Ground Water Atlas of the United States -
Segment 1 California Nevada
Fresh Ground-Water use and management
During the early years of ground-water development in the coastal basins, from
the 1850's to early 1900's, the principal use of water was for irrigated
agriculture. Although agricultural ground-water use remains substantial,
urbanization has gradually replaced most agricultural land in the larger basins
and the greatest collective ground-water demand is now for public supply. The
largest water users are cities and suburbs from San Francisco southward, but
because of the unequal distribution of rainfall, most of the freshwater is in
northern California. Accordingly, it has become necessary to regulate streamflow
and import water into many coastal basins from the Sierra Nevada, the Colorado
River, the Owens Valley, and northern California through an extensive system of
aqueducts.
For many years, rapidly growing populations in several basins resulted in
ground-water withdrawals that exceeded natural recharge on a long-term basis;
this led to marked water-level declines. The consequences of these excessive
withdrawals ranged from mild, such as increased pumping costs, to severe, such
as land subsidence and seawater intrusion. Today (1995), ground water in the
coastal basins of California is carefully managed. The current supply of water
from all sources, including imported water, approximately balances demand.
However, because the natural recharge to many basins, especially southward from
the San Francisco Bay area, is far less than the volume of ground water
currently (1995) withdrawn, increases in population will require either
additional imports, more conservation, an increase in the amount of water now
reclaimed, or a combination of all three. More than any other environmental
factor, water availability will likely determine the size of the population
these basins can support.
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to "EUREKA AREA BASIN"
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