Arroyo Grande Creek is a major stream in

San Luis Obispo County San Luis Obispo County (), officially the County of San Luis Obispo, is a county on the Central Coast of California. As of the 2020 United States census, the population was 282,424. The county seat is San Luis Obispo. Junípero Serra fou ...

on the Central Coast of

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. The creek flows in a southwesterly direction, from the

Santa Lucia Range The Santa Lucia Range (sæntə luˈsiːə) or Santa Lucia Mountains is a rugged mountain range in coastal Central California, running from Carmel southeast for to the Cuyama River in San Luis Obispo County. The range is never more than fro ...

to the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

. It is a major source of water supply for southern San Luis Obispo County. The creek's name is derived from the

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many countries in the Americas **Spanish cuisine **Spanish history **Spanish culture ...

for "large watercourse", and was sometimes called the "Roaring Grande" in the 19th century due to its propensity for flooding. The city of Arroyo Grande, established in 1867, was named after the stream.

Course

Arroyo Grande Creek begins in the southern foothills of the

, just outside the

Los Padres National Forest Los Padres National Forest is a United States national forest in Southern California, southern and central California. Administered by the United States Forest Service, Los Padres includes most of the mountainous land along the California coast ...

. It flows west through ranches and farms, and is joined by Saucelito Creek and Phoenix Creek from the left. The creek then flows into Lopez Lake, impounded by Lopez Dam about upstream from the mouth. Wittenberg and Lopez Canyon Creeks both originate in the Los Padres National Forest and flow into the lake from the north. The creek turns southwest below Lopez Dam, where it enters the Arroyo Grande Valley. It flows through Biddle Regional Park and is joined from the left by Tar Springs Creek, just above the city of Arroyo Grande. Los Berros Creek joins from the left just downstream of Arroyo Grande. After flowing through Arroyo Grande and

Oceano Oceano (Spanish: ''Océano'', meaning "Ocean") is a census-designated place (CDP) in San Luis Obispo County, California, United States. The population was 7,183 at the 2020 census, down from 7,286 at the 2010 census. Geography Oceano is locat ...

the creek empties into the Pacific Ocean at

Pismo State Beach Pismo State Beach is a beach on the Pacific Ocean, Pacific coast in the U.S. state of California. It is approximately 17 miles long and fronts the towns of Pismo Beach, Grover Beach, and Oceano in San Luis Obispo County, California, San Luis ...

, just north of the Pismo Dunes.

Watershed

The Arroyo Grande Creek watershed drains and is located wholly within San Luis Obispo County. Most of the watershed is hilly or mountainous, with wider valleys near the coast used for agriculture. Elevations range from sea level to in the upper reaches of Lopez Canyon. Principal vegetation communities are grassland, buckbrush and

chamise ''Adenostoma fasciculatum'', commonly known as chamise or greasewood, is a flowering plant native to California and Baja California. This shrub is one of the most widespread plants of the California chaparral ecoregion. Chamise produces a specia ...

chaparral Chaparral ( ) is a shrubland plant plant community, community found primarily in California, southern Oregon, and northern Baja California. It is shaped by a Mediterranean climate (mild wet winters and hot dry summers) and infrequent, high-intens ...

;

oak woodland An oak woodland is a plant community with a tree canopy dominated by oaks (''Quercus spp.''). In terms of canopy closure, oak woodlands are intermediate between oak savanna, which is more open, and oak forest, which is more closed. Although the c ...

occurs along streams and valleys. The average annual rainfall is .

River modifications

Lopez Dam was built in 1968 by the San Luis Obispo County Flood Control and Water Conservation District, to provide drinking water for communities in the "Five Cities" area including the city of Arroyo Grande. Its reservoir, Lopez Lake, can store almost . The annual water yield of is divided with approximately 52 percent going to local water agencies and 48 percent reserved for downstream releases. Lopez Dam is a total barrier to fish migration, and has contributed to the decline of

steelhead Steelhead, or occasionally steelhead trout, is the Fish migration#Classification, anadromous form of the coastal rainbow trout or Columbia River redband trout (''O. m. gairdneri'', also called redband steelhead). Steelhead are native to cold-wa ...

populations in the creek. Due to chronic flooding, the lower of Arroyo Grande Creek were channelized in 1959. Parts of tributaries, including Tar Springs and Los Berros Creeks, have also been channelized. Floodgates were installed to control water flow between Arroyo Grande Creek and Meadow Creek, a remainder of the once extensive coastal marsh system, in order to protect nearby homes.

References

{{Authority control Rivers of San Luis Obispo County, California

Course

Watershed

River modifications

See also

References