That's not to say the dry weather pattern will continue that long. "The drought of the '50s was followed by two decades of somewhat below-average inflows," he said. "But it's also worth noting it's not uncommon to see a wet year in the middle of a multiyear drought."

In fact, one wet year and one average year were recorded during the otherwise dry 1950s.

"In spite of five years of drought, there still is a total of 31.8 million acre-feet of water storage in the Colorado River system, over seven states," he said.

Much of the value of Lake Powell to the Upper Colorado River Basin states — Utah, Arizona, Colorado, New Mexico and Wyoming — is not in their direct use of Lake Powell water. Even though the lake is almost entirely in Utah, the storage is not used here.

Instead, the dam generates electricity, and the reservoir allows Upper Basin states to fulfil their legal requirement to the Lower Basin, the states of California, Nevada and Arizona. Lower Basin water is stored in Lake Mead for distribution.

Under a 1928 compact, the Lower Basin states are entitled to a certain proportion of Colorado River system water. If Lake Powell were not present to store it, in a severe drought, Colorado River water could be running past thirsty Utah farms destined for California agriculture, and Utahns would be unable to use it.

But because lakes Powell and Mead store Lower Basin water, Utahns still can capture water sources.

"For the sake of the whole basin, it's critical that they (Mead and Powell) operate in harmony," Wirth said.

Not only is the region in an exceptional drought, he added, "but we have more demand on the system than we've ever had before."

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