In March 2019, storm clouds rolled across Oklahoma; rain swept down the gutters of New York; hail pummeled northern Florida; floodwaters forced evacuations in Missouri; and a blizzard brought travel to a stop in South Dakota. Across much of America, it can be easy to assume that we have more than enough water. But that same a month, as storms battered the country, a government-backed report issued a stark warning: America is running out of water.
Within as little as 50 years, many regions of the United States could see their freshwater supply reduced by as much as a third, warn scientists. Of all the freshwater basins that channel rain and snow into the rivers from which we draw the water we rely on for everything from drinking and cooking to washing and cleaning, nearly half may be unable to meet consumers’ monthly demands by 2071. This will mean serious water shortages for Americans.
Shortages won’t affect only the regions we’d expect to be dry: with as many as 96 out of 204 basins in trouble, water shortages would impact most of the U.S., including the central and southern Great Plains, the Southwest, and central Rocky Mountain states, as well as parts of California, the South, and the Midwest. And if 50 years seems like a long way off, the reality is much sooner: shortages could occur in 83 basins as early as 2021. With 40 out of 50 states expecting water shortages, it’s time to start thinking about where our water is going.
From the snow-capped Rockies to the flat expanses of the prairies, and from the wetlands of Florida to the deserts of Arizona, the U.S. is a country of geographical extremes with rainfall patterns to match: Louisiana gets over 60 inches of rainfall a year, while in Nevada, less than 10 inches of rain falls annually in valleys and deserts. But climate change is impacting precipitation. In broad terms, while the wettest regions of the U.S. are getting wetter, the drier areas are getting drier, and there are some seasonal shifts in water patterns—rising temperatures mean the snowmelt that feeds many rivers begins and ends earlier, contributing to summer water shortages. Even where precipitation is projected to increase, mostly in the nation’s northern regions, the trend is toward more intense concentrations of rainfall that are difficult to capture and use. At the same time, 145 basins are expected to be drier, especially in the Southwest, southern Great Plains, and Florida. In the West, California has already faced some of its worst droughts in recorded history.
Along with decreasing rainfall comes rising temperatures. By 2050 the U.S. could be as much as 5.7°F warmer, and extreme weather events, such as heatwaves and drought, could be more intense and occur more frequently. As temperatures warm, evaporation increases, further decreasing water in lakes, reservoirs, and rivers. For example, every degree of warming in the Salt Lake City region could drop the annual water flow of surrounding streams by as much as 6.5 percent—for cities in the western U.S. that rely on cool temperatures to generate snow and rain, warmer weather is bad news. [ … ]