Shipping groups from the U.S. and Canada say the annual Float Down event on the St. Clair River puts participants in danger and hinders commercial operations.
The Canadian Shipowners Association and the U.S. Lake Carriers' Association voiced their disapproval of the event in a joint statement Monday.
Lake Carriers' Association president James Weakley said the river is a "federal navigation channel, not a playground."
The unsanctioned event takes place Sunday, with people in tubes and rafts expected to float from Port Huron to Chrysler Beach in Marysville.
Canadian Shipowners Association president Robert Lewis-Manning says the groups decided to come out against the event after a 19-year-old man drowned last year.
Float Down website owner Erik Kimball tells the Times Herald of Port Huron that the river is "for everybody, not just commercial traffic."
The annual event can draw thousands.
