Brady Smith, U.S. Forest Service, Southwestern Region, Coconino National Forest

Current climate change models assume that trees recover swiftly after a drought ends. That’s not true, according to a new study.

Researchers examined tree-ring data from more than 1,300 sites around the world. By comparing the rings to rainfall records, they could track tree growth before, during, and after droughts.

They found most trees grow slower than normal for 1 to 4 years following a drought.

It’s called a “legacy effect,” and it hasn’t been included in climate change models.  

Lake Mead National Recreation Area

Prolonged drought in the Southwest has caused a rapid drop in the water level of Lake Mead. That’s putting water supplies to some major cities in jeopardy. But it’s also exposed some of the area’s history and a long-submerged town. Arizona Public Radio’s Ryan Heinsius reports. 

Farmers in central Arizona are working together to protect a precious resource that flows through their land. The Verde River supplies every drop of water they use for irrigation, and everything else in their lives. As the drought swallows up lakes and rivers across the West, Verde Valley farmers are embracing new and old technology to ensure their water supply doesn’t dry up. Arizona Public Radio’s Aaron Granillo reports.

Melissa Sevigny

The City of Williams west of Flagstaff is in the process of drilling a new well. Like many places in the Southwest, it’s facing drought and rising demand. But there’s another reason water supply is a challenge in Williams.  A fluke of geology has forced the city to take the lead in the hunt for groundwater on the Colorado Plateau.    

Federal water managers are due to release a monthly projection of water levels at Lake Mead on Monday, and the rain in May might change what they say.

Last month, the U.S. Bureau of Reclamation reported that the Colorado River reservoir behind Hoover Dam could reach a low point in January 2017 that would force supply cuts to Arizona and Nevada.

Officials heading water agencies in the two states and California took a wait-and-see approach, and pointed to fluctuations in regional precipitation since January.

National Park Service, Lake Mead National Recreation Area

Federal water managers are projecting Lake Mead will drop to levels in January 2017 that could force supply cuts to Arizona and Nevada.

Arizona's water allocation could be cut 11.4 percent and Nevada's by about 4.3 percent.

A closely watched U.S. Bureau of Reclamation report released Monday predicts water levels will be just 2 feet above a trigger point next January on the Colorado River reservoir supplying much of the Southwest's drinking water.

The so-called interim guidelines chart a decline leading to a declaration of a shortage the following year.

Measures of Drought

Dec 4, 2013
University of Arizona Climate Assessment of the Southwest

Drought is a universally understood phenomenon — especially here in the arid Southwest. But what does drought really mean? To help define the term, and the concept, scientists use several commonly used drought indices. Each summarizes thousands of data points on rainfall and other information into a single handy number.

Arizona Game and Fish

Across the Southwest more and more bears have shown up in people’s kitchens, garages and flower beds. Wildlife officials in Colorado say in that state alone they had to euthanize 133 “problem bears” last year. And in Arizona at least a dozen bears have been euthanized, and scores of sightings have many people rattled.

Despite this year’s abundant monsoon season, researchers say climate change could be pushing the Southwest into a period of sustained drought. 

Adrian Florido

Imperial County, east of San Diego, has one of the worst childhood asthma problems in California.