The New York Times is reporting that the water level in Lake Mead has hit the lowest point since the reservoir was first filled, following the construction of Hoover Dam 75 years ago. If you’re looking for a symbolic date that signals the new realities of water in the American West, mark today on your calendar. 

There are far-reaching implications if the dry conditions seen over the past decade continue, current levels of demand continue, and the lake level keeps falling. A decline of eight more feet — to 1075 feet above sea level — would trigger water shortages. If the lake falls an additional 25 feet, to 1050 feet, it will idle Hoover Dam’s massive turbines. At that point, the intakes for the generators start drawing in air, instead of water. 

When the dam was built, these events weren’t even considered a possibility. But today, the U.S. Climate Change Science Program predicts that the Colorado River system could be 10-25 percent drier in the future than it has been historically. As a result, researchers are now debating how long it might take for Lake Mead to run out of water.

Three quarters of a century ago, the Colorado River was a nearly untouched river system. Remember, Hoover Dam was built just 70 years after John Wesley Powell first ran the wild rapids of the Grand Canyon. The dam represented new technology to tame the American frontier, providing abundant power and water. Today, however, signals the end of the hydraulic frontier. Welcome to the age of water efficiency.

So what do we need to do differently to meet our needs in the future? Here’s NRDC’s 2007 report, In Hot Water, with our suggestions.

This article was reprinted with permission from Switchboard.nrdc.org.