In the spring, melting snowpack in the Rocky Mountains feeds the Colorado River, which supplies drinking water to 40 million people across seven states. But as the climate warms, snowpack is shrinking, prompting concerns over water shortages.

One technique that can help increase precipitation is called cloud seeding. It’s been used in some areas since the 1950s.

A machine or airplane releases particles, such as silver iodide, into developing storm clouds. The particles attract molecules of water vapor, and if the conditions are right, those droplets form more rain or snow.

Mohammed Mahmoud is with the Central Arizona Water Conservation District, which has funded cloud seeding projects in the Rocky Mountains for years.

“The type of cloud seeding we’re interested in is winter cloud seeding, and what that does is enhance the snow pack,” he says. “So that ultimately, in the spring, that enhanced snowpack can increase the runoff that water users rely on downstream.”

The practice remains controversial, but researchers have found that cloud seeding can increase the amount of precipitation that falls in a storm by up to 15%.

So it can help reduce the impact of climate change on critical water supplies.

Reporting credit: Sarah Kennedy/ChavoBart Digital Media.