Bell Canyon is a major drainage on the west side of the Santa Ana Mountains in southern Orange County, with Bell Creek flowing about 14.4 miles to San Juan Creek as the watershed’s second largest tributary after Trabuco Creek. Much of the canyon remains undeveloped within protected public lands, and its broad, deep alluvial valley preserves a largely natural braided watercourse and riparian woodland. Its landscape records ancient rock formations, mountain uplift, and floodplain building during the Wisconsinian glaciation. Human presence reaches back nearly 10,000 years, from the Juaneño or Acagchemem through the rancho era to Starr Ranch, while recent restoration has reduced polluted urban runoff from nearby development.