The first commercial structures erected by settlers as they moved west from the eastern footprint of the pre French and Indian War colonies was usually a mill. Water powered the machinery to grind crops or saw timber. That water flowed from streams that were subject to seasonal and climatic variables. To insure a steady flow of water for the mills, dams were constructed to hold back and direct he flow when water was abundant. My father’s family from NW PA lived in the miller’s house and I spent many days in and around that mill pond and my grandfather spent a good bit of his meager preacher’s salary on concrete to repair the dam that was built by the first settler’s there in 1799.
Recently, I took a pleasant 5 mile training hike along the north shore of Lake Nockamixon here in SE PA. At the loop turnaround are the remains of an early mill dam and pond, out of use for years but still standing.