The Santa Ana River is the largest river entirely within Southern California in the United States. It rises in the San Bernardino Mountains and flows for most of its length through San Bernardino and Riverside counties, before cutting through the northern Santa Ana Mountains via Santa Ana Canyon and flowing southwest through urban Orange County to drain into the Pacific Ocean. The Santa Ana River is 96 miles (154 km) long, and its drainage basin is 2,650 square miles (6,900 km2) in size.
The Santa Ana Mountains are a short peninsular mountain range along the coast of Southern California in the United States. They extend for approximately 61 miles (98 km) southeast of the Los Angeles Basin largely along the border between Orange and Riverside counties.
The San Bernardino Mountains are a high and rugged mountain range in Southern California in the United States. Situated north and northeast of San Bernardino and spanning two California counties, the range tops out at 11,503 feet (3,506 m) at San Gorgonio Mountain – the tallest peak in Southern California. The San Bernardinos form a significant region of wilderness and are popular for hiking and skiing.
The Feather River is the principal tributary of the Sacramento River, in the Sacramento Valley of Northern California. The river's main stem is about 73 miles (117 km) long. Its length to its most distant headwater tributary is just over 210 miles (340 km). The main stem Feather River begins in Lake Oroville, where its four long tributary forks join—the South Fork, Middle Fork, North Fork, and West Branch Feather Rivers. These and other tributaries drain part of the northern Sierra Nevada, and the extreme southern Cascades, as well as a small portion of the Sacramento Valley. The total drainage basin is about 6,200 square miles (16,000 km2), with approximately 3,604 square miles (9,330 km2) above Lake Oroville.
Pyramid Lake is a reservoir formed by Pyramid Dam on Piru Creek in the eastern San Emigdio Mountains, near Castaic, Southern California. It is a part of the West Branch California Aqueduct, which is a part of the California State Water Project. Its water is fed by the system after being pumped up from the San Joaquin Valley and through the Tehachapi Mountains.
Diamond Valley Lake is a man-made off-stream reservoir located near Hemet, California, United States. It is one of the largest reservoirs in Southern California and one of the newest. It has a capacity of 800,000 acre-feet (990,000,000 m3). The lake nearly doubled the area's surface water storage capacity and provides additional water supplies for drought, peak summer, and emergency needs.
Lake Mathews is a large reservoir in Riverside County, California, located in the Cajalco Canyon in the foothills of the Temescal Mountains. It is the western terminus for the Colorado River Aqueduct that provides much of the water used by the cities and water districts of the Metropolitan Water District of Southern California (MWD). The reservoir is fenced and closed to all public access. The lake is near the Riverside community of Lake Hills, and is skirted by Cajalco Road on the south, El Sobrante Road on the north and east, and La Sierra Avenue on the west. La Sierra Avenue traverses the top of the west dike.
The Yuba River is a tributary of the Feather River in the Sierra Nevada and eastern Sacramento Valley, in the U.S. state of California. The main stem of the river is about 40 miles (64 km) long, and its headwaters are split into three major forks. The Yuba River proper is formed at the North Yuba and Middle Yuba rivers' confluence, with the South Yuba joining a short distance downstream. Measured to the head of the North Yuba River, the Yuba River is just over 100 miles (160 km) long.
The San Luis Rey River is a river in northern San Diego County, California.
The San Jacinto River is a 42-mile-long (68 km) river in Riverside County, California. The river's headwaters are in Santa Rosa and San Jacinto Mountains National Monument. The lower portion of the 765-square-mile (1,980 km2) watershed is urban and agricultural land. As a partially endorheic watershed that is contiguous with other Great Basin watersheds, the western side of the San Jacinto Basin is a portion of the Great Basin Divide.
The Sierra Pelona, also known as the Sierra Pelona Ridge or the Sierra Pelona Mountains, is a mountain ridge in the Transverse Ranges in Southern California. Located in northwest Los Angeles County, the ridge is bordered on the north by the San Andreas fault and lies within and is surrounded by the Angeles National Forest.
Skinner Reservoir, also known as Lake Skinner, is a reservoir in western Riverside County, California, located at the foot of Bachelor Mountain in the Auld Valley, approximately 10 miles (16 km) northeast of Temecula. It was created in 1973 by the construction of the Skinner Clearwell Dam on Tucalota Creek, and currently has a capacity of 44,200 acre-feet (54,500,000 m3). Located north of Rancho California Road near the Temecula Valley Wine Country, The address of the reservoir is: 37701 Warren Road, Temecula, CA 92592.
Temecula Creek, formerly known as the Temecula River, runs 32.6 miles (52.5 km) through southern Riverside County, California, United States, past the rural communities of Radec and Aguanga, and ending 0.5 miles (0.80 km) southeast of the original city center of Temecula. The creek is filled with boulders and is typically dry and sandy. It is a relatively undeveloped coastal-draining watershed. Until the 1920s, water flowed in Temecula Creek year-round.
The Domenigoni Mountains are a mountain range in Riverside County, California. They lie north of the Menifee Valley and south of the Perris Valley and San Jacinto Valley, west and north of Diamond Valley and north of Domenigoni Valley. The Domenigoni Mountains are composed primarily of metamorphic rock of the Triassic - Jurassic French Valley formation within Searls Ridge and the 1967 foot summit across the saddle to the west of it. The extreme eastern end of Searls Ridge and the western extreme of the 1967 foot summit of the range are Cretaceous granitic rock. The range and valley are named for Italian-American landowner Angelo Domenigoni, who purchased the land in 1879.
San Diego Creek is a 16-mile (26 km) urban waterway flowing into Upper Newport Bay in Orange County, California in the United States. Its watershed covers 112.2 square miles (291 km2) in parts of eight cities, including Irvine, Tustin, and Costa Mesa. From its headwaters in Laguna Woods the creek flows northwest to its confluence with Peters Canyon Wash, where it turns abruptly southwest towards the bay. Most of the creek has been converted to a concrete flood control channel, but it also provides important aquatic and riparian habitat along its course and its tidal estuary.
San Mateo Creek is a stream in Southern California in the United States, whose watershed mostly straddles the border of Orange and San Diego Counties. It is about 22 miles (35 km) long, flowing in a generally southwesterly direction. Draining a broad valley bounded by the Santa Ana Mountains and Santa Margarita Mountains, San Mateo Creek is notable for being one of the last unchannelized streams in Southern California.
Temescal Creek is an approximately 29-mile-long (47 km) watercourse in Riverside County, in the U.S. state of California. Flowing primarily in a northwestern direction, it connects Lake Elsinore with the Santa Ana River. It drains the eastern slopes of the Santa Ana Mountains on its left and on its right the western slopes of the Temescal Mountains along its length. With a drainage basin of about 1,000 square miles (2,600 km2), it is the largest tributary of the Santa Ana River, hydrologically connecting the 720-square-mile (1,900 km2) San Jacinto River and Lake Elsinore watersheds to the rest of the Santa Ana watershed. However, flowing through an arid rain shadow zone of the Santa Ana Mountains, and with diversion of ground water for human use, the creek today is ephemeral for most of its length, except for runoff from housing developments and agricultural return flows.
The Temescal Mountains, also known as the Sierra Temescal, are one of the northernmost mountain ranges of the Peninsular Ranges in western Riverside County, in Southern California in the United States. They extend for approximately 25 mi (40 km) southeast of the Santa Ana River east of the Elsinore Fault Zone to the Temecula Basin and form the western edge of the Perris Block.
The Perris Block is the central block of three major fault-bounded blocks of the northern part of the Peninsular Ranges. The Perris Block lies between the Santa Ana Block to the west and the San Jacinto Block to the east. The Perris Block, was named by Walter A. English in 1925 for the city of Perris, located near the center of the block.
The Plains of Leon are named for the former gold mining town, Leon once located near the middle of the plain. It is a plain in the Perris Block, contiguous on the south with the Perris Plain including within it the Domenigoni Valley and western Diamond Valley, French Valley, Auld Valley, the upper part of the valley of Warm Springs Creek and connecting tablelands.
