In 2023, professor Damian Helbling was getting a lot of calls and emails from local residents. The Environmental Protection Agency (EPA) had just announced regulations to limit per- and polyfluoroalkyl substances (PFAS)—some of which have been linked to cancers and other negative health effects—in drinking water. Ithacans and others in the region wanted to know about levels in the ponds, lakes, streams and creeks in their proverbial backyards.