Santiago Creek is a major watercourse in Orange County in the U.S. state of California. About long, it drains most of the northern Santa Ana Mountains and is a tributary to the Santa Ana River. It is one of the longest watercourses entirely within the county.San Juan Creek is approximately the same length, and the Santa Ana River is not entirely within Orange County. The creek shares its name with Santiago Peak, at the highest point in Orange County, on whose slopes its headwaters rise.
