Happily, the U.S. Bureau of Reclamation is making good on its vow to focus on "new ways to supply water and power to Western states."

The bureau announced recently that it would act "as a facilitator for water-marketing proposals." That is another welcome sign that it is essentially out of the dam-building business.That change, of course, is less a bold policy departure than an inevitable response to economic and political reality: There simply aren't many places in the West anymore where big new water projects make sense enviromentally and financially.

Hence, the increased interest in water-marketing arrangements, in which farmers or others with water rights sell them to industries or cities. A number of Western communities have bought or leased water rights in recent years.

But until now the bureau had slowed the trend by making it difficult for farmers to sell water from federal storage projects, which were devoted to agriculture. Presumably the policy shift will lower some obstacles to marketing.

Despite its efficiency as a means of allocating a scarce resource, water marketing isn't without critics. They note that the sale of agricultural water to urban areas can dry up vast areas of farmland.

While that's true, marketing agreements can be fashioned to prevent such an outcome.

On the other hand, if there are farmers who want to take the money and quit business, why should they be prevented from doing so? Water-rights agreements, after all, are market transactions. Farmers aren't forced to sign at pitchfork-point.

Some conservationists worry about soil erosion and the effects on wildlife from large-scale water marketing. Their concerns, too, can be met through well-crafted agreements - and government watchfulness. Moreover, marketing can promote water conservation when farmers are allowed to sell what they save.

And in many cases the only possible alternative for Western water development is the financially impractical strategy of dam construction, hardly an evironmentalist prescription.