Fresh Ideas: Drought packs a heavy punch for the West

On March 13, the U.S. Drought Monitor said Carson City was in extreme drought, along with much of northwestern Nevada.

So I’ve been reading about drought in the American West, and I discovered the answer to some longtime mysteries. First, there are the tree stumps sticking out of the water in Tenaya Lake in Yosemite. The stumps sit about 50 yards off the beach in water so deep you can’t see the bottom. How did they get there?

The other mystery is the ancient adobe granaries perched on canyon walls in southern Utah. It was impossible not to notice that the people who built their granaries way up the canyon walls must have been afraid of something.

Since my youth spent wandering around the wilderness of the American west, the science of paleoclimatology has developed and those mysteries now have answers.

The trees now submerged by 70 feet of water grew there when Tenaya Lake dried up, probably about 800 years ago, in a period known as the medieval drought. The medieval drought lasted 500 years.

And the granaries? That same severe drought destroyed the civilization of the Ancestral Puebloan people of the southwest canyons. As the climate dried, desperate people hoarded their remaining food in spots as inaccessible as possible.

Paleoclimatology tells us that the climate of the West is one of regular drought and floods. The 150 years since European American settlement have been relatively benign climate-wise, but there is no assurance that will continue. And when mega-droughts do come again, it will be to a region where millions now live.

It is clear that we need to be planning for drought and conserving. Curious about how Carson City is doing in the current drought, I talked to Curtis Horton, chief of operations for Carson City’s water system, and David Bruketta, city utility manager.

They told me about 95 percent of our water is from municipal wells and 5 percent is surface water.

How are those water supplies affected by the current drought? Curtis said right now we’re in good shape, though if the drought lasts another five years we could be hurting. The immediate effect of the drought is that we will lose our surface water earlier and will rely more on municipal wells. But the city has just completed a Regional Intertie project bringing in water from the Minden area. Components of the Intertie are operational, but it will be a few years before it is complete. This water will help us out in current and future droughts.

I asked if the city has done any long-range planning regarding maintaining adequate water supplies during multi-year droughts. The Intertie, David said, is part of that planning, and our water system, with the addition of the Intertie, should support population growth to about 70,000.

Compare this to the predicament of Las Vegas, where the water district is constructing a “third straw” in Lake Mead — a third domestic water intake, at a cost of $800 million, for when the water level falls below the first two.

And still, some climate scientists estimate that with predicted reduction of runoff in the Colorado River Basin, “there’s a 50% chance that both Lake Mead and Lake Powell could reach ‘dead pool,’ rendering them useless for hydroelectric power generation or useful water storage by as early as 2021.”

In Carson City we’re much better off than that — for now.

Anne Macquarie blogs about clean energy and climate change in Nevada at nevadanscleanenergy.org.