When did they arrive at the St. Croix and what is the National Park Service doing?
Since 1992, the National Park Service has led efforts designed to halt or slow the spread of zebra mussels (Dreissena polymorpha) into the St. Croix Riverway. Prevention activities include education and information, access management, monitoring, planning for remediation and research. Zebra mussels have been found attached to a small number of boats in the St. Croix since 1995. Individual mussels have been discovered scattered in small numbers on the bottom along the lower 25 miles of river. While these animals have had an individual presence on the river for a number of years, a reproducing population had never been discovered on the St. Croix. Unfortunately, that changed during the summer of 2000. For the first time, zebra mussel reproduction was found within the river, along the lower 16 miles or so. The source of reproduction has yet to be pinpointed, but the resulting settlement of juvenile mussels was very disturbing. Park Service and U.S. Fish and Wildlife SCUBA Divers spent thr
