Drilling contractors work amid the scrub of the Hiawatha National Forest in Michigan’s Upper Peninsula in this 2015 photo. They were installing monitoring wells near the closed Raco Army Airfield site as part of ongoing remediation investigations. Source: U.S. Army Corps of Engineers

A U.S. Geological Survey team performs coring for a geo-chemistry study at Little Sheep Creek near Lima, Montana, in this 2019 photo. Source: Preston Keres / USDA