Officials say an invasive water plant called European frogbit has been detected in Michigan's lower Grand River.
The state Department of Environment, Great Lakes, and Energy says the plant was found immediately upstream of Grand Haven in Ottawa County and in Pentwater Lake in Oceana County.
European frogbit first appeared in southeastern Michigan in 1996. It has spread along the coastal areas of Lake Erie and Lake Huron up to the eastern Upper Peninsula.
The plant resembles a miniature water lily with leaves about the size of a quarter. It forms dense mats that prevent native plant growth, make movement difficult for ducks and large fish, and cause problems for boaters, anglers and swimmers.
A survey is underway to determine how far the plant has gone and how to respond.