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Of course, prodigious volumes of water are necessary to sustain a modern population.
(It requires, for instance, nearly 3000 gallons of water to produce the food
for a typical family dinner, according to a "Facts Brochure," issued
by the Utah Water Supply Internet site.) The water supply must serve, not
only individuals, but also agricultural and livestock enterprises, municipalities,
businesses and industries. Indeed, 80 or 90 percent of the total consumption
in agricultural areas may be attributable to irrigation alone. As a result of
the relentless growth in demand, said the USGS, our "Ground-water resources
in the Southwest [have become] among the most overused in the United States."
Complicating an already difficult situation, much of our underground water
lies beyond practicable reach. For example, in New Mexico, said Alletta Belin,
Consuelo Bokum and Frank Titus, Decision-Maker's Field Guide 2003, the deposits
may be "spread widely in small volumes in limited aquifers, remote locales,
fluctuating (therefore unreliable) volumes, at great (therefore uneconomic) depths,
of marginal quality, or [the water] is present in other situations that make
it unavailable for other than local or small-scale use."
Within a typical aquifer, only part of the total supply may be accessible
at all. Much of it, especially that in the deeper and more dense strata, may
lie beyond reasonable reach, even with our modern "high-capacity large-diameter
drilled wells with turbine pumps." Moreover, water, especially from the
deeper strata, may be saturated with minerals that render it unfit for use unless
it passes through expensive treatment processes.
As water tables fall, rainfall, snowmelt and, in some instances, irrigation
and treated waste waters help recharge aquifers, but through processes and at
rates that have not been fully investigated by scientists. "The quantity
of ground-water recharge to alluvial basins in the Southwest is one of the least
known factors in the water budget," said the USGS in "Desert Basins
of the Southwest."
As a consequence, the interaction of ground water and surface water has become
the central focus of an important USGS program for evaluating aquifers in the
Southwest. "Major study components," said the USGS, "include
(1) regional synthesis; (2) effects of climate variability on recharge to and
discharge from ground-water systems; (3) effects of development of ground-water
resources on sustainability of riparian [i.e., streamside or lakeside] systems;
(4) development of improved methods of estimating recharge to desert basins;
and (5) development of improved methods of simulating interaction of ground water
and surface water in arid and semi-arid regions."
Hopefully, data from the study will help agencies develop effective underpinnings
for managing the use of our ground waters. "We cannot continue [in New
Mexico] to mine our ground water at current rates," said Belin, Bokum and
Titus. That observation likely applies to most of the Southwest, where ground
water withdrawals increased by more than 50 percent during the last half of the
20th century, according to the USGS report Water-Use Trends in the Desert Southwest—1950-200,
by A. D. Konieczki and J. A. Heilman.
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