The Mocho Subbasin is the largest of the

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated ...

subbasins in 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. Geography The valley is bound ...

watershed in Northern California. This subbasin is bounded to the west by the Livermore Fault Zone and to the east by the Tesla Fault. Some

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 A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams a ...

s in this unit include

Arroyo Valle Arroyo Valle or Arroyo Del Valle is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed March 15, 2011 westward-flowing stream that begins in northeastern Santa Clara County, California ...

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 zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. T ...

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 and

magnesium bicarbonate Magnesium bicarbonate or magnesium hydrogencarbonate, Magnesium, Mg(Hydrogen, HCarbonate, 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 ...

, However, the trend in adverse water quality due to

total dissolved solids Total dissolved solids (TDS) is a measure of the dissolved combined content of all inorganic and organic substances present in a liquid in molecular, ionized, or micro-granular ( colloidal sol) suspended form. TDS concentrations are often report ...

indicates un

potable Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ag ...

conditions may exist as early as 2020 due to

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

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 are ...

. 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