• Length: 10 Miles
• Surface Area: 3,300 Acres
• Volume: 30,000 Acre Feet
• Drainage Area: 47 Square Miles
• Average Depth: 10 Feet
Lake Elsinore is a natural freshwater lake in Riverside County, California, located east of the Santa Ana Mountains and fed by the San Jacinto River. Originally named Laguna Grande by Spanish explorers, it was renamed for the town of Elsinore, established on its northeastern shore on April 9, 1888.
Lake Elsinore is the largest natural freshwater lake in Southern California. With its own 750 square mile watershed, it is situated at the lowest point within the San Jacinto River watershed of 750 sq mi, at the terminus of the San Jacinto River. It is the terminal lake of a partially closed basin called the San Jacinto Basin.
Lake levels are healthy at an average of 1,244 feet above sea level with a volume of 30,000 acre?ft that often fluctuates, although much has been done recently to prevent the lake from drying up, flooding, or becoming stagnant.
At 1,255 ft, the lake will spill into the outflow channel on its northeastern shore, known properly as Temescal Wash, flowing northwest through Temescal Canyon and feeding Alberhill Creek, which joins Temescal Creek, which in turn dumps into the Santa Ana River just northwest of Corona.
Lake Elsinore sits in a basin, the Elsinore Valley, a graben rift valley and part of the Elsinore Trough. It is the largest sag pond in the Elsinore Fault Zone. It lies beyond the northwestern extremity of the Temecula Valley, cut off from its Santa Margarita River watershed by a slight ridge running across the valley south of the lake between the Sedco Hills and the Elsinore Mountains to the west, part of the larger Santa Ana Mountain Range to the west and northwest of the valley.
On the west side of the lake are many small arroyos, such as the Lakeland Village Channel, which drains canyons whose source is on the east slope of the Elsinore Mountains. Lake Elsinore's northwestern shore rises to the foothills of the Santa Ana Mountains and the saddle between them and the Clevelin Hills, which closely enclose the lake along its northeastern shore until they decline and end short near the shore of the Temescal Creek outlet from the lake that passes through downtown Lake Elsinore. Two of its larger tributaries come into the north shore of the lake from the Santa Ana Mountains, Leach Canyon Creek, and McVicker Canyon Creek.
The lake south of the Temescal Creek outlet lies in an open area at the mouth of its major tributary, the San Jacinto River, distantly bounded to the east by the Tuscany Hills and south of the river by the Sedco Hills both part of the range of the Temescal Mountains. Much of lake basin has been cut off from the lake and river by a flood-control levee, which only permits the isolated section to fill after an extremely large rainfall event raises the lake over the level of the overflow spillway, north of the baseball stadium.
Lake Elsinore Valley, and the San Jacinto Basin that is its tributary, is a partially closed drainage basin, part of the Great Basin Divide. Its watershed is normally endorheic, but sometimes flows into the Santa Ana River watershed during periods of high water following heavy rainfall or snow melt. It discharges water through the Elsinore Spillway Channel outlet to Temescal Creek when the lake reaches the level of that outlet at 1,255 ft. Temescal Creek, flows through Warm Springs Valley and Walker Canyon into the Temescal Wash, which in turn flows through the northern Elsinore Trough to the Santa Ana River in such conditions. In recent years, efforts to maintain the lake at a stable high level have made these flows occur more frequently and for a longer duration during the year.