The Merced River originates in the Southeastern corner of Yosemite National Park. Its headwaters begin at 7900 feet at the Clarke Range. It flows over Nevada and Vernal Falls, and lastly, Illilouette Creek before she flows through the main Yosemite Valley. Then the Merced, picks up water from Tenaya, Yosemite, Bridalveil, and Pigeon Creeks near the end of the valley, and meeting up the water from Cascade Creek before the river flows through the Merced River Canyon and then outside the park. Its South and North Forks join it a few miles outside the park.
The Lower Merced is another river that can be drifted, water flow permitting, or walk & waded January through May.