Arroyo Valle

{{Use American English|date=February 2025}} {{Infobox river | name = Arroyo Valle | name_native = | name_native_lang = | name_other = Arroyo De Los Taunamines | name_etymology =  | image = Arroyo-del-Valle-MCB.jpg | image_caption = Arroyo del Valle in [[Pleasanton, California]] | image_size = 300 | map = Arroyo Valle watesrhed.jpg | map_size = 300 | map_caption = Arroyo Valle watershed ([https://mghydro.com/watersheds/shared/D826B8.html Interactive map]) | pushpin_map = | pushpin_map_size = | pushpin_map_caption=  | subdivision_type1 = Country | subdivision_name1 = [[United States]] | subdivision_type2 = State | subdivision_name2 = [[California]] | subdivision_type3 = Region | subdivision_name3 = [[Santa Clara County, California|Santa Clara County]] | subdivision_type4 = | subdivision_name4 = | subdivision_type5 = City | subdivision_name5 = [[Pleasanton, California]]  | length = | width_min = | width_avg = | width_max = | depth_min = | depth_avg = | depth_max = | discharge1_location= | discharge1_min = | discharge1_avg = | discharge1_max =  | source1 = Confluence of [[San Antonio Creek (Santa Clara County)|San Antonio Creek]] and [[Arroyo Bayo]] | source1_location = | source1_coordinates= {{coord|37|23|08|N|121|34|21|W|display=inline}}<ref name=gnis>{{cite gnis|232367|Arroyo Valle}}</ref> | source1_elevation = {{convert|1808|ft|abbr=on}} | mouth = Confluence with [[Arroyo de la Laguna]] | mouth_location = | mouth_coordinates = {{coord|37|39|43|N|121|54|22|W|display=inline,title}}<ref name=gnis/> | mouth_elevation = {{convert|302|ft|abbr=on}}<ref name=gnis/> | progression = Arroyo Valle > Arroyo de la Laguna > Alameda Creek > San Francisco Bay > Pacific Ocean | river_system = | basin_size = {{convert|430|km2|abbr=on}} | tributaries_left = Pino Creek, Sycamore Creek (Santa Clara County), Trout Creek (Santa Clara County) | tributaries_right = Spring Canyon Creek, [[Sulphur Gulch (Arroyo Valle tributary)|Sulphur Gulch]], Colorado Creek, [[Dry Creek (Arroyo Valle tributary)|Dry Creek]], Eylar Canyon Creek, Lang Canyon Creek | custom_label = | custom_data = | extra = }}

'''Arroyo Valle''' or '''Arroyo Del Valle'''<ref>{{gnis|255060|Arroyo Valle}}</ref> is a {{convert|36.4|mi|km|adj=mid|-long}}<ref name=NHD>U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. [http://viewer.nationalmap.gov/viewer/ The National Map] {{webarchive |url=https://web.archive.org/web/20120329155652/http://viewer.nationalmap.gov/viewer/ |date=2012-03-29 }}, accessed March 15, 2011</ref> westward-flowing [[stream]] that begins in northeastern [[Santa Clara County, California]], and flows northwesterly into [[Alameda County, California|Alameda County]] where it is dammed to form [[Lake Del Valle]]. After that Arroyo Valle is a tributary to [[Arroyo de la Laguna]] which in turn flows into [[Alameda Creek]] and thence to [[San Francisco Bay]]. In the past, the Arroyo Valle had a significant [[Rainbow trout|steelhead]] migration; however, degradation of the stream in the latter half of the 20th century has decimated this [[anadromous]] fish population.<ref>[http://pleasanton.k12.ca.us/avhsweb/thiel/creek/index.html Arroyo del Valle Creekwatch] {{webarchive |url=https://web.archive.org/web/20160303180220/http://pleasanton.k12.ca.us/avhsweb/thiel/creek/index.html |date=March 3, 2016 }}</ref>

==History== Arroyo Valle was also once known as '''Arroyo De Los Taunamines''' (Stream of the Taunamines), for the [[Costanoan]] Taunamines people who lived there. In 1853 it was renamed Arroyo del Valle (Stream of the Valley).<ref>{{cite book |title=Alameda County Place Names |author=Page Mosier |author2=Dan Mosier |name-list-style=amp |location=Fremont, California |publisher=Mines Road Books |year=1986 |page=12 |isbn=978-1-889064-02-4 |url=https://books.google.com/books?id=JRkSAQAAIAAJ |access-date=March 12, 2016 }}</ref>

==Watershed and Course== The Arroyo Valle watershed drains {{convert|147|sqmi|km2}}.<ref name=Trout/> The upper reaches of Arroyo Valle stretch into northeastern [[Santa Clara County]] where the mainstem is formed by the confluence of [[San Antonio Creek (Santa Clara County)|San Antonio Creek]] and [[Arroyo Bayo]].<ref>{{cite gnis|218394|Arroyo Bayo}}</ref> San Antonio Creek's origin is on the western slope of {{convert|3804|ft}} [[Mount Stakes]], west of the Santa Clara-[[Stanislaus County]] border, about {{convert|32|mi}} southeast of [[Livermore, California|Livermore]]. San Antonio Creek traverses the [[San Antonio Valley, California|San Antonio Valley]] as it heads west to Arroyo Valle. Arroyo Bayo also has its origin on Mount Stakes southwestern slope and traverses Upper San Antonio Valley as it also heads west to Arroyo Valle.

Arroyo Valle is dammed by the Del Valle Dam, which forms the reservoir [[Lake Del Valle]] in southeastern [[Alameda County]].

Downstream from the reservoir, Arroyo Valle drains much of the southern portion of the city of [[Livermore, California|Livermore]], and it also flows through and drains a considerable fraction of the city of [[Pleasanton, California|Pleasanton]], both in the [[Livermore Valley]]. The stream is a tributary to [[Arroyo de la Laguna]], which is in turn tributary to [[Alameda Creek]], which ultimately reaches San Francisco Bay at [[Fremont, California]].

==Ecology== [[Water quality]] measurements in Arroyo Valle in the Livermore Valley indicate a [[pH]] level of 7.0, or neutral with respect to [[acid]]ity; [[phosphate]] levels were not detectable.<ref>[http://www.pleasanton.k12.ca.us/amador/creek/projects/Bio99/JJM/exp.html Water Quality Testing in Arroyo del Valle] {{webarchive |url=https://web.archive.org/web/20050309101321/http://www.pleasanton.k12.ca.us/amador/creek/projects/Bio99/JJM/exp.html |date=March 9, 2005 }}</ref>

In the middle reaches of Arroyo Valle south of Livermore, there has been considerable historic [[grazing]] use. Depth to groundwater in this reach of the watershed typically ranges from {{convert|50|ft|m|0}} to {{convert|100|ft|m|0}} and flows to the west.<ref>''Environmental Site Assessment, Murdell Lane, Unincorporated Alameda County'', EMI Report 10202, September 29, 1989</ref> Subsequent to this reach, the Arroyo del Valle flows down the moderately sloping hills to enter [[gravel]] pits, where extraction (but not processing) has historically been conducted by [[Lone Star Industries]].

Historically, Arroyo Valle was connected to [[Tulare Lake (Alameda County)|Tulare Lake]], a lagoon in the Livermore-Amador Valley, and thus to the Alameda Creek watershed. There are historical records of [[steelhead trout]] (''Oncorhynchus mykiss'') in Arroyo Valle although now the Lake Del Valle Dam is an impassable barrier to spawning runs.<ref name=Trout>{{cite report |title=Evaluation of the Potential Historical and Current Occurrence of Steelhead within the Livermore-Amador Valley |author=Charles H. Hanson |author2=Janet Sowers |author3=Allen Pastron |date=August 2004 |publisher=Alameda County Flood Control and Water Conservation District - Zone 7 |url=https://www.alamedacreek.org/reports-educational/pdf/Zone%207%202004.pdf |access-date=April 30, 2021}}</ref>

==See also== *[[List of watercourses in the San Francisco Bay Area]] *[[Arroyo de la Laguna]] *[[Alameda Creek]]

==References== {{reflist}}

==External links== * [http://museumca.org/creeks/133B09-OMAValle.html Arroyo Valle northern watershed map] at Oakland Museum of California * [https://waterdata.usgs.gov/nwis/uv?site_no=11176500 Current conditions for Arroyo Valle] at US Geological Survey; shows current and historical gage height, discharge rate, and temperature

[[Category:Rivers of Alameda County, California]] [[Category:Rivers of Santa Clara County, California]] [[Category:Tributaries of Alameda Creek]] [[Category:Diablo Range]] [[Category:Livermore Valley]] [[Category:Livermore, California]] [[Category:Geography of Pleasanton, California]] [[Category:Rivers of Northern California]]