‘Although the tap-water ban was lifted in the wake of West Virginia\’s Elk River chemical leak, the long-term ecological impacts of the spill remain uncertain.

On Monday, the 300,000 residents of nine counties in West Virginia were told that they could resume drinking and using their tap water, five days after an estimated 5,000 gallons of the chemical 4-methylcyclohexane methanol (MCMH) leaked into the Elk River near Charleston.

As National Geographic previously reported, MCMH is used as a foaming agent to wash certain types of coal before it is sent to market. The chemical leaked from a 48,000-gallon storage tank owned by Freedom Industries, located about a mile upriver from a drinking water treatment plant operated by West Virginia American Water, affecting the central and southwestern parts of the state. ‘ (National Geographic)