The South Fork Merced River is the largest

tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drai ...

of the

Merced River The Merced River (), in the central part of the U.S. state of California, is a -long tributary of the San Joaquin River flowing from the Sierra Nevada into the San Joaquin Valley. It is most well known for its swift and steep course through th ...

. Most of the river flows within

Yosemite National Park Yosemite National Park ( ) is an American national park in California, surrounded on the southeast by Sierra National Forest and on the northwest by Stanislaus National Forest. The park is managed by the National Park Service and covers an ...

in the Sierra Nevada of

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

. The river is long, and its

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

covers about , of which are in the national park. The average flow at the mouth is . Originating at about on the south flank of Triple Divide Peak, the South Fork Merced River drains the southwestern slopes of Triple Divide Peak and the west facing slopes of Gale Peak and Sing Peak, then runs southwest through a pine forest flanked by

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies under ...

cliffs until the valley walls close in to become a deep canyon as the river turns west. This canyon comes to an end at a large bowl-shaped valley where the river passes the north side of Wawona and receives Chilnualna Creek from the right. After passing under Wawona Road (the south entrance road to the national park) the river drops into another broader, deeper gorge running north, receiving Alder, Rail, Big, and Bishop Creeks, all from the right. Soon the river turns west, crossing the boundary of Yosemite National Park and the

Sierra National Forest Sierra National Forest is a U.S. national forest located on the western slope of central Sierra Nevada in Central California and bounded on the northwest by Yosemite National Park and the south by Kings Canyon National Park. The forest is kno ...

and entering the

foothills Foothills or piedmont are geographically defined as gradual increases in elevation at the base of a mountain range, higher hill range or an upland area. They are a transition zone between plains and low relief hills and the adjacent topogr ...

of the Sierra Nevada, and merges with the Merced River some downstream of the end of

Yosemite Valley Yosemite Valley ( ; ''Yosemite'', Miwok for "killer") is a glacial valley in Yosemite National Park in the western Sierra Nevada mountains of Central California. The valley is about long and deep, surrounded by high granite summits such as Hal ...

. The river was mislabelled "Illilouette Creek" on 1871 California Geological Survey reports. Illilouette Creek is actually another tributary of the Merced River further to the east.

References

{{Yosemite National Park * Rivers of Mariposa County, California Rivers of the Sierra Nevada (United States) Rivers of Yosemite National Park Sierra National Forest Rivers of Northern California Rivers of the Sierra Nevada in California Wild and Scenic Rivers of the United States