This image shows two of the three main cascades of the lower falls. The color of the water as it passes over the falls here is a result of tannin released by leaves falling into the river along its course.
The description on the back states:
LOWER TAHQUAMENON FALLS
In Michigan’s Upper Peninsula
Sometimes referred to as “the root beer falls”. It is an interesting fact that actually there is a greater volume of water going over the lower falls than the upper. Many people enjoy wading in the shallow waters beneath the falls.
–The postcard is dated 1953, but it was mailed and postmarked 1964.