Mocho Subbasin
Encyclopedia
The Mocho Subbasin is the largest of the groundwater
subbasins in the Livermore Valley
watershed
. This subbasin is bounded to the west by the Livermore Fault Zone and to the east by the Tesla Fault
. Some groundwater
flow occurs across these fault boundaries, but flows are discontinuous below a depth of fifty feet across the Tesla Fault
and south of the Arroyo Mocho
channel across the Livermore Fault. Surface watercourse
s in this unit include Arroyo del Valle
and Arroyo Seco
.
, with which no groundwater exchange occurs. Groundwater flow in the subbasin is generally from southeast toward the northwest or north, corresponding to the slope of the regional terrain and water table
surface. Uncontained shallow groundwater occurs within 25 feet (8 m) of the surface, while deeper confined water has levels that occur at various depths from 75 feet (22.9 m) to 150 feet (45.7 m) below the surface.
in the subbasin is generally fair with regard to sodium bicarbonate
and magnesium bicarbonate, However, the trend in adverse water quality due to total dissolved solids
indicates unpotable
conditions may exist as early as 2020 due to overpopulation
of the Livermore-Amador Valley by humans and associated discharge of salts to the groundwater.
. In fact the name of the second segment of the Greenvile Fault (starting from north to south) is the Arroyo Mocho Segment. The Arroyo Mocho Segment is generally considered to be more well developed and not as youthful as traces delineating the Marsh Creek-Greenville Segment, for example.
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
subbasins in the Livermore Valley
Livermore Valley
The Livermore Valley AVA is an American Viticultural Area in Alameda County, California, surrounding the city of Livermore in the Tri-Valley region. Both the AVA and the city are named after Robert Livermore, a landowner whose holdings encompassed the valley. The groundwater basin underlying the...
watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
. This subbasin is bounded to the west by the Livermore Fault Zone and to the east by the Tesla Fault
Tesla Fault
The Tesla Fault is a seismically active geological fault structure associated with the Diablo Range in the vicinity of the Livermore Valley in Contra Costa County, California.-Geology:...
. Some groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
flow occurs across these fault boundaries, but flows are discontinuous below a depth of fifty feet across the Tesla Fault
Tesla Fault
The Tesla Fault is a seismically active geological fault structure associated with the Diablo Range in the vicinity of the Livermore Valley in Contra Costa County, California.-Geology:...
and south of the Arroyo Mocho
Arroyo Mocho
Arroyo Mocho is a stream in eastern Alameda County, California that traverses the cities of Livermore and Pleasanton.The underlying aquifer is the Mocho Subbasin, whose eastern boundary is the Tesla Fault...
channel across the Livermore Fault. Surface watercourse
Watercourse
A watercourse is any flowing body of water. These include rivers, streams, anabranches, and so forth.-See also:* physical geography* Environmental flow* Waterway* Hydrology* Wadi-External links:...
s in this unit include Arroyo del Valle
Arroyo del Valle
Arroyo del Valle or Arroyo Valle is a westward-flowing stream in Alameda County and Santa Clara County, California, USA, that is tributary to Arroyo de la Laguna which in turn flows into Alameda Creek. The stream drains much of the southern portion of the city of Livermore, and it also flows...
and Arroyo Seco
Arroyo Seco (Alameda County)
Arroyo Seco is an watercourse in Alameda County, California, that traverses through the city of Livermore. Arroyo Seco means "dry stream" in Spanish. Arroyo Seco lies above the Arroyo Seco watershed, which includes the eastern part of the city of Livermore and also the Lawrence Livermore...
.
Aquifer details
To the north, the Tiago Macheira Subbasin contacts the Tassajara FormationTassajara Formation
The Tassajara Formation is a geologic unit within the Livermore Valley of Northern California, USA. The formation surfaces only in the northern upland parts of the Livermore Valley and underlie the central part of the valley floor at a depth ranging from to...
, with which no groundwater exchange occurs. Groundwater flow in the subbasin is generally from southeast toward the northwest or north, corresponding to the slope of the regional terrain and water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...
surface. Uncontained shallow groundwater occurs within 25 feet (8 m) of the surface, while deeper confined water has levels that occur at various depths from 75 feet (22.9 m) to 150 feet (45.7 m) below the surface.
Groundwater quality
Water qualityWater 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...
in the subbasin is generally fair with regard to sodium bicarbonate
Sodium bicarbonate
Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na HCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda . The natural mineral form is...
and magnesium bicarbonate, However, the trend in adverse water quality due to total dissolved solids
Total dissolved solids
Total Dissolved Solids is a measure of the combined content of all inorganic and organic substances contained in a liquid in: molecular, ionized or micro-granular suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a sieve...
indicates unpotable
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
conditions may exist as early as 2020 due to overpopulation
Overpopulation
Overpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. The term often refers to the relationship between the human population and its environment, the Earth...
of the Livermore-Amador Valley by humans and associated discharge of salts to the groundwater.
Geology
This subbasin is in the vicinity of the seismically active Greenville Fault associated with the Diablo RangeDiablo Range
The Diablo Range is a mountain range in the California Coast Ranges subdivision of the Pacific Coast Ranges. It is located in the eastern San Francisco Bay area south to the Salinas Valley area of northern California, the United States.-Geography:...
. In fact the name of the second segment of the Greenvile Fault (starting from north to south) is the Arroyo Mocho Segment. The Arroyo Mocho Segment is generally considered to be more well developed and not as youthful as traces delineating the Marsh Creek-Greenville Segment, for example.
See also
- Bishop SubbasinBishop SubbasinThe Bishop Subbasin is an aquifer that resides between two subsurface structures of the Tassajara Formation in the northern extremity of the Amador Valley. This aquifer is a sub-unit of the Livermore-Amador Groundwater Basin. The Bishop Subbasin is associated with the locale of San Ramon,...
- Hacienda Business ParkHacienda Business ParkHacienda Business Park is a 900 acre mixed used job center and housing development in Pleasanton, California.-History:Approved in 1982 and ratified by Pleasanton voters in 1983, the business park covers approximately 20 square blocks and features many multi-story office buildings and headquarters...
- Niles ConeNiles ConeThe Niles Cone is a groundwater basin in Alameda County, California, USA which is the source of drinking water for a sizeable human urban population in the East Bay. The land area corresponding to this groundwater basin is approximately 103 square miles; the Niles Cone Basin is bounded on the...
- groundwater basin in Alameda County. - Bernal SubbasinBernal SubbasinThe Bernal Subbasin is an aquifer located in the southwestern corner of Livermore Valley Groundwater Basin, Alameda County, California, USA. All of the groundwater in Livermore Valley moves toward the Bernal Subbasin, which is bounded on the east by Pleasanton Fault, on the north by the Park...
- aquifer in the Livermore Valley.