The principal source of machine power for much of Springfield Armory's history, especially in its early years before the installation of steam and electrical power, was water power from a single small tributary of the Connecticut River called the Mill River. This minor tributary river flowed from the east into the Connecticut River on the south side of Springfield and became the site of what came to be known as the Watershops. The large and powerful Connecticut River was too unpredictable and irregular to be useful.

The Watershops were located a mile south of the principal musket assembly site, the Hill Shops. Better and more powerful rivers were located three miles to the north of the Hill Shops [the Chicopee River] and on the west bank of the Connecticut River [the Agawam River], but they were too far away to be of practical use to the Armory.

General George Washington and Colonel Henry Knox noted to the Continental Congress that the location of what became known as the Hill Shops close to the tributary rivers near Springfield was a major point in favor of locating the Continental Army's Arsenal there in 1777. Not until the expansion of the same site as the first national armory in 1795, however, did the U.S. government tap the Mill River to provide power. The destruction by fire in 1805 of the principal water-powered forges and grinding shops, known as the ‘ Lower Watershops ,' led to the construction of a larger and better facility. Explosion and destruction of an older Revolutionary War-era gunpowder mill four years later allowed the Armory to enlarge and raise the height of the dam and to build the ‘Upper Watershops' further upstream Finally, in 1811 and just before the outbreak of the War of 1812. A new and direct road [today's Walnut Street ] was built connecting the Upper Watershops to the Hill Shops a mile to the north.

          In 1817, land was purchased between the Upper and the Lower Watershops to both raise the height of the dam to the Lower Watershops and for the creation of a smaller ‘Middle Watershops.' After a disastrous fire two years later, the Middle Watershops were rebuilt and expanded. A major fire in mid-1825 at the Lower Watershops destroyed most of the new powered stocking machinery requiring rebuilding in stone and brick. This replaced the older oil-soaked wooden structure.

Springfield Armory's Superintendent, Col. Roswell Lee, proposed to the Ordnance Department in 1824 that serious consideration be given, for the sake of future production efficiency, to three proposals: (I) that the entire armory be sold and a new site be established at the powerful Chicopee River [the same site where Ames Sword Company established themselves a half-dozen years later]; (II) that the Hill Shops be closed and rebuilt around the Watershops; and (III) that the existing Armory be extensively rebuilt and expanded.The third option was acted upon and elements of the second plan were realized when the Upper Watershops were eventually expanded and the Lower and Middle Watershops closed in 1857.

Not until 1848 were the roads and bridges associated with the Watershops improved and efforts begun to expand the power pond above the Upper Watershops. By 1857, on the eve of the Civil War, the Lower Watershops had been sold, the Middle and Upper Watershops combined into a single large Watershops complex, and the dam at that site rebuilt and greatly enlarged rising ten feet higher thereby flooding eighty-one acres and creating what has come to be known as Watershops Pond.

Successful Achievement of Mechanized Interchangeable Production