The waters of the Rio Grande are closely regulated. But what about the water hidden in aquifers deep below the Mexico-Texas border?
A sudden bridge collapse in Italy has sparked interest in the safety of structures worldwide.
Bear sightings at Yosemite National Park are down, but the park's infamous traffic poses a new threat.
States across the country are holding public hearings on what to do about contamination with a class of persistent chemicals known as PFAS.
Ten percent of the world’s oceans are on track to be protected by 2020. But do they need to be?