1906 Wachusett Dam on Nashua River and Aban B&M Trestle and Tunnel in Clinton, MA

Dam: (Satellite, 1,198 photos)

Tunnel, West Portal: (Satellite, 649 photos)

The dam was built in 1906 as part of a water supply. Dogs are not allowed in the parks because the 65 billion gallon reservoir is a water supply. The reservoir "covers 108 square miles with 37 miles of shoreline." [mass]

"At the time of construction, the Wachusett Reservoir was the largest in the world. It remains a great engineering feat and is one of the few unfiltered water supplies in the country. " [Mass_reservoir]

Brian Hale, Aug 2013

Peter Brinley posted
No longer in service, Hydroelectric Turbines at Wachusett Dam in Massachusetts.

 Mass_dam
"The Wachusett Dam maintains the honor of being the largest hand built gravity dam in the world. Constructed of granite masonry, the dam stretches 944’ [288m] across." The height of the dam is 115' (35m) above ground and 112' (34m) below. It tapers from 22.5' (6.9m) at the top to 185' (56m) at the bottom. The spillway is  452' (138m) long.

Mass_dam

I found the spillway on the north side after I saw some photos of it.

Clay Mangiameli, Oct 2023

Did the power plant quit running when they turned the tailrace into a fountain?

Anthony Trinciante, Sep 2022

Actually, there was no outlet at the base of the dam because the spillway is on the side and the normal flow is diverted into an aqueduct as a water supply. This map also shows were the trestle crossed the river when the Boston & Maine tracks were rerouted around the dam site.

1952 Clinton Quad @ 24,000

The top middle diagram shows that there is more of the dam underground than above.

DigitalCommonwealth

In 1907, because of a landslide, they had to build a 2-mile (3.2km) long dike.

Satellite

Mass_dike