floods the entire valley under the Hetch Hetchy Reservoir. Before the river leaves the dam, Falls Creek, Tiltill Creek and Rancheria Creek enter from the right. Here, some water is diverted into the Hetch Hetchy Aqueduct, which serves municipal water to cities in the San Francisco Bay Area.

Below the dam, the river flows through the Stanislaus National Forest, within which it is joined by Cherry Creek, the South Fork of the Tuolumne River, and the Middle Fork of the Tuolumne River. Far below the town of Groveland, the river is designated Wild and Scenic. This portion is popular for rafting and kayaking and is joined by the Clavey River.

Still farther downstream lie New Don Pedro Dam and Lake Don Pedro, which store water for irrigation and produce hydroelectricity. Directly below New Don Pedro Dam is La Grange Dam, which diverts water to serve farms in the Modesto Irrigation District and Turlock Irrigation District. From La Grange Dam the Tuolumne flows about 50 mi (80 km) west, past Waterford, Empire, Ceres and Modesto. At Modesto, the Tuolumne is joined by Dry Creek from the right. The Tuolumne empties into the San Joaquin River at the San Joaquin River National Wildlife Refuge two miles (3.2 km) north of Grayson.

Points of interest[edit]

Hetch Hetchy Valley — by Albert Bierstadt; oil painting; c. 1870s. (before submersion)

Towns along the Tuolumne River:

Cities along the Tuolumne River:

The Modesto Airport lies next to the Tuolumne River. Between the airport and the river lies Veterans' Park.


The Native Americans along the Tuolumne were the Paiutes and Miwoks. The Miwoks lived along the western part of the Tuolumne from Big Oak Flat down to the valley floor, while the Paiutes camped primarily east of that point towards the high Sierra Nevada. The Washoe Indians also visited the area. The Tuolumne River Trust was founded in 1981.[5]

See also[edit]


  1. ^ "Tuolumne Meadows". Yosemite Region. SierraFlyFisher.com. Retrieved 2010-08-24. The Dana and Lyell Forks converge to form the main Tuolumne river 
  2. ^ "USGS Elevation Web Service Query". United States Geological Survey. Retrieved 2010-02-19. 
  3. ^ The Indian tribes of North America. Retrieved 3 April 2011. 
  4. ^ "Tuolumne River Rafting & Kayaking". Guide to Rafting and Kayaking. Californiawhitewater.com. Retrieved 2010-08-24. 
  5. ^ Tuolumne.org "Vision and Goals" Check |url= scheme (help). Tuolumne River Trust. Retrieved 2010-08-24.