Independence is an admirable trait in an elected official. But that independence should never betray an elected official's constituency.

It's one thing to vote one's conscience, but it's entirely another to categorically reject the needs and interests of the people who put the official in power.

That's exactly what new Clark County Commissioner Chris Giunchigliani did Thursday when, as a member of the Southern Nevada Water Authority Board of Directors, she cast the lone vote against spending $43.5 million for more than 13,000 acres of ranchland in White Pine County, about 250 miles north of the Las Vegas Valley.

Over the past eight months, the water authority has spent $79 million to acquire property in the Spring Valley, from which it plans to run a $2 billion pipeline to Las Vegas. The proposed pipeline is a badly needed insurance policy for urban Clark County's future water needs. Importing billions of gallons of groundwater from rural Nevada would allow the Las Vegas Valley to continue growing, even if the drought along the Colorado River worsens.

Pat Mulroy, general manager of the water authority, has said the pipeline needs to be in operation by 2015 to forestall drastic conservation measures.

The thought of the Las Vegas Valley going thirsty is frightening. Tens of thousands of jobs would be lost if the County Commission and city councils had to put the brakes on residential and business construction. Draconian restrictions on water use, going well beyond common-sense conservation, would tarnish residents' quality of life. The very future of the metropolitan area would be in jeopardy.

But none of that matters to Commissioner Giunchigliani, apparently. She thought the money might be better spent on conservation programs.

Ms. Giunchigliani's vote might have been justifiable if she were still a member of the Nevada Legislature, where every vote affects the entire state. But she vacated her seat in the Assembly to serve on the County Commission. And the greatest long-term concern for county government, residents and businesses is the area's near complete dependence on the Colorado River. If the area is going to prosper into the 21st century, it must have additional sources of potable water.

If Ms. Giunchigliani can't understand this, and understand why it's important for the water authority to acquire land in White Pine County to keep the pipeline project moving forward, she shouldn't serve on the authority's board of directors. Just as commissioners voted in 2005 to remove Tom Collins from the Metropolitan Police Department's Fiscal Affairs Committee when he defied his colleagues and county administration in support of organized labor and obscene pay raises for police officers, so should they bounce Ms. Giunchigliani from the water authority board.