Sinkholes have led to the closure of Sarnia's Sidney Smith Dock on the St. Clair River.
City of Sarnia Construction Manager Robert Williams said crews started filling some small sinkholes last week, but when they were called to fill more in Wednesday, the material was disappearing as soon as it was poured in.
"The Sidney Smith was a steam [powered] lake freighter that was sunk as a dock and was filled with sand and stone, so it seems to be that we've got a leak or a hole in the boat," said Williams.
He said residents are asked to stay away from the area until the severe erosion has been addressed.
"We've closed it off for now and we are looking at our options and investigating what we can do to determine where the material is going. In this case, it's probably a hole in the steel wall and material is disappearing through the wall into the river."
Williams said divers may be brought in to get a better look.
"The material is going somewhere, either into the river or a void within the ship we didn't know about."
The Sidney E. Smith sank in the shipping channel beneath the Blue Water Bridge in June of 1972 after it was struck by another steamer, the Parker Evans.
Sections of the ship were salvaged and towed to Sarnia's shore later that year to become the stone dock at the foot of Seaway Road.