Santa Ana River

Santa Ana River Rio de los Temblores, Rio de Santa Anna
The Santa Ana River as seen from a small bluff overlooking the water. This part of the river serves as the border between Eastvale and Norco
Map of the Santa Ana River drainage basin
Location
Country	United States
State	California
Counties	San Bernardino, Riverside, Orange
Cities	San Bernardino, Riverside, Anaheim, Santa Ana
Physical characteristics
Source	Coon Creek
• coordinates	34°09′14″N 116°41′20″W / 34.15389°N 116.68889°W / 34.15389; -116.68889
• elevation	8,650 ft (2,640 m)
2nd source	Heart Bar Creek
• coordinates	34°08′06″N 116°44′23″W / 34.13500°N 116.73972°W / 34.13500; -116.73972
• elevation	7,900 ft (2,400 m)
Source confluence	San Bernardino Mountains
• location	Santa Ana Canyon, San Bernardino County
• coordinates	34°09′00″N 116°46′18″W / 34.15000°N 116.77167°W / 34.15000; -116.77167
• elevation	6,991 ft (2,131 m)
Mouth	Pacific Ocean
• location	Huntington Beach, Orange County
• coordinates	33°37′41″N 117°57′31″W / 33.62806°N 117.95861°W / 33.62806; -117.95861
• elevation	0 ft (0 m)
Length	96 mi (154 km), Northeast-Southwest
Basin size	2,650 sq mi (6,900 km2)
Discharge
• location	Below Prado Dam, near Corona[1][2]
• average	224 cu ft/s (6.3 m3/s)[3][2]
• minimum	0 cu ft/s (0 m3/s)
• maximum	317,000 cu ft/s (9,000 m3/s)
Basin features
Tributaries
• left	Mill Creek, San Timoteo Creek, Temescal Creek/ San Jacinto River, Santiago Creek
• right	Bear Creek, City Creek, Lytle Creek, Chino Creek

The Santa Ana River is the largest river entirely within Southern California in the United States.^[4] 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,^[5] and its drainage basin is 2,650 square miles (6,900 km²) in size.

The Santa Ana drainage basin has a diversity of terrain, ranging from high peaks of inland mountains in the north and east, to the hot, dry interior and semidesert basins of the Inland Empire, to the flat coastal plain of Orange County. Although it includes areas of alpine and highland forest, the majority of the watershed consists of arid desert and chaparral environments. Due to low regional rainfall, the river carries only a small flow except during the brief winter season, when it is prone to massive flash floods. The San Jacinto River, which drains the southern half of the watershed, rarely reaches the Santa Ana except in extremely wet years. A wide variety of animal and plant communities depend on the riparian zones and remnant wetlands along the Santa Ana River.

Humans have lived on the Santa Ana River for at least 9,000 years. The villages of Lupukngna, Genga, Pajbenga, Totpavit, and Hutuknga were located along the river.^[6][7] The river was first seen by Europeans in 1769, when it received its name from members of the Spanish Portola expedition. Because it was one of the only reliable sources of water in a wide region, many large ranchos developed along the river and one of its major tributaries, Santiago Creek. After the area became part of the United States, the economy transitioned to agriculture, before urbanizing in the 20th century. Many cities established during this time including Santa Ana, Riverside and Anaheim derived their names from the river. In order to protect urban areas from the river's flood threat, major channelization and damming projects were undertaken, resulting in the loss of much of the natural river channel.