Here's the best dammed hike you'll find outside Yosemite Valley

The water was winning. Fed by the heaviest Sierra snowmelt in decades, it gushed down the narrow valley's walls and rushed across the trail in front of me. The bravest and most foolish hikers plunged on through, ice-cold whitewater up to their knees, a steep rocky drop below.

The rest of us paused — to think twice, and to drink in the scene. This was Yosemite National Park, but not the valley that most people visit.

Instead of Yosemite Valley, whose roads and parking lots have been choked with visitors for much of this summer, we were hiking the Hetch Hetchy Valley, a half-forgotten realm where the Tuolumne River was dammed in 1923 to feed San Francisco's thirst.

That project flooded some of John Muir's favorite Sierra scenery and many still mourn that loss. But the valley is still part of the park. Visitors can walk across the top of 100-year-old O'Shaughnessy Dam and hike along the edge of the reservoir via the 5-mile round-trip trail to Wapama Falls.

The hikers who want a stiffer challenge can keep going past Wapama (whitewater permitting) to try the 13-mile round-trip to Rancheria Falls. Those looking for something short and steep do the Lookout Point Trail or descend to the Tuolumne River and climb back up on the aptly named Poopenaut Valley Trail.

I focused on the Wapama Falls Trail. Granite walls?