High Quality Content by WIKIPEDIA articles! Trabuco Creek (shown on federal maps as Arroyo Trabuco) is a small river in the U.S. state of California, flowing from the westernmost extreme of Riverside County through Orange County to join San Juan Creek in the city of San Juan Capistrano. 21.8 miles (35.1 km) long, its watershed covers 54 square miles (140 km2) in southeastern Orange County, including portions of three incorporated cities. Rising in a wild and undeveloped canyon in the southern Santa Ana Mountains, Trabuco Creek generally flows west and later south, and its upper and middle reaches are one of the few relatively undeveloped stretches of river of Orange County.