 The Merced River and its tributaries are a popular recreational area in part because of Yosemite National Park . There are many activities within the watershed , including boating , fishing , camping and hiking . Whitewater rafting is permitted throughout Merced River Canyon from the downstream half of Yosemite Valley to the entrance of Lake McClure . The most difficult rapids in this segment rate Class III and Class IV , mostly upstream of El Portal . There is also boating on Lake McClure . Camping throughout the upper Merced watershed is generally only permitted in designated campgrounds . Campgrounds along the Merced River and its tributaries include ones at Railroad Flat , McCabe Flat , Willow Placer , Merced Lake , Vogelsang Lake , Sunrise Creek , May Lake , Bridalveil Creek , and a ski hut at Ostrander Lake , the source of Bridalveil Creek . 
