A dam built in 1920 replaced a wooden one constructed in 1883 to supply power to the Cotton Mill downstream owned by Exeter Manufacturing Company. It is 422 feet long, 21 feet high, and has an ogee spillway of 139 feet. Two gate operating mechanisms were located above the east abutment of the dam. Manufactured in Keene by L. B. Dow, Inc., they had to be operated manually by rotating two large wheels in the front. It took approximately four hours for two men to raise or lower the gates in high water. During the “Mother's Day Flood” of 2006, the gears were stripped, and because of this and other problems with their operation, the State of New Hampshire replaced them with more modern apparatus that can be operated manually.