Arroyo del Valle
Encyclopedia
Stream
A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...
in Alameda County
Alameda County, California
Alameda County is a county in the U.S. state of California. It occupies most of the East Bay region of the San Francisco Bay Area. As of the 2010 census it had a population of 1,510,271, making it the 7th most populous county in the state...
and Santa Clara County, California
Santa Clara County, California
Santa Clara County is a county located at the southern end of the San Francisco Bay Area in the U.S. state of California. As of 2010 it had a population of 1,781,642. The county seat is San Jose. The highly urbanized Santa Clara Valley within Santa Clara County is also known as Silicon Valley...
, USA, that is tributary to Arroyo de la Laguna
Arroyo de la Laguna
Arroyo de la Laguna is a southward-flowing stream in Alameda County, California, USA which originates at the confluences of South San Ramon Creek and Arroyo Mocho. The Arroyo de la Laguna is fed by tributaries in the Amador Valley and certain eastern slope drainages of the Diablo Range; these...
which in turn flows into Alameda Creek
Alameda Creek
Alameda Creek is a large perennial stream in the San Francisco Bay Area. The creek runs for from a lake northeast of Packard Ridge to the eastern shore San Francisco Bay by way of Niles Canyon and a flood control channel.-History:...
. The stream drains much of the southern portion of the city of Livermore
Livermore, California
Livermore is a city in Alameda County. The population as of 2010 was 80,968. Livermore is located on the eastern edge of California's San Francisco Bay Area....
, and it also flows through and drains a considerable fraction of the city of Pleasanton
Pleasanton, California
Pleasanton is a city in Alameda County, California, incorporated in 1894. It is a suburb in the San Francisco Bay Area located about east of Oakland, and west of Livermore. The population was 70,285 at the 2010 census. In 2005 and 2007, Pleasanton was ranked the wealthiest middle-sized city in...
. Water quality
Water quality
Water quality is the physical, chemical and biological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of standards against which...
measurements in this stream indicate a pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
level of 7.0, or neutral with respect to acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
ity; phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
levels were not detectable. In previous times the Arroyo del Valle had a significant steelhead migration; however, degradation of the stream in the latter half of the 20th century has decimated this anadromous fish population.
In the middle reaches of Arroyo del Valle south of Livermore, there has been considerable historic grazing
Grazing
Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...
use. Depth to groundwater in this reach of the watershed typically ranges from 50 feet (15 m) to 100 feet (30 m) and flows to the west. Subsequent to this reach, the Arroyo del Valle flows down the moderately sloping hills to enter gravel
Gravel
Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...
pits, where extraction (but not processing) has historically been conducted by Lone Star Industries.