It develops in stages, a story that builds upon itself. A few cloudless days. Then a rain-free week. Soon a hot, dry month.
Now the hills are brown and the crops need watering — the first signs of drought.
The intensely dry conditions that have settled over the American West and Upper Midwest this year are well past the brown hills stage. Nearly 89 percent of nine western states are in some form of drought, and more than a quarter of the region is considered in exceptional drought, the worst category in the U.S. Drought Monitor.
The indicators of widespread dryness are everywhere. Lakes Mead and Powell, the major reservoirs on the Colorado River, are 35 percent full with a two-year outlook that worsened each month this spring. California officials told vineyards along the Russian River in May that the system is too depleted for irrigation. In Utah’s Great Salt Lake in April, sailboats were lifted out of receding waters too shallow to float. In the Klamath River that flows between Oregon and California, few juvenile salmon are expected to survive this season. In Arizona, the Rafael Fire, burning in the Prescott National Forest some 25 miles southwest of Flagstaff, grew to 36,000 acres since it was sparked on June 18 by lightning.
When water stops flowing, painful days are at hand — even if the pain is not immediately evident.
“The complexity of the drought phenomenon is not well understood by most people,” said Roger Pulwarty. Some people will say that we’ve experienced drought before, he mused. “Well, not like these. Not for this extent, not really addressing all the diverse ways in which it affects our economy, through the environment, through trade.”
Pulwarty has wrestled with these questions about the consequences of drought longer than most. He was the director of the National Integrated Drought Information System, a drought monitoring and planning collaborative set up by Congress. And he was the coordinating lead author for a United Nations special report on drought that was published earlier this month.
Drought, like a hurricane, tornado, or earthquake, is a potentially dangerous natural hazard. But Pulwarty notes that droughts have distinctive characteristics that separate them from other calamities. They are geographically diverse, spreading across a few counties or entire watersheds and regions. They are slow to begin but can last indefinitely, some “megadroughts” upending social and political stability over several decades.
Drought, like a fearsome boxer, has a long reach. And like that fearsome boxer, the long reach of drought is pummeling.
Consider this chain of events. Drought increases the risk of fire. It dries out vegetation and kills trees, turning forests into matchsticks. Fires in river headwaters don’t just burn trees. They also send ash and debris into reservoirs and rivers. The Las Conchas fire in northern New Mexico in June 2011 pumped so much ash into the Rio Grande that the Albuquerque Bernalillo County Water Utility Authority had to close its drinking water intake on the river. When they rampage through developed areas, fires can contaminate plumbing systems and water distribution pipes with volatile organic chemicals. The smoke is a public health threat.