In 1991 the New Zealand mud snail was discovered in Lake Ontario in the Great Lakes, and by 2006 had spread to Duluth-Superior Harbour and the freshwater estuary of the Saint Louis River.
The New Zealand mud snail was discovered in Lake Ontario in the Great Lakes. This was in 1991. The New Zealand mud snail by 2006 had spread to Duluth-Superior Harbour. This was in 1991. The New Zealand mud snail by 2006 had spread to the freshwater estuary of the Saint Louis River. This was in 1991.