San Andrés Creek (''Spanish for'': St. Andrew's Creek), now called San Andreas Creek, is a perennial stream that flows
[ southeasterly along the ]San Andreas Fault
The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonics, tectonic boundary between the Pacific Plate and the North American Plate, and its motion is Fault (geology)#Strike-slip fau ...
from Sweeney Ridge
Sweeney Ridge, is a hilly hiking area of ridges and ravines between San Bruno, California, San Bruno and Pacifica, California, about a 25-minute drive south from San Francisco. The ridge's 1,200-foot-high summit, covered with coastal scrub and gra ...
in San Mateo County, California
San Mateo County ( ), officially the County of San Mateo, is a county (United States), county located in the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 764,442. Redwood City, California, Redwoo ...
, providing the inflow to and outflow from San Andreas Reservoir
San Andreas Lake is a reservoir adjacent to the San Francisco Peninsula cities of Millbrae and San Bruno in San Mateo County, California. It is situated directly on the San Andreas Fault, which is named after the valley it is in.
History
Afte ...
, and then entering Lower Crystal Springs Reservoir, where it was a historic tributary to San Mateo Creek. San Mateo Creek then carries its waters over Crystal Springs Dam
Crystal Springs Dam is a gravity dam constructed across the San Mateo Creek which is in San Mateo County, California. It impounds water to form the Lower Crystal Springs Reservoir which sits atop the San Andreas Fault in a rift valley created ...
northeast to San Francisco Bay
San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland.
San Francisco Bay drains water from a ...
.
History
After discovering San Francisco Bay from Sweeney Ridge
Sweeney Ridge, is a hilly hiking area of ridges and ravines between San Bruno, California, San Bruno and Pacifica, California, about a 25-minute drive south from San Francisco. The ridge's 1,200-foot-high summit, covered with coastal scrub and gra ...
on November 4, 1769, the Portolà expedition descended what Portolà called the ''Cañada de San Francisco'', now known as San Andreas Creek, to camp just south of the San Mateo Creek canyon on a lake called by him Laguna Grande, now covered by Upper Crystal Springs Reservoir. The campsite is marked by California Historical Marker No. 94 "Portola Expedition Camp". After heading south and descending from the foothills along San Francisquito Creek
San Francisquito Creek (Spanish for "Little San Francisco" - the "little" referring to size of the settlement compared to Mission San Francisco de Asís) is a creek that flows into southwest San Francisco Bay in California, United States. Histo ...
to established his base camp at El Palo Alto
El Palo Alto (Spanish language, Spanish: 'the tall stick') is a Sequoia sempervirens, coast redwood (''Sequoia sempervirens'') located on the banks of the San Francisquito Creek in Palo Alto, California, a city in the San Francisco Bay Area. The ...
, Portola retraced his steps and returned along San Andreas Creek to recross Sweeney Ridge and then via the coast back to San Diego
San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...
. The San Andres Creek place name is shown on the Rancho de las Pulgas
Rancho de las Pulgas was a 1795 Spanish land grant in present-day San Mateo County, California to José Darío Argüello. The literal translation is "Ranch of the Fleas", probably named after a village of the local Lamchin people. The grant wa ...
1856 plat map. Padre Palóu, on an expedition from Monterey to explore the western side of San Francisco Bay led by Captain Rivera, renamed Portola's ''Cañada de San Francisco'' to ''Cañada de San Andrés'' on November 30, 1774, it being the feast day of St. Andrew
Andrew the Apostle ( grc-koi, Ἀνδρέᾱς, Andréās ; la, Andrēās ; , syc, ܐܰܢܕ݁ܪܶܐܘܳܣ, ʾAnd’reʾwās), also called Saint Andrew, was an apostle of Jesus according to the New Testament. He is the brother of Simon Peter ...
. Captain Juan Bautista de Anza, after forging the first overland route from Monterey, California
Monterey (; es, Monterrey; Ohlone: ) is a city located in Monterey County on the southern edge of Monterey Bay on the U.S. state of California's Central Coast. Founded on June 3, 1770, it functioned as the capital of Alta California under bo ...
, to San Francisco Bay, explored the peninsula and selected the sites for Mission San Francisco de Asís
Mission San Francisco de Asís ( es, Misión San Francisco de Asís), commonly known as Mission Dolores (as it was founded near the Dolores creek), is a Spanish Californian mission and the oldest surviving structure in San Francisco. Located i ...
(''Mission Dolores'') and the Presidio of San Francisco
The Presidio of San Francisco (originally, El Presidio Real de San Francisco or The Royal Fortress of Saint Francis) is a park and former U.S. Army post on the northern tip of the San Francisco Peninsula in San Francisco, California, and is part o ...
. De Anza returned to Monterey via the Cañada de San Andrés and camped on the banks of San Mateo Creek on March 29, 1776. In de Anza's diary on March 29, 1776, he wrote: "Night having fallen, at a quarter past six I went down to the arroyo of San Andreas and to another, that of San Matheo, where it descends to empty into the estuary."
The two Crystal Springs lakes and San Andreas Lake used to be known as ''Spring Valley Lakes'' for the Spring Valley Water Company which owned them. The Spring Valley Water Company named the lakes, the Spring Valley Lakes, after the company. The original Spring Valley was between Mason and Taylor Streets, and Washington and Broadway Streets in San Francisco
San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...
, where the water company started. When the company went south for more water, the Spring Valley name was carried south too.
Watershed
San Andreas Creek's source elevation is at approximately on the eastern slopes of Sweeney Ridge
Sweeney Ridge, is a hilly hiking area of ridges and ravines between San Bruno, California, San Bruno and Pacifica, California, about a 25-minute drive south from San Francisco. The ridge's 1,200-foot-high summit, covered with coastal scrub and gra ...
from which it flows southeasterly along the San Andreas Rift
The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal). T ...
between Sweeney Ridge
Sweeney Ridge, is a hilly hiking area of ridges and ravines between San Bruno, California, San Bruno and Pacifica, California, about a 25-minute drive south from San Francisco. The ridge's 1,200-foot-high summit, covered with coastal scrub and gra ...
to the west and Buri Buri Ridge to the east, through San Andreas Reservoir
San Andreas Lake is a reservoir adjacent to the San Francisco Peninsula cities of Millbrae and San Bruno in San Mateo County, California. It is situated directly on the San Andreas Fault, which is named after the valley it is in.
History
Afte ...
, which was formed by the construction of a earth dam in 1868.[ The San Andreas Dam eliminates flow in the creek immediately below the dams, except for occasional spills or releases from the reservoir and seepage through the dam. From San Andreas Reservoir, the creek descends and enters the northeast arm of Lower Crystal Springs Reservoir. Historically San Andreas Creek joined San Mateo Creek just above the current location of the ]Crystal Springs Dam
Crystal Springs Dam is a gravity dam constructed across the San Mateo Creek which is in San Mateo County, California. It impounds water to form the Lower Crystal Springs Reservoir which sits atop the San Andreas Fault in a rift valley created ...
. The two Crystal Springs lakes and San Andreas Lake used to be known as ''Spring Valley Lakes'' for the Spring Valley Water Company, which owned them. Lower Crystal Springs Reservoir now covers the town of ''Crystal Springs'', which grew up around a resort of the same name.
Ecology
Fog drip
Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Reprint from Fog can be considered a type of low-lying cloud usually resembling stratus, and is heavily influe ...
may play a key role in the precipitation in the upper watershed. On Cahill Ridge (just west of San Mateo Creek and east of Pilarcitos Creek
Pilarcitos Creek (Spanish for: ''Little Pillars or Pillaries Creek'') is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed March 15, 2011 coastal stream in San Mateo County, California, ...
, at an elevation of , Oberlander measured fog drip beneath tanoak
''Notholithocarpus densiflorus'', commonly known as the tanoak or tanbark-oak, is a broadleaf tree in the family Fagaceae, and the type species of the genus ''Notholithocarpus''. It is native to the far western United States, particularly Oregon ...
(''Lithocarpus densiflorus''), Coast redwood and three Douglas fir trees, the latter tall. He found that the trees most exposed produced the most precipitation and in five weeks of measurement (July 20 – August 28, 1951) fog drip below the tanoak produced of precipitation, more than the total annual precipitation on nearby grasslands and chaparral. The Douglas fir produced of fog drip and appeared to provide unique conditions supporting the orchids giant helleborine (''Epipactis gigantea'') and phantom orchid (''Cephalanthera austiniae''), since these plants were found exclusively in these moist ridge tops.
See also
*List of watercourses in the San Francisco Bay Area
These watercourses (rivers, creeks, sloughs, etc.) in the San Francisco Bay Area are grouped according to the bodies of water they flow into. Tributaries are listed under the watercourses they feed, sorted by the elevation of the confluence so tha ...
*San Andreas Reservoir
San Andreas Lake is a reservoir adjacent to the San Francisco Peninsula cities of Millbrae and San Bruno in San Mateo County, California. It is situated directly on the San Andreas Fault, which is named after the valley it is in.
History
Afte ...
* San Mateo Creek
References
{{reflist
Rivers of San Mateo County, California
Santa Cruz Mountains
Rivers of Northern California
Tributaries of San Mateo Creek (San Francisco Bay Area)