Wikipedia:Today's featured article/April 12, 2016

Aliso Creek is a 19 mi urban stream that runs through Orange County in the U.S. state of California from the Santa Ana Mountains to the Pacific Ocean, collecting seven main tributaries. It flows generally south-southwest through a narrow coastal watershed at the southern extreme of the arid Los Angeles Basin in a fairly straight course. Owing to the submersion of Southern California in the Pacific Ocean until 10 million years ago, the creek flows over marine sedimentary rock that dates from the late Eocene to the Pliocene. The watershed's broad sediment-filled valleys and deeply eroded side canyons were shaped by climate change during the last Ice Age. Historically, the creek served as the boundary between the Juaneño (Acjachemem) and Gabrieleño (Tongva) Indians. Although attempts to use the creek and its watershed as a municipal water source date to the early 20th century, the water it provided was erratic and of poor quality. The creek has become little more than an open wastewater drain, but the watershed supports some biodiversity, and remains a popular recreational area.