San Juan Creek is a major watercourse in Orange County, California, United States. The creek's watershed covers 133.9 square miles (346 km2), draining parts of the Santa Ana Mountains and the Cleveland National Forest. It begins in the southern part of the county, in the hot, arid Trabuco Canyon, and carries runoff from both the heavy winter rains and the light summer rains common to Southern California. The creek flows generally south-southwest before emptying into the Pacific Ocean at the city of Dana Point.
Its largest tributary, Trabuco Creek, joins it just north of San Juan Capistrano. Other significant tributaries include Hot Springs and Lion Creeks, also Bell Canyon.
The creek's environment includes coastal sage scrub, riparian woodland, wetlands, grassland, and coastal dunes. Its hard-bottomed stream bed is inhabited by numerous fish species, including the endangered southern steelhead trout.
