Environmental Engineering Reference
In-Depth Information
For example, says Gleick, “if runoff decreases in the Colorado
River even 10 percent due to climate change—which is perfectly
plausible—and we don't change the way we operate the river, the
big reservoirs like Lake Mead and Lake Powell go dry very quickly.”
Adding to the stress on water supplies, “we have actually given away
more water on the Colorado than it looks like nature will provide,”
says Gleick. “It's like a bank account where more [water, in this
case] is going out than coming in. Pretty soon, your bank balance
[or your reservoir level] dries up. You can't operate the system for
the long term if you're spending more than is coming in.”
Adding to the Colorado River's woes, a new study has found
that dark-colored dust settling on the snow in the Upper Colorado
River Basin robs the river of 5 percent of its water on average every
year, and has been doing that to some extent since Europeans set-
tled the West in the 1850s! The dust, caused by grazing, off-road
vehicles, construction, and other soil disturbances, absorbs the sun-
light, accelerates the snowmelt, and leads to earlier plant growth,
and greater evaporation and transpiration.
The amount of water lost in the Colorado is nearly twice what
the city of Las Vegas uses in a year, according to study co-author Brad
Udall, director of the Western Water Assessment, a joint program of
the Cooperative Institute for Research in Environmental Sciences,
a collaboration of the University of Colorado and NOAA. “By cut-
ting down on dust we could restore some of the lost fl ow, which is
critical as the Southwestern climate warms,” Udall said when the
study was released in September 2010. It also was published in the
Proceedings of the National Academy of Sciences,
and funded by the
National Science Foundation, the National Aeronautics and Space
Administration and the Western Water Assessment.
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However, says Udall, cleaning up the dust won't solve Las Vegas's
or the Colorado River's overuse and overallocation problems. “Say
we're losing 5 percent of the water. In a perfect world, we could pre-
vent 50 percent of that loss, which is more or less what Las Vegas
uses in a year. But the overuse problems in the Colorado River basin
won't be solved by restoring this relatively small amount of water.”
There are numerous causes of the overuse, adds Udall, and
the problems are shared by the Lower Basin states of Arizona,
California, and Nevada. Population growth, climate change, outdated
