The notion that septic tanks prevent fecal bacteria from seeping into rivers and lakes simply doesn't hold water, says a new Michigan State University study. Water expert Joan Rose and her team of water detectives have discovered freshwater contamination stemming from septic systems. Appearing in the Proceedings of the National Academy of Sciences, the study is the largest watershed study of its kind to date, and provides a basis for evaluating water quality and health implications and the impact of septic systems on watersheds.