This article on the United States Geological Survey (USGS) website summarizes the findings from a comprehensive assessment of mercury in waterways across the nation. As the article mentions, mercury, which can travel long distances in the atmosphere, is often the product of coal burning for energy production. In the study featured here, about one in four of the predator fish sampled exceeded EPA guidelines for safe consumption. Readers who would like to learn more may access a number of resources on the site, including the full 100-page report, and over a dozen Related Headlines from around the USGS site.