Federal divers have found a large infestation of zebra mussels on the Saint Croix River. The mussels were discovered last week on the lower end of the river, north of Prescott, Wisconsin. It's the first significant foothold by the mussels in the federally protected river. Jay Rendall is the exotic species program coordinator for the D-N-R. He says the Saint Croix has been considered a high risk location because it is so close to the infested Mississippi: