San Bernardino Mountains The Whitewater River has three significant tributaries: the North, Middle, and South Forks, all within the
Sand to Snow National Monument. The North Fork begins in the
subalpine zone at about on
San Gorgonio Mountain and descends steeply southeast to the Middle Fork, which flows east through a wide
arroyo. The South Fork flows northeast through a narrower wooded
canyon, joining the Middle Fork lower down. The upper watershed is in the
San Gorgonio Wilderness and
San Bernardino National Forest, then it reaches land managed by the
Bureau of Land Management. Below the confluences, the arroyo is at least wide, paved with accumulations of boulders, gravel, and sand brought down by floods and brushy except in stream channels cleared by floodwaters. Due to floods and shifting channels, there is almost no
riparian forest development, except locally along unnamed minor tributaries with relatively stable channels. The
Pacific Crest Trail (PCT) enters the arroyo from the north and follows it downstream through Whitewater Canyon. A connecting trail links the PCT to the
Whitewater Preserve, which serves as one of the primary public access points to this section of the river. A small population of wild but non-native
Rainbow trout occurs locally in shaded reaches or cooler tributaries, but elevated summer temperatures limit their distribution along most of the stream. Floods and debris flows periodically reshape the Whitewater Canyon section of the river. During the Valentine’s Day storm of February 2019 and again during
Hurricane Hilary in August 2023, flooding damaged sections of Whitewater Canyon Road and affected access and trails in the canyon. In contrast to the dry washes commonly visible in the Coachella Valley, the Whitewater River often flows above ground in the upper canyon of the San Bernardino Mountains, where it supports informal recreation such as hiking, wading, and wildlife viewing. Sections of the Whitewater River were designated as part of the
National Wild and Scenic Rivers System in 2019. During rare floods, surface water may reach the
endorheic basin of the
Salton Sea, below
sea level. ==Popular culture==