NOAA

According to NOAA (The US National Oceaonagraphic and Atmospheric Agency), a 20-year study shows that overall contaminant levels in coastal waters of the US are down. US environmental laws, enacted in the 1970s, are likely responsible for this reduction in toxic chemicals, and while there are certainly continuing problems, it's safe to say that there has also been continuing improvement.

The A White Whale Spotted in Alaskan Waters