You’re talking about PFAS and the host of per-fluorinatid acids that are being produced. Essentially, these are found in waterproof clothing (DWR textile), non-stick pans, fire extinguisher and a host of other household items (even food wax paper wrappers). These don’t break down and are now found everywhere. Human health outcomes are reduced as a result. Not sure if they accumulate in lakes, but we know they’re present throughout the world - even in the Arctic regions.