Nearly a century ago, the people who built Hoover Dam on the Colorado River were “inspired by a vision of lonely lands made fruitful,” as the inscription at the base of the flagpole on the Nevada side puts it. They could not know they were living in what would prove to be the wettest century of the past millennium in the American West.

We sure know that now. The “megadrought” that began right at the turn of the 21st century is still going on, and this year is shaping up to be a bad one, in part due to climate change,Alejandra Borundawrites for Nat Geo.

Most of Californiawas declared under drought emergency Monday, mainly because the snowpack that Californians depend on to help tide them through summer is…