I enjoyed Paolo Bacigalupi’s story, "The Tamarisk Hunter." (HCN, 6/26/06: The Tamarisk Hunter) It was a good piece of science fiction and intriguing thinking as well. But I need to make a correction to Greg Hanscom’s thinking in his editorial. The Upper Basin states are NOT obligated to deliver an average of 7.5 million acre-feet of Colorado River water to the Lower Basin each year "no matter what."
If the Upper Basin states have used up the water they have in storage (in Lake Powell, Flaming Gorge, Blue Mesa and Navajo reservoirs, etc.), the delivery requirements work backwards through the Upper Basin water claims, shutting them off, one by one, from now back to the water rights granted in 1922 — and then they STOP. The Colorado River Compact, negotiated in 1922, is specifically structured to apply to water rights claimed only after that date. This means, for example, that much of the fruit orchard irrigation in the Grand Valley (in western Colorado) is safe from the compact even in a severe drought, because it has priority dates in the 1800s.
In contrast, much of the water that is diverted to the Front Range cities and farms by water projects (Colorado Big Thompson, Dillon Reservoir, Twin Lakes, etc.) post-dates the Compact. So a lot of the effect of "Big Daddy Drought" would be felt on the Front Range. There are also some Western Slope projects that date from later than 1922, including a goodly portion of many boomtowns’ municipal water supplies.
Now, this might result in those cities buying up the senior orchard water rights and diverting that water for their own use within Colorado, but it wouldn’t get the water to California just because of the Compact. Only if California’s political power proved to be enough to rewrite the Compact in its favor could the implied scenario in the editorial come about. Hasn’t happened — yet.
THE EDITOR REPLIES
Peter Sartucci is right — as right as anyone can be on a matter as speculative as this. Intrigued by his letter, I called water wonks Westwide to see if I could get a clearer picture of what might happen if California and the other Lower Basin states (Nevada and Arizona) made a "call" on the Colorado River under the Colorado River Compact. The answer, almost without exception, was something like, "That’s a damn good question." In the words of Chuck Brendecke, president of the Boulder consulting firm Hydrosphere, "It’s a rock that nobody has wanted to turn over. It’s a potentially scary prospect."
The basic scenario would likely play out just as Sartucci has suggested. Water managers in the Upper Basin (Wyoming, Utah, Colorado, New Mexico) would work back through the list of priority rights, shutting people off until they got to the rights that pre-date the Colorado River Compact; these rights are known in water circles as "present perfected rights." Seems straightforward enough — assuming the states have such a list (not all of them do), assuming that they can agree on when the compact went into effect (they can’t), and assuming they can agree on how much the Upper Basin owes (a treaty with Mexico and other factors make even that a bone of contention). Suffice it to say that water lawyers would have a heyday.
Whatever the system, the rationing would be dramatic: The Upper Basin currently uses roughly twice as much Colorado River water as it has present perfected rights to. According to Hydrosphere, users in the Upper Basin have present perfected rights to about 2 million acre-feet of water. They currently use about 4 million acre-feet. The difference, 2 million acre-feet, is enough to supply roughly 4 million homes. And the gap is only widening. By 2060, Upper Basin states are projected to use 6 million acre-feet from the Colorado. The more their populations grow, the more vulnerable they become.
And, as Sartucci says, cities would generally lose their water first. In New Mexico, the San Juan-Chama diversion project, which sucks roughly 100,000 acre-feet of Colorado River water each year, would be shut off immediately. Too bad for the city of Albuquerque, which is building a $172 million water treatment plant so that it can pump that water into homes, after discovering that its groundwater supply is dwindling. A call under the compact would slash Colorado River Diversions to Colorado’s Front Range from about 481,000 acre-feet down to about 71,700 acre-feet — a reduction of 85 percent, according to Hydrosphere. That water currently supplies Denver, Boulder, Broomfield, Loveland, Golden, Englewood and Colorado Springs, to name a few.
Of course, the Front Range cities have Eastern Slope water as well, and groundwater (though there, as in Albuquerque, the supply has been diminished). Cities like Aurora have been buying up senior rights from farmers. And in dry times, cities can buy or lease more from farmers, who currently use at least 80 percent of the water in the Upper Basin.
There’s another mitigating factor: The 7.5 million acre-feet that the Upper Basin states are required to deliver to the Lower Basin is actually a running average of 75 million acre-feet over 10 years. Even during the recent drought, far more than 7.5 million acre-feet a year has been reaching the Lower Basin, giving the Upper Basin states more than 25 million acre-feet of extra credit over the past 10 years. In times of serious shortage, the Upper Basin would be required to drain its biggest savings account, Lake Powell, to make its deliveries. After that, however, it could deliver less than 7.5 million acre-feet each year for a few years, hanging on to the water in its other reservoirs and transferring much of the pain to the Lower Basin.
For the time being, "We’re safe," says Randy Seaholm, chief of the water-supply section of the Colorado Water Conservation Board.
That doesn’t mean that Seaholm and every other water manager in the Colorado River Basin isn’t taking the issue seriously. And no wonder: Lake Powell is half empty. Lake Mead is in only slightly better shape.
A few decades from now, we may look back on our present situation and realize that Big Daddy Drought already had its hands around our throats; we just didn’t know it.