Ascutney Mill Dam, also known as the Windsor Upper Dam and the Mill Pond Dam, is an arch-gravity dam which is one of the oldest and among the earliest storage dams in the United States. It is made of cut

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

and is located in

Windsor, Vermont Windsor is a town in Windsor County, Vermont, United States. As the "Birthplace of Vermont", the town is where the Constitution of Vermont was adopted in 1777, thus marking the founding of the Vermont Republic, a sovereign state until 1791, when ...

in Windsor County near the

Connecticut River The Connecticut River is the longest river in the New England region of the United States, flowing roughly southward for through four states. It rises 300 yards (270 m) south of the U.S. border with Quebec, Canada, and discharges into Long Isl ...

, where it functioned as a source of

hydropower Hydropower (from Ancient Greek -, "water"), also known as water power or water energy, is the use of falling or fast-running water to Electricity generation, produce electricity or to power machines. This is achieved by energy transformation, ...

and, later,

hydroelectric power Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

. It is on the

ASCE The American Society of Civil Engineers (ASCE) is a tax-exempt professional body founded in 1852 to represent members of the civil engineering profession worldwide. Headquartered in Reston, Virginia, it is the oldest national engineering soci ...

list of historic civil engineering landmarks __NOTOC__ The following is a list of Historic Civil Engineering Landmarks as designated by the American Society of Civil Engineers since it began the program in 1964. The designation is granted to projects, structures, and sites in the United Stat ...

since 1970 and is listed on the

National Register of Historic Places The National Register of Historic Places (NRHP) is the Federal government of the United States, United States federal government's official United States National Register of Historic Places listings, list of sites, buildings, structures, Hist ...

(as Ascutney Mill Dam Historic District) since January 09, 2007. The dam is built in the valley of the Mill Brook, a right tributary of the Connecticut River. The pond above the dam is known as the Mill Pond. The Ascutney Mill Dam Company was formed to build the dam. Construction began in June 1834, and was finished in November. The purpose of the dam was to regulate seasonal water flow and provide hydropower for nearby

sawmill A sawmill (saw mill, saw-mill) or lumber mill is a facility where logging, logs are cut into lumber. Modern sawmills use a motorized saw to cut logs lengthwise to make long pieces, and crosswise to length depending on standard or custom sizes ...

s and gristmills, which previously could not operate during periods of low water flow in Mill Brook. The dam allowed water to be stored in the impound during the winter for release during lower flow seasons. Ithamar A. Beard was a New England engineer who surveyed the area and selected the site for the dam. Simeon Cobb and Joseph Mason were the contractors in charge of building the dam.Jackson, Donald C. ''Great American Bridges and Dams'', John Wiley & Sons, New York (USA), , 1984; pp. 106–107.

Background

History and planning

As early as 1767, several sawmills and gristmills were operating along the banks of Mill Brook in Windsor. However, during periods of low water flow the mills stood idle. Like many early towns, their location was often selected on the availability of such a resource. Water-powered mills have been used to save human labor since ancient times, but like all renewable energy resources, their power is not always available when needed. Sawmills were needed to provide boards for construction, and gristmills were necessary to ground grain into flour. In post-colonial Vermont, these mills were essential for the building and food supply needs of the growing cities. The Ascutney Mill Dam Company was formed in 1833 to build the dam; it was the owner and was responsible for the dam's maintenance and operation. Despite problems during the financial

panic of 1837 The Panic of 1837 was a financial crisis in the United States that began a major depression (economics), depression which lasted until the mid-1840s. Profits, prices, and wages dropped, westward expansion was stalled, unemployment rose, and pes ...

, the company continued to operate the dam throughout the 19th century. Ithamar A. Beard was the engineer who surveyed the area and made the suggestion for the dam site. The dam was constructed from mid-April 1834 to mid-November 1834. It was built of cut granite and was one of the first gravity-arch dams built in the United States. It is possibly the oldest

masonry dam Masonry dams are dams made out of masonrymainly stone and brick, sometimes joined with mortar. They are either the gravity or the arch-gravity type. The largest masonry dam in the World is Nagarjuna Sagar Dam, Andhra Pradesh and Telangana, in ...

in the U.S. of any significant size. The original dam had a near-vertical downstream face built in an arch form. Water filled up behind the dam each winter and was allowed to flow over the spillway the following spring. Water and ice falling over the crest and to the ledge below caused noise and vibrations throughout the village which concerned citizens. Inspections found that the vibrations caused no damage to the dam, but a stone buttress was built below the dam to stop the vibrations.

Construction

Construction began in April 1834. Simeon Cobb and Joseph Mason were the contractors in charge of building the dam, and

Allen Wardner Allen Wardner (December 13, 1786 – August 29, 1877) was a Vermont banker, businessman and politician who served as State Treasurer. He was also the father-in-law of Attorney General, Secretary of State and United States Senator William M ...

, a prominent Windsor businessman and banker, superintended the work. The first step was to remove a small dam on the site. In June the first granite blocks were placed. The granite was obtained from nearby quarries. The overall construction was fairly simple and finished in November 1834, just seven months after construction began. The finished product was a high and long dam. The elevation above mean sea level is .

Condition

The National Program for Inspection of Non-Federal Dams performed an inspection of the dam in September 1978. The report was a Phase I inspection report from the Corps of engineers in

Waltham, Massachusetts Waltham ( ) is a city in Middlesex County, Massachusetts, United States, and was an early center for the labor movement as well as a major contributor to the Technological and industrial history of the United States, American Industrial Revoluti ...

, New England division. The abstract of the report writes: "The dam is considered to be in fair condition. The dam is believed to be safe under normal operating conditions. The test flood is the PMF. It is recommended that the owner engage the services of a qualified consultant to evaluate the stability of the dam. In addition to long term recommendations, there are several remedial measures which should be implemented." The current policy of the state of Vermont Department of Environmental Conservation requires that only dams that are capable of impounding more than need to be inspected. The Upper Windsor Dam does not fall within this category. In the twentieth century, a concrete coping was placed on top of the structure to help ensure its stability in times of flood. The dam retains much of its original structure even though it is one of the oldest dams in the United States.

Topographic information

For the

United States Geological Survey The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on Mar ...

(USGS), the dam is sourced in the Windsor Windsor quad. The topographic map shows the mountainous terrain of the area. In fact, Windsor County, Vermont is home to a total of 202 mountain summits and peaks. The highest is Gillespie Peak which is at an elevation of above sea level. The peak flow in the rivers near uneven terrain could fluctuate vastly between periods of high and low precipitation because much of the rainfall flows down to a discharge rather than infiltrating into the ground as it would in flat terrain. This flow could cause a large increase in flow rate and river height in a fairly small amount of time. The fact that the Connecticut River was just a few miles away also played a role in this. Because of all this, the timing of opening and closing the dam to regulate flow and produce hydroelectric power was important.

Nearby areas

Fishing

The Windsor Upper Dam area is a popular fishing spot, both

fly fishing Fly fishing is an angling technique that uses an ultra-lightweight lure called an artificial fly, which typically mimics small invertebrates such as flying and aquatic insects to attract and catch fish. Because the mass of the fly lure is in ...

and baitcasting. Local fish include

bluegill The bluegill (''Lepomis macrochirus''), sometimes referred to as "bream", "brim", "sunny", or, in Texas, "copper nose", is a species of North American freshwater fish, native to and commonly found in streams, rivers, lakes, ponds and wetlands ea ...

brook trout The brook trout (''Salvelinus fontinalis'') is a species of freshwater fish in the char genus ''Salvelinus'' of the salmon family Salmonidae native to Eastern North America in the United States and Canada. Two ecological forms of brook trout h ...

and

rock bass The rock bass (''Ambloplites rupestris''), also known as the rock perch, goggle-eye, red eye, and black perch, is a freshwater fish native to east-central North America. This red-eyed fish is a species of freshwater fish in the sunfish family (bi ...

. Fishing is open to the public but a Vermont fishing license is required.

Footnotes

External links

* {{Authority control Dams in Vermont Historic districts on the National Register of Historic Places in Vermont Federal architecture in Vermont Infrastructure completed in 1783 Dams completed in the 18th century Historic Civil Engineering Landmarks Dams completed in 1834 Buildings and structures in Windsor, Vermont National Register of Historic Places in Windsor County, Vermont