A record number of wildfires burned more than 9 million acres in the U.S. this year, leaving behind charred trees and scorched vegetation. But less-obvious are the impacts they had on the streams and rivers that provide drinking water to urban and rural communities across the country. After a wildfire burns a watershed, rain will carry ash and organic matter into the streams that feed water treatment plants for towns and cities. Utilities must turn off the intake to keep the sediment-filled water from contaminating their systems and switch to another source, if it’s available. New studies found that wildfires can contaminate water for up to 15 years. These findings are especially concerning as climate change has led to an increase in the number and size of wildfires in the U.S.