We have several of those around my place. In 1855 the surveyor who documented the Donation Land Claim took a sight and noted "on this line lies Hudson's Saw Mill." About 30 years ago I poked around the area indicated and found the remains of a saw blade still attached to a shaft.
We have a photo of the man who my grandfather bought the property from. He had been the foreman of the logging operation for the original landowners (who were partners with Hudson) and had married their oldest daughter. The photo shows them skidding logs with oxen and rolling them into a log sluice (ditch) which emptied into a pond that held the logs, then floated them down another ditch to the mill, and also ran the water wheel that powered the mill. The first ditch and the pond still are in operation. I cleaned out the ditch two years ago with a small excavator, and when I removed the accumulated silt the ditch is 8' wide and 4' deep!
I have no doubt that the rafting dogs were used in moving the logs to this mill.