East of El Portal near Yosemite, the Merced River is a popular river for big brown trout and rainbow trout. The fast river start high up in Yosemite National Park, and the most popular section is below the park entrance near the small town of El Portal. In spring, this river runs really fast -- wader need to watch their step all season long on the slippery rocks.
The Merced River is easily accessed from one of the many turnoffs on SR140.
Overall, Merced River is the 5th most popular fly fishing river of all 17 fly fishing spots in California.