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The U.S. Department of the Interior has discovered a way to produce more water from the overworked Colorado River. Before I proceed, I need to point out that I learned of this, not from my own dogged journalistic investigations, but from Phil Doe of Littleton, who chairs a group of troublemakers known as the Citizens Progressive Alliance.
At issue last summer was a pipeline from the San Juan
River to serve Gallup, N.M., and portions of the Navajo
nation. Before it can be built, the Interior Department has
to issue a Hydrologic Determination
that there will
likely be enough water available to make the project worth
building. After all, there's no point in constructing 267
miles of pipeline if there's no water to put into the
pipes.
On June 8, Interior Secretary Dirk Kempthorne sent a
letter to Bill Richardson, governor of New Mexico. In it,
Kempthorne wrote that The finding in the Determination
that there is likely to be sufficient water to support the
proposed contract,
which removes any Department of
Interior concern about potential limitations of water
supply.
The San Juan River is a major tributary of the Colorado River, which is governed by the Colorado River Compact. The compact was drawn up in 1922, and it was based on the best data available then, which indicated an average annual flow in the Colorado of about 17 million acre-feet.
The problem is that those statistics were compiled during years that, in the grand sweep of things, were unusually wet. More recent studies, based on tree rings and extending back for centuries, put the average closer to 13.5 million acre0feet per year.
So we have a river that was allocated on the basis of 17
million annual acre feet, but rarely carries that much
water. In our state's water jargon, the river is
over-appropriated
-- there are more legitimate
claims on the river than it has water to supply.
And that was before this pipeline was approved by
Interior. So how did Interior determine that there is
likely to be sufficient water
?
Take two logical statements, combine them into illogic, and you can make water, at least if you're the Interior Department.
Logical Statement 1: The lower the evaporation from the surface of reservoirs in the Colorado River basin, the more liquid water in the system. No argument there.
Logical Statement 2: The lower the levels of the reservoirs in the Colorado River basin, the less surface area there is to suffer from evaporation. As reservoirs shrink down from their side canyons, of course the surface area will diminish, as anyone who's been to Powell Reservoir in the past five years can attest.
So, the reservoirs are smaller and thus they lose less water, and therefore, there is more water available. Believe it or not, that's how our Interior Department determined that there was water available for this New Mexico pipeline.
No one seems to have asked Why are the reservoirs
smaller?
The answer to that question would be something
like Years of drought,
and that would imply that
there isn't enough water to go around with current uses,
let alone adding another diversion from the river.
But hey, who are we to argue with the experts at the Bureau of Reclamation and the Interior Department? They've shown us the way to put more water in the Colorado River.
Consider Lake Mead behind Hoover Dam near Las Vegas. That's hot, dry country, and so the reservoir drops 6.4 feet a year on account of evaporation, which works out to 791,000 acre-feet a year -- enough water for more than 3 million people.
Move up the Colorado River to Powell Reservoir, also in a hot desert, and there's an estimated 884,000 acre-feet a year lost to evaporation and seepage into the surrounding sandstone. Let's figure only half the loss is evaporation, and that's 442,000 acre-feet -- enough for at least 1.7 million people.
In other words, the combined evaporative loss from just these two reservoirs is enough water for all 4.7 million of us Coloradans. And there are many more evaporation-tank reservoirs along the Colorado River and its tributaries.
So if we were to remove the dams, the reservoirs would shrink away and evaporation losses would diminish. Thus there's more water for everybody in our arid West. So if it works this way, as Interior now argues, why did it build dams in the first place?
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