Headwaters rise on the west facing slopes of the inner coast southern Mayacamas Mountains, where the highest peaks are Hood Mountain, elevation 2750 feet (833 m) and Bald Mountain, elevation 2729 feet (826 m), each of which has views of the Pacific Ocean and the Sierra Nevada range. The headwaters cut through gorge and meadow of Sugarloaf Ridge State Park, which boasts 25 miles (40 kilometers) of self-guided trails and the Robert Ferguson Observatory. There is also a 25 foot (eight meter) high waterfall, present only when fed by the winter rains but can persist until late May for high rainfall years such as 2006. In the 100 foot (30 m) deep gorge into which the waterfall spills is a moist mixed forest habitat including California bay laurel, coast redwood, Douglas fir, big leaf maple, cherry holly, coffeeberry, and even tanbark oak. The understory features abundant ferns and boulder laden mosses. A prominent landform in this upper reach created by Sonoma Creek is Adobe Canyon. Locally part of this upper reach flow is sometimes called Adobe Creek. Tributaries near the headwaters include Mount Hood Creek and Graywood Creek.