Santa Ana River
The Santa Ana River rises within the San Bernardino Mountains and most of the length travels through Riverside County and San Bernardino county, then goes through northern Santa Ana Mountains. It also travels through Orange County before finally reaching the Pacific Ocean. The entire river is 96 miles in length, with a 2,650 sq. mile drainage basin.
There are various types of terrain at the Santa Ana drainage basin, which ranges from higher peaks in the north and east of inland mountains, to dry and hot interior with semi-desert basins within Inland Empire. Most of the watershed is comprised of chaparral and desert environments, but there are some regions of highland and alpine forests. With the exception of brief winter seasons, the river has a small flow due to the lack of rainfall in the area. However, during the winter season flash floods are common.
Research has shown that people have lived on the Santa Ana River for 9,000 years, possibly longer. There is evidence that four different indigenous groups lived along the river prior, and during the European colonization. In 1769, Europeans initially seen the river, providing it the name originating from Spanish Portola expedition members.
The river was among the only sources of reliable water in the area, resulting in ranchos being developed by the river. Once the region became part of the U.S, local economy had transitioned into an agricultural region prior to urbanizing during the 20th century. There were various cities established at this period, including Riverside, Anaheim, and Santa Ana, which were named after the river. In the 20th century, projects including damming and channelization were conducted to redirect flood threats, which caused much loss for the rivers natural channel.
Rising in the San Bernardino mountains, the Santa Ana river begins as two small streams, Coon Creek and Heart Bar Creek. Meanwhile, the highest source of the river is Dollar Lake, and Dry Lake which are both located in northern San Gorgonio Mountains, the headwater for the Santa Ana river’s south fork.
From this, the river continues to flow west by a heavily forested mountain valley that is roughly 18 miles from the headwaters, receiving the initial major tributary known as Bear Creek at the north. Water flows into Bear Creek by Big Bear Lake, a well-known recreational lake.
Turning south, the river passes throughout the Seven Oaks Dam, until it flows into the Inland Empire, including Riverside County and San Bernardino County. Mill Creek reaches the river from the south, and City Creek flows into the river from the north, while San Timoteo Creek reaches the river in the south.
The river bed is often dry from the Mill Creek stretch due to ground water recharge, while year-round flow is restored by a Riverside water treatment plant. The river supports riparian zones between Riverside and Prado Dam, providing a considerable amount of greenery.