Santiago Creek is a prominent watercourse in Orange County, California, in the United States. It drains the majority of the northern Santa Ana Mountains and is a tributary of the Santa Ana River. It is one of the county’s most extensive watercourses. The creek gets its name from Santiago Peak, Orange County’s highest peak at 5,687 feet (1,733 meters), from whose slopes its sources rise.
The Santiago Creek basin in northern Orange County is approximately 100.6 square miles (261 km2). The top half of the creek is undeveloped, whereas the bottom section is developed and contains parts of Tustin, Orange, and Santa Ana. The creek is mostly channelized below the Villa Park Dam and only runs during major winter storms.
Historically, the Santiago Creek supplied water to the Tongva people, whose territory included much of northern Orange County and the Los Angeles Basin. For up to 12,000 years, Native Americans have lived in the Santiago Creek and Santa Ana River watersheds. The Spanish Gaspar de Portolá expedition of 1769 named the brook after crossing the Santa Ana River close where it crosses the Santiago Creek. There was a brief silver boom along the tributary Silverado Creek in the 1870s. The Santiago Dam was erected in 1929 to form Irvine Lake, which supplied irrigation water. Pipelines from Irvine Lake continue to supply a modest amount of water to the city of Villa Park.
Santiago Creek rises in the Cleveland National Forest, between Santiago Peak and Modjeska Peak, which create the iconic Santa Ana Mountains Saddleback. Before turning northwest, the creek travels south-southwest toward Portola Hills. Once out of the national forest, it flows through Modjeska before meeting the first major tributary, Harding Canyon Creek, on the right. It gets Baker and Silverado streams from the right as it flows downstream. The gorge opens to a broad alluvial plain after the first Santiago Canyon Road crossing, with the valley walls pulling out and decreasing in height. Except during the wet season of winter and early spring, the creek’s perennial surface flows are limited to this upper section; below here, the water runs underground.
Limestone Canyon, a left-bank tributary, also feeds Irvine Lake, which is fed by the creek. The Santiago Dam, located at the reservoir’s northern end, forms a 700-acre (280 ha) reservoir. Through a pipeline and cascade to Peters Canyon Reservoir, Irvine Lake supplies water to Villa Park and Orange. The creek below the dam is dry except during floods because the flume diverts the whole flow of the watercourse. The dry riverbed meets Fremont Canyon, a right bank tributary, below the dam and crosses below California State Route 241. It then flows northwest, cutting through Irvine Regional Park, before meeting Weir Canyon Creek on the right. The Villa Park Dam, located near Villa Park, serves as a flood control reservoir for Irvine Lake spills. For the next 7 miles (11 km) below Villa Park, the creek is limited to a flood control channel. It flows roughly southwest through the cities of Orange and Santa Ana, receiving Handy Creek on the left before crossing under California State Routes 55 and 22, passing through Hart Memorial Park and Santiago Creek Park. Because the stream is dry for the majority of the year, sections of the river bed are used as parking lots when conditions allow. The creek then runs beneath Interstate 5 and heads west toward the Santa Ana River. Its confluence lies on the left bank of the river, inside the Riverview Golf Course. The Santa Ana River joins the Pacific Ocean at Huntington Beach, about 10 miles (16 kilometers) below its confluence with Santiago Creek.
Next Point of Interest: Heritage Museum of Orange County