After years of living through the seemingly never-ending nightmare of a record-setting drought, residents of the American West awoke in 2018 and 2019 to something very different.
Take California’s capital city, Sacramento, for instance. The month of May usually averages less than an inch of rainfall. But in 2019, May brought 3.42 inches of rain. That’s more than half of what Sacramento saw in the entire year of 2013.
So turn on those spigots and jump for joy. Happy days are here again. Right?
Sort of. Kind of. Er… not really.
Most people already know that recent years have brought historically erratic weather patterns. Hotter hots. Bigger storms. Crazy stuff.
This is partially attributable to climate teleconnections — a phenomenon first recognized by a British statistician named Gilbert “Boomerang” Walker in the late 1800s and early 1900s. Walker — who got his nickname because he was fascinated by the mathematical properties of throw-it-and-it-comes-right-back weapons used by Australian aboriginal hunters — was also interested in the physics of weather, and particularly monsoons in India. Using vast troves of data he and others collected from around the world, he identified a seesaw pattern that connected changes in atmospheric pressure in the Indian and Pacific oceans, and correlating temperature and rainfall patterns across the global tropics. These days, most folks know this teleconnection as the El Niño Southern Oscillation.
Teleconnections are… well... sort of wobbly, and in recent years they’ve gotten really wobbly. The result, in the American West, has been some years that are really wet and some that are really dry as the result of processes that none of us can control on a personal level.
So what does that mean for us individually? Well, it means that we need to be attentive to water conservation — as much when rainfall and snow packs are high as in the years in which there is very little precipitation. That’s because, more than ever before in human history, we’re reliant on reservoirs — large natural or artificial lakes, often built upstream of a dam, that are used to collect and store water.
Sure, some of the water that falls from the sky in years of high precipitation is going to be used right away. But a lot of it is going to be kept behind one of the more than 91,000 dams in the United States for coming years, and even coming decades.
Even in long periods of drought, reservoirs take many years to drain. But with more frequent droughts that last longer — and rapidly growing populations across the American West — we can’t be certain that there will always be at least some water at the bottom of the reservoir when the next deluge comes.
Likewise, even in years with lots of precipitation, these bodies of water can take many years to fill, but greater uncertainty about future use can cause water managers to want to hold onto more water than might be prudent. The best example of this issue is Lake Oroville, which saw so much water input after a record drought that, in 2017, dam engineers couldn’t spill the water fast enough and had to use an emergency spillway, prompting the evacuation of nearly 200,000 people downstream.
So, it’s pretty clear where this is going, right? Predictable reservoirs are happy reservoirs no matter how much water is falling from the sky in the present year. And happy reservoirs mean happy people, since nobody enjoys the sorts of emergency water restrictions that were very common across Western states in the mid-2010s.
Those rules — affecting homeowners, farms and businesses, the maintenance of cemeteries and golf courses, the operation of car washes and water parks, and even the price of a gallon of water — aren’t gone forever. What you do every year to conserve water will help keep reservoir levels up in times of drought, reducing the scale and severity of water-use restrictions. Moreover, developing water-smart habits is easier during years when no restrictions are in place — making it easier to adjust when restrictions do occur.
So, sure, when high precipitation years come there’s plenty of reason to celebrate. But it’s also time to keep on saving — for a not-so-rainy day.
Jonathan Meyer is a climatologist with the Utah Climate Center at Utah State University, where Matthew D. LaPlante is an associate professor of journalism.