Little background (or read a better writeup here courtesy of Enel, N.A.): The Essex Company, which was the driving force behind Lawrence, using a design attributed to Charles Storrow, began construction of the dam in 1845 and completed it by 1848. The 900-foot-long dam was needed to turn a 5' drop in elevation into a 30' drop in elevation to provide a Lowell-like source of hydropower to the new city. In fact, the new dam created a millpond going all the way upriver to Lowell. For chronological comparison, this is the same time period in which Lowell was building the Northern Canal and Moody Street Feeder - and Lawrence was just getting started. The dam, due to its height and row-after-row of granite blocks, was considered an engineering marvel of its day. Although becoming less useful as the mills it powered shuttered, the strongly-built dam survived.
In the late 1970s, a hydroelectric plant generating nearly 17 MW (smaller than Lowell's 24 MW installation) was constructed on the south side of the dam - the company was still the Essex Company. Enel bought the Essex Company a few years later and took control of the plant (like they did at Lowell). In the last few years, the old pin-and-5' wooden flashboard system Lawrence, like us, had used for well over a century, was replaced with a bladder dam similar to the one proposed for Lowell. The flow rate is currently fairly low and water is not going over the dam, so it's a good time to see what it really looks like. I'll let the pictures speak.
|Great Stone Dam|
P.S. Something Lawrence has that I thought was pretty cool that was also part of this trip: The Antiques Mall over on Canal Street. Why does a city so interested in history like Lowell is not have much of an antique industry?