American River
The North Fork is the longest tributary of the American River, at . It begins at an elevation of about near Lake Tahoe in Placer County at Mountain Meadow Lake, just northeast of Granite Chief and immediately due west of Squaw Valley Ski Resort. It flows westward through remote wilderness areas.
Gualala River
The river has three forks: the South Fork, Wheatfield Fork and the North Fork. The South Fork is the longest and travels northwest, parallel to the coast along the San Andreas Fault rift zone. The Wheatfield Fork begins west of Lake Sonoma and has the largest flow of the three forks. Its tributaries include Tombs, Wolf, House, Haupt and Fuller creeks. Wheatfield is the first fork to combine with the South Fork. Buckeye Creek, a tributary of the river, joins the South Fork next. It is followed by Rockpile Creek and Big Pepperwod Creek. The North Fork is the only part of the river in Mendocino County. It travels roughly southwest towards the coast along the San Andreas Fault rift zone and meets the South Fork at the border between the counties, a few miles before the river flows into the ocean.