Environmental Engineering Reference
In-Depth Information
With continuing problems from the overallocation of water resources of the Colorado
River, the U.S. Secretary of the Interior issued water shortage guidelines in 2007 for how
all the water rights of the river in a time of shortage will be managed.* A trigger point was
established on Lake Mead and water levels below this level trigger proportional reductions
by all of the Colorado River Basin states. This is the result of a river that has been overal-
located and has reached what Peter Glick terms “peak water” limit of the river capacity to
balance the river flow and the use of this resource. 8
26.8 Water Problems
Even with the massive public investment in dam construction in the Southwest, water is
still a problem for the hyperconsumption rate of growth experienced by the urban cen-
ters. In some circles, the mere existence of dams on the rivers is seen as detrimental to the
hydrologic cycle. Environmentalists argue that the natural flood cycle carried sediments
downstream to enrich the valleys with alluvial silt, which settles out in the area behind
the dam. The resulting water released downstream is clear and regular, not conducive to
any sedimentation or ecosystem health. The issue has been very controversial. In 1998,
then Secretary Bruce Babbit sanctioned a well-publicized release of water at Lake Mead
in an experiment on stream health. The debate continues between environmental activ-
ists concerned with the effects on the ecosystem health and biotic communities and those
seeking to manage the dam for utilitarian purposes of power and water delivery. For the
time being, the merits of dams are generally regarded as helpful to the human inhabitants
of the desert regions.
Tucson has struggled with water issues and public support for infrastructure develop-
ment. While the city of Tucson was able to add numerous wells from new water sources
along the Old Nogales Highway in 1954 and 1968, the result of this water mining caused
a massive die off of the extensive Mesquite bosques by the lowering of the groundwater
table in the area around the San Xavier del Bac mission. 9
With the construction of the San Juan Chama in New Mexico, a concern arose with the
impact of this project on a native fish called the silvery minnow. The habitat of this small
but ecologically significant fish was put in jeopardy by the completion of this project. There
are several ongoing legal and administrative actions pending over the division of water by
the San Juan Chama under the Endangered Species Act. The outcome of these claims by
the project may be years away from being resolved and may not ever satisfy either of the
concerned stakeholders of the project (Figure 26.11).
The Colorado River Compact, which was formed among western states in the 1920s, has
been under scrutiny as a shift in demographics has dramatically changed over the last 80
years. The state of Nevada, at the time of the compact, was a desolate place with little hope
of sustained development. In token, a paltry allotment of 300,000 ac ft a year was awarded
to the state, a small amount in comparison to Arizona's and California's share. Growth
of southwestern cities has added increased burdens on the infrastructure to support the
growing urban populations. Despite major water projects such as dams and canals, these
cities began to experience increased demands for water, causing the rapidly growing
municipalities to search for new solutions to managing water resources in the urban areas.
* http://www.usbr.gov/lc/region/programs/strategies.html (accessed January 20, 2012).
 
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