This image shows a small section of rapids on the Current River as it flows into Boulevard Lake in Ontario, Canada.
Alutone Reproductions by E. S. & A. Robinson (Canada) Limited, Leaside, Ontario
The description states:
CANADIAN LAKE SUPERIOR CARD SERIES
The Current River flowing into Boulevard Lake
Port Arthur, Ontario
–Port Arthur is on the northwestern shore of Lake Ontario, not far from the Minnesota border.
This image likely dates from the 1950s.