The Mocho Subbasin is the largest of the

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

subbasins in the

watershed Watershed may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, an area of land where surface water converges (North American usage) Music * Watershed Music Festival, an annual country ...

of the

Livermore Valley The Livermore Valley, historically known as the Valle de San José (Valley of San José), is a valley in Alameda County, California, located in the East Bay region. The city of Livermore is located in the valley. The valley became known as "Liver ...

Northern California Northern California (commonly shortened to NorCal) is a geocultural region that comprises the northern portion of the U.S. state of California, spanning the northernmost 48 of the state's List of counties in California, 58 counties. Northern Ca ...

. This subbasin is bounded to the west by the Livermore Fault Zone and to the east by the

Tesla Fault The Tesla Fault can be found in the northeastern Diablo Range, California. This fault is only semi-active. Geology This fault has been demonstrated to have a dextral offset of and is closely associated with the Greenville Fault. Mocho Subbas ...

. 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 Arroyo Mocho is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed March 15, 2011 stream which originates in the far northeastern corner of Santa Clara County and flows northwesterly into ...

channel across the Livermore Fault. Surface

watercourse A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...

s in this unit include Arroyo Valle and Arroyo Seco.

Aquifer details

To the north, the Tiago Macheira Subbasin contacts the Tassajara Formation, 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 The water table is the upper surface of the phreatic zone or zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, which may be fresh, saline, or brackish, depending on the loc ...

surface. Uncontained shallow groundwater occurs within of the surface, while deeper confined water has levels that occur at various depths from to below the surface.

Groundwater quality

Water quality Water quality refers to the chemical, physical, and biological characteristics of water based on the standards of its usage. It is most frequently used by reference to a set of standards against which compliance, generally achieved through tr ...

in the subbasin is generally fair with regard to

sodium bicarbonate Sodium bicarbonate ( IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda (or simply “bicarb” especially in the UK) is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cat ...

and

magnesium bicarbonate Magnesium bicarbonate or magnesium hydrogencarbonate, Mg( H CO3)2, is the bicarbonate salt of magnesium. It can be formed through the reaction of dilute solutions of carbonic acid (such as seltzer water) and magnesium hydroxide (milk of magnesia) ...

, However, the trend in adverse water quality due to

total dissolved solids Total dissolved solids (TDS) is a measure of the dissolved solids, dissolved combined content of all inorganic compound, inorganic and organic compound, organic substances present in a liquid in molecule, molecular, ionized, or micro-granular (so ...

indicates un

potable Drinking water or potable water is water that is safe for ingestion, either when drunk directly in liquid form or consumed indirectly through food preparation. It is often (but not always) supplied through taps, in which case it is also calle ...

conditions may exist as early as 2020 due to

overpopulation Overpopulation or overabundance is a state in which the population of a species is larger than the carrying capacity of its environment. This may be caused by increased birth rates, lowered mortality rates, reduced predation or large scale migr ...

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 Range The Diablo Range is a mountain range in the California Coast Ranges subdivision of the Pacific Coast Ranges in northern California, United States. It stretches from the eastern San Francisco Bay Area at its northern end to the Salinas Valley a ...

. In fact the name of the second segment of the Greenville 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.

External links

Groundwater bulletin

California Dept. of Water Resources website

References

Aquifers in California Bodies of water of Alameda County, California Livermore, California Livermore Valley Geology of Alameda County, California {{AlamedaCountyCA-geo-stub

Aquifer details

Groundwater quality

Geology

See also

External links

References