Beware of anyone who says you have to sign now or the deal is off.

That's a good suggestion for sales pitches. It ought to be a requirement for bills in Congress (health-care reform anyone?). It should be an iron-clad rule when it comes to water rights in the arid West.

Because, as some members of the Millard County Commission put it to the Deseret News editorial board last week, "If the desert collapses, how do you bring it back?"

Millard County is ground zero for a percolating water dispute between Utah and Nevada — one that most likely will end up in court, soaking (pardon the pun) taxpayers before it is resolved. But that wouldn't be the worst outcome. A little delay through the legal system might not be such a bad thing in this case.

At the heart of this dispute is Las Vegas' insatiable thirst for growth. That city, built on a landscape I thought resembled the moon when I moved there for a short time 26 years ago, keeps spreading subdivisions like sagebrush.

The Wasatch Front is doing the same thing, of course. But in Las Vegas, where nature provides only 4.5 inches of rain a year, those subdivisions can't sustain themselves much longer unless they are watered from somewhere else.

So the Southern Nevada Water Authority wants to suck billions of gallons from beneath Utah's portion of the Snake Valley. For years, Utah and Nevada have been negotiating this, and now a proposed compromise has been made public, and hearings are being held, and a signature is needed within two months.

And the people of Utah's arid valleys couldn't be angrier.

I should note up front that the agreement wouldn't authorize anyone to pump anything. As officials have emphasized, it provides a framework for future decisions and leaves time for more scientific study.

But frameworks are important, especially if they require one side to agree in principle to give something up. In this case, Snake Valley water would be split 50-50 between the states, under the assumption that much of the water beneath Utah comes from rain that falls on Nevada mountains. But the Utahns in Millard and Juab counties have figures that show the water, both historically and through natural discharge, belongs to Utah at a ratio of 78 percent to 22 percent.

Figures and maps can make the eyes glaze. There are some other, more dramatic reasons you should be concerned about all this. Water beneath the Snake Valley isn't easily replenished. Some scientists believe it keeps in place contaminated water surrounding the Great Salt Lake to the north. If Nevada removes much of the good water, the bad may take its place, killing vegetation above.

And if that happens, the winds that regularly whip those desert valleys could create giant dust clouds that turn the blue skies over the Wasatch Front brown.

That's all speculation, of course. No one actually has ventured below the ground to see what's there. But can Utah really take a bet from Las Vegas that Snake Valley water isn't important to the state's ecosystem?

The agreement would set aside money for fixing any problems that result. But that doesn't make anyone feel better. The Millard County folks doubt seriously that once water is being pumped to new homes in Las Vegas, anyone will have the authority to turn it off.

Utah Attorney General Mark Shurtleff won't take sides on the agreement, but he said, "There are certain things we won't give up." He also believes the issue will end up in court, although he's trying to avoid that.

There may be another angle. Various sources tell me they think Nevada Sen. Harry Reid is behind the scenes, threatening to withdraw support for a Lake Powell pipeline into St. George unless Las Vegas gets to pump the Snake Valley.

That's why a delay by legal challenges might not be so bad. By all accounts, next year's election may bring a flood of change to Nevada's political landscape.

Jay Evensen is editor of the Deseret News editorial page. E-mail: even@desnews.com. Visit his blog at deseretnews.com/blogs.