Tom Ross: No guarantees Lake Powell will fill

Tree rings suggest Western droughts can last for 20 years or more

Advertisement

Among the many weaknesses displayed by humans is an inability to think in timeframes much beyond the boundaries of our lives. Personally, I often cannot think beyond what's for dinner tonight.

This tendency toward egocentricity often shapes our responses to natural environments and ecosystems.

I was reminded of this phenomenon during the great wildfires that burned through Yellowstone National Park in 1988. It came up again in late October 1997 after a winter storm leveled thousands of acres of trees during the Routt Divide Blowdown. More recently, human shortsightedness popped up at the Yampa River Basin Water Forum at Hayden High School on Thursday.

In the case of the Yellowstone fires, many people decried the decision to let the fires burn through mature stands of lodgepole pines because it would leave America's first national park blackened for decades to come.

It took education to help people understand that in terms of the lifetime of a North American conifer forest, the life of a human being is the blink of an eye.

The same applies to any remorse we feel about the blowdown and the resulting beetle infestation that could claim thousands more acres of trees.

If the beetle infestation manifests itself the way scientists think it will, the forest will never be the same during our lifetimes. Oh well. The forest eventually will heal itself.

It was Eric Kuhn of the Colorado River Water Conservation District who helped about 60 people at the water forum last week understand that we cannot really appreciate climate cycles in the semi-arid American West because they span centuries.

Kuhn found a dramatic way to relate that point to the future of Lake Powell and the Yampa River.

Climatologists have done a study of ancient tree rings, Kuhn said, that indicates the Colorado Plateau, including Arizona, Utah, Colorado and portions of Nevada, endured a drought of epic proportions spanning the turn of the 16th century into the 17th century. Scientists can make assumptions about historic precipitation levels from the growth rates revealed by the space between annual tree rings.

The drought that persisted from 1579 to 1616 would make our current drought pale by comparison.

Kuhn asked his audience to make a significant leap of faith.

Pretend, for purposes of discussion, that Glen Canyon Dam on the Colorado River in extreme southern Utah was in existence in 1578. Not only that, it was brimful. The drought that began to take hold the next year slowly drained Lake Powell until 11 years later, the reservoir was empty.

The data collected from the tree ring study suggests the drought was so severe, the reservoir would have remained empty for eight consecutive years. Now imagine the consequences for major metropolitan areas from Denver to Los Angeles.

Without storage in Lake Powell, Colorado and Denver would not have been able to fulfill their obligations to states in the lower Colorado Basin. However, Las Vegas and Los Angeles surely would have withered once Denver was sucked dry.

Lucky for us, Los Angeles didn't exist in 1578.

Fast forward to the present, and Kuhn says that if current drought conditions persist, Lake Powell will fall to one-third of its capacity by next summer. The implications are readily apparent.

States in the Upper Colorado Basin including Colorado, Wyoming and Utah are obligated to allow more than half the water in the Colorado River to flow to the lower basin states of Arizona, Nevada and California with a small portion reserved by treaty for Mexico.

The division of water is governed by the Colorado River Compact, which was signed Nov. 24, 1922, in Santa Fe, N.M. However, the compact is flawed, Kuhn said. To begin with, it assumed the Colorado carries more water than it actually does. Other ambiguities in the compact raise concerns about whether upper basin states always will be able to meet their obligation.

Moffat County irrigator Darryl Steele has been studying Northwest Colorado's water needs through 2045 as a member of the Statewide Water Supply Initiative. Steele says he's fearful about the future of the Yampa River.

"One of the things that really has me worried is that the Gunnison and Colorado (rivers) will develop and appropriate all of their water before we do," Steele said. "This is the state's water, and I'm afraid that some day, the state's going to look around and ask, 'Where are we going to get the water for our downstream appropriations?'"

Steele's theory is that the state of Colorado's best alternative will be to send unappropriated water from the Yampa (and probably the White River) to Arizona, Nevada and California.

"I think we need to be very diligent in making sure the state does not do that," Steele said. Instead, he thinks the major river basins should shoulder a proportionate share of any unmet obligations to the lower basin.

Kuhn says Steele is asking the right question. But the answer may not be revealed until the conclusion of several decades of legal battles.

In the meantime, we expect that everything will turn out just fine in our lifetimes, and we'll have all the water we need because this drought will turn around soon. Or will it?

Tree ring history teaches us the answer is, "perhaps not."

Now, all that remains to be answered is, "What's for dinner?"

Comments

Use the comment form below to begin a discussion about this content.

Requires free registration

Posting comments requires a free account and verification.