San Tomas Aquino Creek
|San Tomas Aquinas Creek|
|Arroyo de San Tomás Aquinas, San Tomas Aquino Creek|
|Region||Santa Clara County|
|- left||Wildcat Creek (California), Saratoga Creek|
|- right||Mistletoe Creek, Smith Creek (Santa Clara County, California)|
|Cities||Saratoga, Monte Sereno, Los Gatos, Campbell, Santa Clara, San Jose|
|Source||El Sereno Summit in the Santa Cruz Mountains|
|- location||Saratoga, California|
|- elevation||2,400 ft (732 m)|
|Mouth||Guadalupe Slough in South San Francisco Bay|
|- location||Sunnyvale, California|
|- elevation||13 ft (4 m) |
San Tomas Aquinas Creek, known locally as San Tomas Aquino Creek, is a 16.5-mile-long (26.6 km) stream that heads on El Sereno mountain in El Sereno Open Space Preserve in Saratoga, California in Santa Clara County, California, United States. It flows north through the cities of Saratoga, Monte Sereno, Los Gatos, Campbell, Santa Clara and San Jose before its confluence with the Guadalupe Slough in south San Francisco Bay.
In the 1850s the creek appeared on several land grant maps as San Tomas Aquinas Creek and Arroyo de San Tomás Aquinas. Historically, San Tomas Aquino Creek formed the eastern boundary of the 1841 Rancho Quito and the western boundary of the 1840 Rancho Rinconada de Los Gatos land grants.
Watershed and Course 
The San Tomas Aquinas Creek watershed drains 44.8 square miles. The major tributaries of San Tomas Aquino Creek include (heading downstream) Mistletoe, Wildcat (and its Vasona sub-tributary), Smith and Saratoga Creeks. Of these, Saratoga Creek is the largest tributary and joins San Tomas Aquino Creek south of Highway 101, near Monroe Street. Due to its relatively large size, the Saratoga Creek subwatershed is often viewed as a distinct watershed even though it does not directly discharge to the Lower South San Francisco Bay. In fact, San Tomas Aquino Creek used to be a tributary of Saratoga Creek and thence to the Guadalupe River, but when the latter was redirected from Guadalupe Slough to Alviso Slough to facilitate navigation, San Tomas Aquino Creek was extended directly to Guadalupe Slough at Sunnyvale Baylands Park in Sunnyvale and Saratoga Creek became tributary to San Tomas Aquino Creek.
The middle portion of the creek runs under or alongside San Tomas Expressway. At Cabrillo avenue it starts running under the median of the expressway until Williams Road. Some portions are partially exposed, but much is completely underground. From Williams road it runs along the west side of the expressway until Bucknall road. From there it leaves the expressway and enters the hills.
The San Tomas Aquino bike trail follows the creek from the bay to Cabrillo avenue.
Habitat and wildlife 
In 1898 John Otterbein Snyder collected steelhead trout (then Salmo irideus Gibbons) specimens in Campbell Creek (now Saratoga Creek, a tributary of San Tomas Aquino Creek). A 1985 California Department of Fish and Game (CDFG) survey of Saratoga Creek noted "a major steelhead and king salmon spawning area" on San Tomas Aquino Creek located approximately 200 yards downstream of the Saratoga and San Tomas Aquino creeks confluence. Rainbow trout (Oncorhynchus mykiss), the landlocked form of steelhead trout persist in the Saratoga Creek watershed but anadromous steelhead cannot run up from the Bay because of a barrier at the confluence of San Tomas Aquino Creek and Saratoga Creek that prevents their passage upstream. Recent genetic analysis has shown that the San Tomas Aquino watershed trout are of native origin and not hatchery stock.
Leidy (2007) identified the native fishes in San Tomas Aquino Creek as Hitch (Lavinia exilicauda), California roach (Lavinia symmetricus), Sacramento sucker (Catostomus occidentalis occidentalis), Three-spined stickleback (Gasterosteus aculeatus), Rainbow trout (Oncohrynchus mykiss) and possibly Chinook salmon (Oncorhynchus tshawytscha). Although the latter had been considered now absent from the watershed, in mid-October, 1996, Roger Castillo, the founder of the Salmon and Steelhead Restoration Group, recovered a giant Chinook salmon from San Tomas Aquino Creek beneath Highway 237 (see photo). Rainbow trout are the landlocked form of steelhead trout. Non-native fishes include Common carp (Cyprinus carpio), Goldfish (Carassius auratus auratus), Golden shiner (Notemigonus crysoleucas), and Western mosquitofish (Gambusia affinis).
See also 
- "El Sereno Summit". Geographic Names Information System, U.S. Geological Survey.
- U.S. Geological Survey Geographic Names Information System: San Tomas Aquinas Creek
- U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National Map, accessed August 25, 2011
- Durham, David L. (1998). California's Geographic Names: A Gazetteer of Historic and Modern Names of the State. Word Dancer Press. pp. page 699. ISBN 1-884995-14-4.
- Erwin Gustav Gudde (1974). California Place Names. University of California Press. p. 350. Retrieved 2011-08-25.
- Mildred Brooke Hoover, Douglas E. Kyle (2002). Historic spots in California. Stanford University Press. p. 661. ISBN 978-0-8047-4482-9. Retrieved 2011-08-29.
- "San Tomas Aquino Watershed". Santa Clara Valley Urban Runoff Pollution Prevention Program (SCVURPPP). Retrieved 2011-08-25.
- "Middle Guadalupe Slough Watershed Map". Oakland Museum. Retrieved 2011-08-25.
- "Lower Guadalupe Slough Watershed Map". Oakland Museum. Retrieved 2011-08-25.
- Historical Atlas of Santa Clara County California. San Francisco, California: Thompson & West. 1876.
- John Otterbein Snyder, United States Bureau of Fisheries (1905). Notes on the fishes of the streams flowing into San Francisco Bay, California in Report of the Commissioner of Fisheries to the Secretary of Commerce and Labor for the fiscal year ending June 30, 1904 30. General Printing Office. p. 337. Retrieved 2011-08-25.
- Robert A. Leidy, Gordon Becker, Brett N. Harvey (2005). Historical Distribution and Current Status of Steelhead/Rainbow Trout (Oncorhynchus mykiss) in Streams of the San Francisco Estuary, California (Report). Center for Ecosystem Management and Restoration. pp. 117-118. http://www.cemar.org/pdf/santaclara.pdf. Retrieved 2011-08-25.
- John Carlos Garza, Devon Pearse (2008-03). Population genetics of Oncorhynchus mykiss in the Santa Clara Valley Region, Final Report to the Santa Clara Valley Water District (Report). Santa Clara Valley Water District. pp. 1-54.
- Robert A. Leidy (2007-04). Ecology, Assemblage Structure, Distribution, and Status of Fishes in Streams Tributary to the San Francisco Estuary, California (Report). San Francisco Estuary Institute. p. 178. http://legacy.sfei.org/leidy_No530/. Retrieved 2011-08-24.
- Guadalupe Slough Watershed maps page at Guide to San Francisco Bay Area Creeks
- Santa Clara County Creeks Coalition
- Santa Clara Basin Watershed Management Initiative (SCBWMI)
- Salmon and Steelhead Restoration Group