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Central Valley California; A
transformed landscape
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The central valley of
California, prior to transformation, is described as having been an
"American Serengeti". The two major rivers, the San Joaquin and
Sacramento, and their many tributaries from the Sierra Nevada flooded
annually, depositing rich alluvial soils and creating vast wetlands.
The streams were habitat for prolific salmon runs, the marshes home for
immense flocks of waterfowl, the grasslands home for herds of Tulle
Elk. It is estimated that thousands of Grizzly bears inhabited the
valley.
Now the only bears to be seen are on the state flag.
The rivers have been dammed, the land leveled, the seasonal flood waters
held back to be distributed throughout the valley as irrigation waters.
The region has been transformed into one of the worlds great
agricultural districts. The economic benifits are inarguable, so
is the loss of habitat. |
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A few areas
remain where it is possible to get a glimpse of what the valley must
have looked like prior to its agricultural transformation. Here,
in the San Luis National Wildlife Refuge large wetlands with native
tulle reeds provide sanctuary for migrating waterfowl. The
adjacent Kesterson area is infamous for having had water poisoned by
runoff from irrigation projects.
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Historically, the
transformation of the valley began with the mining operations following
he gold rush. Here, miles of stream valley still show the effects
of dredging for gold. Elsewhere, hydraulic mining stripped topsoil
from areas in the foothills and led to silting up of channels and
flooding in the valley. Some of California's first environmental
legislation was aimed at curbing these mining practices. |
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The San Luis
reservoir is the lynch pin of the irrigation system on the western side
of the central valley. Water from the north is stored here during
periods of high discharge, to be released throughout the summer.
Nearly all of the water enters and leaves through the canals. |
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The
Nature Conservancy works to protect land through outright purchase and
also working with local landowners and communities. We visited the
Consumnes Preserve, where levees have been breached in places to allow a
more natural flooding cycle. Here students hear about the benefits
of this program, which include groundwater recharge and increased health
of out-migrating salmon smolt. |
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Next: The
Sierra Nevada and Mono Lake
For more information, contact Dr. Tim Lincoln, Institute for
the Study of the Environment, Albion College, Albion MI 49224.
Phone (517) 629-0486 – e-mail tlincoln@albion.edu
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