Calleguas Creek

{{Short description|Creek in Ventura County, California, US}}

{{Use American English|date=February 2025}}

Calleguas Creek ({{IPAc-en|k|a:|'|j|eI|.|g|@|s}}; Chumash: Kayïwïsh, meaning "the head"){{cite book |last=Bright|first=William|author-link=William Bright|date=1998|title=1500 California Place Names: Their Origin and Meaning|location=Berkeley, CA|publisher=University of California Press}} is the terminus of a river system in Ventura County, California.{{cite gnis|240043|Calleguas Creek|16 January 2019}} It drains the Calleguas Creek Watershed, an area 30 miles long and 14 miles wide (343 square miles), which includes Simi Valley, Moorpark, Camarillo and a large portion of Thousand Oaks. Tributaries include Arroyo Simi, Arroyo Santa Rosa, Revolon Slough and Arroyo Conejo. It discharges into the Pacific Ocean, the Santa Barbara Channel, at Mugu Lagoon on Naval Base Ventura County, just north of Point Mugu, where the Santa Monica Mountains meet the ocean, marking the southern/eastern boundary of the Oxnard Plain.{{cite web|url=https://www.waterboards.ca.gov/rwqcb4/water_issues/programs/regional_program/Water_Quality_and_Watersheds/calleguas_creek_watershed/summary.shtml|title=CALLEGUAS CREEK WATERSHED|website=www.waterboards.ca.gov|access-date=31 December 2018}}

In 2009, Calleguas Creek was named the most polluted body of water in the jurisdiction of the Los Angeles Regional Water Quality Control Board.{{cite news|url=http://www.vcstar.com/news/calleguas-creek-among-most-polluted-ep-371498712-350733171.html|title=Calleguas Creek among most polluted|newspaper=Ventura County Star|date=July 22, 2009|access-date=31 December 2018}} Pollution along the river system has been an issue for decades.{{cite news|url=https://www.latimes.com/archives/la-xpm-1999-nov-16-me-34160-story.html|title=Calleguas Creek Study to Be Discussed|newspaper=Los Angeles Times|first=MARGARET|last=TALEV|date=November 16, 1999|access-date=31 December 2018}}{{cite news|url=https://www.latimes.com/archives/la-xpm-2002-feb-25-me-chloride25-story.html|title=No Easy Way Seen to Cut Creek's Salt|newspaper=Los Angeles Times|first=JENIFER|last=RAGLAND|date=February 25, 2002|access-date=31 December 2018}}{{cite web|date=April 25, 2005|title=Calleguas Creek Watershed Toxicity, Chlorpyrifos and Diazinon TMDL Technical Report|publisher=Los Angeles Regional Water Quality Control Board|url=https://lwa.com/wp-content/uploads/2015/06/TOX_6_Technical-Report.pdf}}{{cite web|url=https://www.researchgate.net/publication/11159897_Causes_of_toxicity_in_the_Calleguas_Creek_watershed_of_southern_California|title=(PDF) Causes of toxicity in the Calleguas Creek watershed of southern California|website=ResearchGate|access-date=31 December 2018}}