The Santa Ana Mountains are a short peninsular mountain range along the coast of Southern California in the United States. They extend for approximately southeast of the Los Angeles Basin largely along the border between Orange and Riverside counties. Geography and climate Peaks and boundaries The range starts in the north at the Whittier Fault and Santa Ana Canyon, through which the Santa Ana River flows. To the north of the canyon are the smaller Chino Hills in Los Angeles and San Bernardino counties. The northernmost summit of the Santa Anas, at , is Sierra Peak. From there, the major summits are Pleasants Peak, ; Bedford Peak, ; and Bald Peak, . The next two peaks, Modjeska, ; and Santiago, , the highest summit in the range; form Saddleback Ridge. Saddleback, located approximately 20 mi (32 km) east of Santa Ana, is visible from much of Southern California. South of Saddleback are Trabuco Peak, ; Los Pinos Peak, and Sitton Peak, . Elsinore Peak, is included in a subrange called the Elsinore Mountains, which are west of Lake Elsinore. San Mateo Peak marks the highpoint of this range. Margarita Peak, ; and Redonda Mesa, are part of the Santa Margarita Mountains, a subrange of the Santa Anas that extends down to Camp Pendleton and Fallbrook. Southeast of the Elsinore Mountains is the Santa Rosa Plateau, named for the Rancho Santa Rosa that once encompassed it. At the south end of the plateau there is a steep escarpment from the basalt capped mesas that line it, that descends from about 500 feet at Mesa de Burro to Sandia Creek on the east to about 1800 feet at Avenaloca Mesa to De Luz Creek in the west. From the foot of the escarpment, the mountains and canyons of De Luz, Sandia Creek and others below it, run to the south to the Santa Margarita River. The range ends roughly at the Santa Margarita River. Much of the range is within the Trabuco Ranger District of the Cleveland National Forest, although some parts are still owned by two century-old ranches: the Irvine Ranch (originally known as the Yorba Family's Rancho Lomas de Santiago) and Rancho Mission Viejo (originally recorded as Rancho Misión Vieja). Waterways The Santa Anas include a number of high-mountain streams that flow for all or most of the year, although once out of the foothills these waterways are ephemeral. The