Over a distance of 1.2 miles, in the center of Bennington, New Hampshire, the water level of the Contoocook River drops seventy feet. The glacier that retreated around 10000 years ago formed the terraced landscape over which the river flows. That source of power at the “Great Falls of the Contoocook” is what induced Joseph Putnam in 1782 to purchase land on the east side of the river for the construction of a grist mill [a mill for grinding grain into flour]. At that time, there was no town called Bennington in the state — the land was in the town of Hancock. In the 1700s, the energy of falling water was the principle source of power for machinery. Settlers in the Americas were always looking to live where there was water tumbling down the smallest incline. At the Great Falls, there was not a single ‘falls’ like Niagara, but a series of four locations where the water went down hill, falling 10-12 feet at each site. This series of rapids falls over the remains a glacial moraine, which was breached by a tremendous flow of water at the end of the last Ice Age.
To harness the power, dams had to be built. For the purpose of discussion, I have numbered the dams 1 through 4, to show their position on the river, not the order in which they were built. Dam 1, the Powder Mill Dam, is the farthest South, which is upstream of the town. In 1823, the Dam was built at the North end of Powder Mill Pond, creating that large body of water. Dam 3, called the Pierce Dam, is the oldest, built by Putnam. Joseph Putnam’s dam was downtown, across the road from his house. [on the Google Map that is shown in the link, the dam is just above the words ‘common place’] Just upstream from that is Dam 2, known as Monadnock Dam. High Gate Dam, #4, is down-stream, across from Alberto’s Restaurant, near the Monadnock Paper Mill. None of these spillways looks terribly dramatic, but together they store a lot of potential energy which powered many big and little mills around the town in the 1800s and early 1900s. Since 1932, there has been a hydroelectric plant at Pierce Dam. Falling water is still a source of energy.
The next post will be on March 27, 2023.