There is a large white bathtub ring lining the shores of Lake Powell, one of the West's most crucial reservoirs.

The reason: the Arizona lake is at its lowest level since it was filled three decades ago with the construction of the still controversial Glen Canyon Dam.

How low? The lake's level is down 87 feet from its peak. The last time it was this low was in 1973, when the reservoir was still filling with Colorado River water after the dam went up 10 years earlier.

Managers with the U.S. Bureau of Reclamation say levels will likely drop another 5 feet before the spring runoff from winter snows begins to pour into the artificial lake.

Demand outstrips supply of the West's most precious resource, with California, Arizona and Nevada suffering from drought and struggling to get their minimum deliveries from Lake Powell. There still might be 4 trillion gallons left, but that only equals a two-year supply of water for the three states.

Meanwhile, parched Colorado is releasing the minimum required into the Colorado River because of its own dry conditions.

The falling water level has forced marinas and the National Park Service to extend boat ramps hundreds of feet from shore.

On the up side: ancient canyons inundated by the erection of Glen Canyon Dam are exposed to air and light again. And there is plenty of new beachfront.

-- William Booth

Jared McKeeth of Harrisville, Utah, makes a jump on a wakeboard in Lake Powell. The lake's receding waters have created a scar on the red rock walls.