Melissa Sevigny

Negotiations over the water supply for 40 million people are hinged on how you interpret the words "will not cause," written into the century-old Colorado River Compact.

A particular kind of soil bacteria could help farmers produce food during droughts, according to Arizona ecologists.

Some doctors are operating on hands in a new way: with the patient wide awake. It eliminates the risks and side effects of general anesthesia.

Snowflake is a small town in eastern Arizona. It’s got more deer and elk than people, and that can make it dangerous to navigate rural roads at night. That’s why students at Snowflake Junior High invented a system of flashing lights to warn drivers when a big animal is nearby.

The Navajo Nation is arid and vast — nearly 30,000 square miles. Hydrologists struggle to collect much-needed measurements of rainfall there. But now they have help from NASA satellites.

Astronomers voted on the definition of a planet in 2006 and Pluto didn’t make the cut. Now some scientists are suggesting a simpler and much more inclusive definition.

The public can now join the hunt for the elusive Planet Nine, a massive planet astronomers believe might be hidden beyond Neptune.

In six months, a total solar eclipse will cross the United States from coast to coast. The last time that happened was nearly a century ago.

Researchers say Americans are willing to pay more on their taxes to restore springs in Grand Canyon National Park — even when they’ve never visited the famous landmark.

NASA is keeping track of dust that settles on snow in the Rocky Mountains. The research will help hydrologists improve their predictions for how fast the Colorado River will rise this spring.