Calleguas Creek (;

Chumash Chumash may refer to: *Chumash (Judaism), a Hebrew word for the Pentateuch, used in Judaism *Chumash people, a Native American people of southern California *Chumashan languages, Indigenous languages of California See also

* Pentateuch (dis ...

: ''Kayïwïsh'', meaning "the head") is the terminus of a river system in

Ventura County, California Ventura County () is a County (United States), county located in Southern California, the southern part of the U.S. state of California. As of the 2020 United States census, 2020 census, the population was 843,843. The largest city is Oxnard, Ca ...

. It drains the Calleguas Creek Watershed, an area 30 miles long and 14 miles wide (343 square miles), which includes

Simi Valley Simi Valley (; Chumash: ''Shimiyi'') is a city in the valley of the same name in southeastern Ventura County, California, United States. It is from Downtown Los Angeles, making it part of the Greater Los Angeles Area. Simi Valley borders Th ...

, Moorpark,

Camarillo Camarillo ( ) is a city in Ventura County, California, United States. As of the 2020 United States census, the population was 70,741, an increase of 5,540 from the 65,201 counted in the 2010 Census. Camarillo is named for brothers Juan and ...

and a large portion of

Thousand Oaks Thousand Oaks is the second-largest city in Ventura County, California, located in the northwestern part of Greater Los Angeles. Approximately from the city of Los Angeles and from Downtown Los Angeles, it is named after the many oak trees pr ...

. Tributaries include

Arroyo Simi The Arroyo Simi (Spanish for "Small Stream of Simi", sometimes also referred to as Simi Creek) is a westwards-running creek, located in California, United States, running from the city of Simi Valley and crosses the valley from east to west, bef ...

, Arroyo Santa Rosa, Revolon Slough and

Arroyo Conejo Arroyo Conejo (Spanish for “Rabbit Creek”) carries part of the longest creek in the Conejo Valley which sprawls past the cities of Thousand Oaks and Camarillo, and the communities of Newbury Park, Casa Conejo and Santa Rosa Valley. Arroyo ...

. It discharges into the Pacific Ocean, the

Santa Barbara Channel The Santa Barbara Channel is a portion of the Southern California Bight and separates the mainland of California from the northern Channel Islands. It is generally south of the city of Santa Barbara, and west of the Oxnard Plain in Ventura Co ...

, at

Mugu Lagoon Mugu Lagoon (; Chumash: ''Muwu'', meaning "Beach") is a salt marsh located within the Naval Base Ventura County at the foot of the Santa Monica Mountains in Ventura County, California. The lagoon extends for 4.3 miles parallel to a narrow barrier ...

Naval Base Ventura County Naval Base Ventura County (NBVC) is a United States Navy base in Ventura County, California. Formed by the merger of Naval Air Station Point Mugu, NAS Point Mugu and Naval Construction Battalion Center Port Hueneme, CBC Port Hueneme, NBVC is a d ...

, just north of

Point Mugu Point Mugu (, Chumash: ''Muwu'') is a cape or promontory within Point Mugu State Park on the Pacific Coast in Ventura County, near the city of Port Hueneme and the city of Oxnard. The name is believed to be derived from the Chumash India ...

, where the

Santa Monica Mountains The Santa Monica Mountains are a coastal mountain range in Southern California, next to the Pacific Ocean. It is part of the Transverse Ranges. The Santa Monica Mountains National Recreation Area encompasses this mountain range. Because of its p ...

meet the ocean, marking the southern/eastern boundary of the

Oxnard Plain The Oxnard Plain is a large coastal plain in southwest Ventura County, California, United States surrounded by the mountains of the Transverse Ranges. The cities of Oxnard, Camarillo, Port Hueneme and much of Ventura as well as the unincorpo ...

. In 2009, Calleguas Creek was named the most polluted body of water in the jurisdiction of the Los Angeles Regional Water Quality Control Board. Pollution along the river system has been an issue for decades.

References

Rivers of Ventura County, California Camarillo, California Geography of Thousand Oaks, California Geography of Simi Valley, California Newbury Park, California Geography of Oxnard, California Moorpark, California Washes of California Santa Susana Mountains Simi Hills Canyons and gorges of California {{VenturaCountyCA-geo-stub