Ground Water Atlas of the United States -
Segment 1 California Nevada
Fresh Ground-Water Withdrawals
Water use in the valley has increased with a growth in agriculture and
population. During 1985, total ground-water withdrawals approximately equaled
the basinwide annual recharge of about 700,000 acre-feet. Water levels in the
upper basin have shown little decline because of minimal ground-water
development. Throughout the lower basin, however, agricultural and municipal
withdrawals caused a general decline until the mid-1950's. In 1956, the flow of
the Salinas River became perennial with the regulation of the Nacimiento River.
Ground-water levels ceased to decline from San Ardo to Gonzalez because the
increased streamflow maintained recharge to the ground-water system by seepage
from the river. In 1967, a second dam was completed on the San Antonio River and
helped to maintain the year-round flow of the river. Nonetheless, large and
increasing withdrawals near Monterey Bay downstream from the city of Salinas
have resulted in continued water-level declines, although availability of
surface-water recharge has increased. Water levels in wells in this area have
remained below sea level since the late 1940's and have resulted in saltwater
encroachment from Monterey Bay.
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