Lewis's Monkeyflower - Erythranthe lewisii
Particularly common above 5,000 feet where it forms large clumps alongside streams and other wet habitats; also behaving in a "weedy" manner in roadside ditches. Photographed (left) on the Skyline Trail at the Paradise River crossing on August 29, 2014, (center) by the river at the White River Campground on June 29, 2016, and (right) at the Carter Falls trailhead on June 10, 2014.