This is an archived article that was published on in 2015, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

Logan • Drought is nothing new to Westerners.

But this one is different. It hasn't been this dry in the West since the early Middle Ages.

"The current drought is the driest in 1,200 years for a three-year period," University of California-Berkeley professor Lynn Ingram told an audience Wednesday at Utah State University's 2015 Spring Runoff Conference.

Growing evidence suggests historic and lengthy "megadroughts" — lasting for at least 20 years — wreaked havoc on the Western United States and may have caused some inhabitants to flee the region, said Ingram, a professor of Earth and planetary science.

"We are looking beyond the historic and prehistoric record," she said. "We are extending back in time to the paleoclimate record."

Ingram, co-author of the book "The West Without Water: What Past Floods, Droughts and Other Climatic Clues Tell Us About Tomorrow," said "indirect evidence" of past droughts and floods has been studied in tree rings, wildfire frequency and sediment from lakes, oceans and marshes.

The last megadrought occurred from 1560 to 1580. The last year of that drought, 1580, was the driest year in the past 1,000 years.

Back 15,000 years ago, when the 30,000-square-mile Lake Bonneville covered much of what is now Utah, the climate was cooler and wetter, Ingram said.

But that changed about 10,000 years ago, when a general warming trend started. The average temperature has increased since that time with several key warming periods — including one 6,000 years ago and another during the Middle Ages.

Ingram said there were at least two megadroughts between A.D. 900 and 1350.

Those dates correspond with the disappearance from the Four Corners area of the people commonly known as the Anasazi. Some believe extreme drought forced the people to flee the canyon country of the area.

Ingram said there is evidence other groups of people living in the West at that time also abandoned hostile environments.

On the flip side of the historic trends, she said, severe flooding also is a possibility with extreme precipitation.

Megafloods occur on average every 200 years. The last massive flood was in 1861-62.

Both megadroughts and megafloods will be possible in the western United States, Ingram warned.

"Storms are expected to be larger and more frequent," she said. "We have to plan for both water scarcity and more flooding. We need to learn how to harness that water."

Ingram suggested Westerners need to plan for a warmer and drier future.

Other fallout from changing weather includes more frequent wildfires, agricultural collapse and increased water conflict between regions.

Ingram told the Logan audience 70 percent of the western U.S. — including about 52 million people — is currently in a drought. Some locations in California and Nevada are in extreme or exceptional drought. And with snowpack at a historic low of 6 percent of normal, things look no better for the rest of 2015.

On Wednesday, California Gov. Jerry Brown ordered officials to impose mandatory water restrictions for the first time in that state's history. The California Water Board must find ways to cut usage by 25 percent.

California will require campuses, golf courses, cemeteries and other large landscapes to significantly cut water use. Local governments will have to replace 50 million square feet of lawns throughout the state with drought-tolerant landscaping. And the state will create a temporary rebate program for consumers who replace old water-sucking appliances with more efficient ones.

Utah Gov. Gary Herbert has hinted at possible water rationing in Utah as the scope of the current drought becomes more clear.

The Associated Press contributed to this story. Twitter: @BrettPrettyman —

Ways to conserve water:

• Replace lawns with drought-tolerant plants.

• Recycle and reuse water.

• Increase water efficiency in agriculture.

• Replace appliances with water-efficient models.

• Recharge groundwater with recycled wastewater.

• Price water to reflect scarcity and environmental costs.

• Reduce your water footprint. (Consider the amount of water it takes to produce food and other products like clothing.)