Santiago Creek - Course

Course

The main stem of Santiago Creek rises in the Cleveland National Forest, between Santiago Peak and Modjeska Peak, which together form the Saddleback formation. From there, the creek winds west-northwest for the first half of its course and southwest for the remaining half. It receives water from over five major tributaries and is free-flowing for most of the upper half of its course.

From the steep and narrow canyon between Santiago and Modjeska peaks, the creek runs south-southwest then turns sharply west, paralleling a ridge that separates it from the community of Portola Hills. It winds west-northwest, then after leaving the boundary of the national forest, it passes through the city of Modjeska and meets the first major tributary, Harding Canyon, from the right, 22 miles (35 km) from the mouth. As it continues bending northwards, Baker and Silverado creeks merge with Santiago Creek from the right. As the creek passes underneath Santiago Canyon Road, the canyon widens to a broad alluvial valley. The valley walls pull away and decrease in height as the creek begins to sink into the soft deposits and is almost dry by the time it reaches the second Santiago Canyon Road crossing. The creek then empties into Irvine Lake, which is also fed by Limestone Canyon, a left-bank tributary.

Santiago Creek then exits the Santiago Creek Dam, the dam forming Irvine Lake, 19 miles (31 km) from the mouth. The creek below the dam is initially an ephemeral watercourse due to diversions from the reservoir. Directly after leaving the dam the creek meets Fremont Canyon, a right bank tributary, and crosses underneath California State Route 241. It then flows northwest, bisecting Irvine Regional Park, and receives a tributary from Weir Canyon from the right. It then is dammed by the Villa Park Dam to form a flood control reservoir as it enters the city of the same name. The creek then flows in a flood control channel for the remaining 7 miles (11 km) of its course.

Flowing roughly southwest between the cities of Orange and Santa Ana, and after receiving Handy Creek from the left, the creek then crosses under California State Route 55 and 22, bisecting Hart Memorial Park and Santiago Creek Park in the process. The creek then crosses under Interstate 5 and continues west into the Santa Ana River. Its confluence is on the river's left bank, inside the Riverview Golf Course. About 10 miles (16 km) past the confluence with Santiago Creek, the Santa Ana River enters the Pacific Ocean.