San Juan Canyon
San Juan Creek is a creek in Orange County in the U.S. state of California. It is about 29 miles (47 km) long, and along with its major tributary, Trabuco Creek, drains 133 square miles (340 km2) near the southernmost extent of Orange County. This article describes the course of San Juan Creek.
San Juan Creek begins in the southern Santa Ana Mountains, a few miles northwest of Lake Elsinore. Its highest elevation is 5,100 feet (1,600 m) above sea level. Paralleling the Ortega Highway (California State Route 74) the creek flows erratically south, west and occasionally northwest. In the furthest upper reaches of the watershed, the creek is typically ephemeral. The creek channel in the uppermost few miles is a narrow mountain stream with many rapids and waterfalls, which include a series of large 5-to-15-foot (1.5 to 4.6 m) cascades, known as San Juan Falls. There are little alluvial deposits in the canyons, and the creek mostly cascades over bedrock. In this upper reach, the pool-and-riffle stream channel structure is evident. There are a few developments within the area, but most of the canyon is too narrow for development, and the only major structure that influences the creek throughout San Juan Canyon is Ortega Highway, which follows the course of the entire canyon.
Leaving its uppermost headwaters, San Juan Creek flows south and west in several meanders, then finally proceeds to flow west-southwest. It is joined by the ephemeral watercourses Long Canyon and Morell Canyon on the right bank, and Bear Canyon on the left bank. At about this reach, it plunges over San Juan Falls, a 15-foot (4.6 m) drop; the falls is preceded by a short cascade and followed by a series of near-vertical falls. In this reach, stream pools, which tend to become stagnant during low flow periods, are abundant. Continuing on down the gradually widening valley, San Juan Creek turns westwards and drops over several more falls, before finally widening to about 330 feet (100 m). Just below the falls, a small perennial watercourse trickles into San Juan Creek on the left bank.
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