That amounts to about two-thirds of the water the Southern Nevada Water Authority had requested permission to pump. Authority General Manager Pat Mulroy described her response Monday as "a huge sense of relief. ... What this says to me is that this (pipeline) project is now a project."

Opponents of the project -- who have tried to compare it to the "water grab" in which Los Angeles captured much of the water resources of the rural Owens Valley 80 years ago -- appeared pleased that the state engineer OK'd only a staged development of the water, and pointed out the lower authorized flows could make it harder to economically justify the $2 billion pipeline project.

"I would like to see how they're going to pencil this one," commented Bob Fulkerson, executive director of the Progressive Leadership Alliance of Nevada, who called the ruling "a victory of sorts for our side."

"I guess you've got more money than you know what to do with if you don't care about the per acre-foot cost," he added.

The federal Bureau of Land Management must also sign off on the environmental impact of the project -- a review process that could take two more years.

But Ms. Mulroy says the decision leaves the authority on schedule to start delivering water to Las Vegas from Lincoln, White Pine and rural Clark counties in 2015, by which time the authority could own much of the private land in the Spring Valley, east of Ely, which is now planned to be the northern terminus of the pipeline.

In separate transactions since July, the authority has purchased seven ranches in that million-acre watershed for a combined price of almost $79 million.

The state engineer is indeed wise to plot a cautious course, in which gradually increasing water withdrawals will be monitored to guarantee no calamitous environmental impacts in the north.

But there's no mistaking the fact that this ruling -- consistent with state law that brands water a state resource, to be allocated in the best interest of the state as a whole -- is a huge victory for the continued growth of Las Vegas, which could otherwise face crippling restrictions on new construction, should drought continue to limit water flows in the Colorado River.

Critics are right -- that water grows more expensive if fixed pipeline costs have to be amortized across fewer acre-feet. But once the pipeline is in place, political realities will make it difficult to deny Las Vegas -- the state's economic engine -- as much water as can be reasonably transported.

In the long run, this is not the ultimate solution. The preferable "fix" will require a revisiting of the law of the river, allowing free-market water pricing in which California melon farmers and tax-subsidized Arizona cotton growers can be expected to willingly sell water rights to higher-bidding urban areas -- win-win, consensual transactions now forbidden by federal law.

Until that day comes, the water authority's plan to diversify Southern Nevada's water resources with the White Pine pipeline is a reasonable economic safeguard.

Fortunately, the state engineer appears to agree.