The Ben Smith Dam is located on the Assabet River in Maynard, Massachusetts. The Assabet River is located approximately twenty miles west of Boston. Nine dams are located along the thirty-two mile northeastern span of the river – the largest being the Ben Smith Dam. It was built in the early 1900’s by Armory Maynard to store the Assabet River waters for the town mill. The dam is approximately 51m long (170 ft.) and 3m high (9.5 ft.), impounding a reservoir of approximately 18.75-acres. A 485m (1600 ft.) power canal and culvert leads to a gatehouse with manually controlled gates, then downstream of the gatehouse to an 18.3-acre upper and lower millpond system. A view of the dam is shown below.

When the project was operated for power production, the water was diverted from the impoundment created by the dam into the power canal, through the gatehouse and ponds, into an intake/trashrack structure and through a 15m (49 ft.) long, 2m (7 ft.) diameter steel penstock to a powerhouse.

After leaving the powerhouse, the water passed through twin 90m (300 ft.) long tailrace tunnels to rejoin the Assabet River about 1635m (5400 ft.) downstream of the Ben Smith Dam. The project’s total installed capacity was 125 kilowatts. In the 1980’s Digital Equipment Corporate was issued an exemption to produce hydroelectric power for the 45-acre commercial office complex (originally called Maynard Mill, now called Clock Tower Place). The office complex was eventually sold and generation ended in the early 1990’s. The current owners are pursuing an exemption to resume hydroelectric generation at the site. One of the key requirements however is maintenance of a minimum 39 cubic feet per second (cfs) water flow down the Assabet River to maintain downstream aquatic habitat.