MANAGEMENT BRINGS A NEW ENVIRONMENTAL APPROACH
by Whit Gibbons
October 30, 2005
I visited one of the unchallenged seven natural wonders of the world-the
Grand Canyon. Standing on the cliff edge and looking at the Bright Angel
Trail below was breathtaking the first time I saw it a half century ago.
It still is. The panorama of red, yellow, and brown rocks forming the
ten-mile-wide gorge is as awesome as ever. From one vantage point you
can see a short stretch of the Colorado River, literally a mile below,
the source of the millions of years of erosion that formed the canyon.
day I attended a conference in Phoenix listening to scientists, government
officials, power company executives, conservation groups, recreational
tour companies, and others discuss and debate the best uses of the river
and the canyon. From the perspective of an easterner, or for that matter
almost anyone who is not directly involved, deciding how to "manage"
such an ecosystem might seem like an ideal example of a nonproblem. Why
would a 1,400-mile-long river passing through a canyon with exposed Precambrian
rocks more than two billion years old need any help managing itself?
all natural systems today, adding people to the equation has caused the
dilemma. The Colorado River provides water for millions of people from
Wyoming to southern California. Two dams generate hydroelectric power,
serving communities living over thousands of square miles. Anglers fish
along hundreds of miles of river, while water enthusiasts take rafting
tours through rocks and rapids. Along with bird-watchers and hikers, they
camp along the river. The general public simply enjoys the views and wildlife,
and most want the canyon ecosystem to be as natural as possible.
and environmental impacts to the Colorado River include one above and
one below Grand Canyon National Park. Hoover Dam was completed in 1935
to form Lake Mead along the southern Arizona and Nevada border. The 1963
construction of Glen Canyon Dam in northern Arizona created Lake Powell.
At this point no one is going to be 100 percent satisfied with the handling
of the Colorado River ecosystem. The Glen Canyon Dam Adaptive Management
Program may come closest to a plan that might work.
management is a process designed to deal with the disparate opinions of
how to manage an ecosystem. In this case, the power generated by the Glen
Canyon hydroelectric dam depends on regulating the amount of water released
from the reservoir, which changes downstream flow rates and water levels.
The basic idea of adaptive management is for scientists to conduct research
to determine how dam operations are affecting the river environment and
its use by people. Subsequently, science-based decisions can be made to
modify future operations.
conference one report noted that the use of campsites and sandbars for
recreational purposes has declined since dam construction, presumably
because of reduced river flows and loss of sand deposits downstream. A
2004 test of a high flow release demonstrated that beaches and sandbars
were rebuilt. One response in the adaptive management process would be
to modify flow rates in a manner that would assure occasional high flow
releases to reestablish river sandbars and encourage recreational camping.
conflicting situations arise. Commercial power interests would prefer
to adjust river flows daily to achieve the most economically efficient
rates and would not view excessively high flows as economically practical.
Also the river would not be navigable for recreational rafting during
high flows. On the other hand, some native fish populations, including
the endangered humpback chub, have declined since dam construction. Some
ecologists believe that creating the more natural situation of occasional
high flows might benefit the chub and other fishes. Such flows would also
reduce the number of rainbow and brown trout, neither of which is native
to the Colorado River. Trout eat native fish, so are unpopular with some
naturalists. But nonnative trout also support a sports fishing industry,
making them very popular with anglers.
management may become the only viable approach for ecosystems whose management
affects many people and many kinds of activity. The Everglades, Great
Lakes, and certain coastal areas come to mind. The forthcoming environmental
and economic deliberations about the Glen Canyon Dam will be instructive.
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