Moore Dam is a major
hydroelectric dam
Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...
on the Upper
Connecticut River between
Grafton County,
New Hampshire
New Hampshire is a state in the New England region of the northeastern United States. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec to the nor ...
and
Caledonia County,
Vermont
Vermont () is a state in the northeast New England region of the United States. Vermont is bordered by the states of Massachusetts to the south, New Hampshire to the east, and New York to the west, and the Canadian province of Quebec to ...
in the northeastern
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
. The dam is located near
Littleton, New Hampshire
Littleton is a town in Grafton County, New Hampshire, United States. The population was 6,005 at the 2020 census. Situated at the northern edge of the White Mountains, Littleton is bounded on the northwest by the Connecticut River.
The main vil ...
, and forms the
Moore Reservoir. The Moore Station is the largest conventional hydroelectric plant in
New England
New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the Can ...
, in terms of installed capacity and average power generation. The dam and reservoir also provide flood control, recreational boating and fishing.
The official name of the dam is the Samuel C. Moore Dam, after a former president of the now defunct
New England Power Company that originally built it. The dam, reservoir and power station are now owned and operated by
TransCanada Corporation
TC Energy Corporation (formerly TransCanada Corporation) is a major North American energy company, based in the TC Energy Tower building in Calgary, Alberta, Canada, that develops and operates energy infrastructure in Canada, the United States, ...
.
History
The Moore Dam is the uppermost feature of the Fifteen Miles Falls hydroelectric project, which began development in the early 1900s by New England Power (later USGen New England). Before damming, the "Fifteen Miles Falls" was a fast flowing
whitewater
Whitewater forms in a rapid context, in particular, when a river's gradient changes enough to generate so much turbulence that air is trapped within the water. This forms an unstable current that froths, making the water appear opaque and ...
section of the Connecticut River, where it dropped over the course of , making it the longest single stretch of whitewater in the northeastern US.
The steep grade and heavy flow also made it ideal for the construction of water mills, and later, hydroelectric plants. In 1908 Carl A. Ross of Littleton pitched the proposal to Massachusetts investors who agreed to finance the project.
The two lower plants,
Comerford Dam downstream and
McIndoe Dam downstream, were completed in 1930 and 1931 respectively.
Site preparations for Moore Reservoir commenced in the mid-1930s, with the clearing of over 3,000 acres of farmland and forest to allow for future flooding. The towns of Upper Waterford, Vermont and Pattenville, New Hampshire were demolished; however, with the onset of the
Great Depression preliminary work on Moore Dam was halted. Construction was not resumed until 1954, and was completed in 1956, at a cost of $41 million.
The dam was dedicated, and power generation begun, on June 20, 1957.
The embankment section of the dam has experienced seepage problems at several points in its lifetime, the first during the 1980s, which was corrected in 1996 with the construction of a drainage system. The leak re-emerged in 2009 and 2010, when it was discovered that water was leaking between the dam structure and the original ground surface, requiring extensive re-construction and filling work.
In 2005 USGen New England filed for bankruptcy, and
TransCanada purchased Moore Dam and 13 other hydroelectric stations for the sum of $505 million. As of 2016, TransCanada intends to sell the dam to local utilities in Vermont and New Hampshire.
Operations
While most dams along the Connecticut River have small reservoirs, capable only of regulating daily fluctuations in water level, Moore Dam has a large storage capacity used both to regulate river flows on a seasonal basis, and to generate
peaking power on demand. Along with Comerford Dam, it helps reduce spring floods due to snowmelt, at the same time capturing water for use during drier parts of the year. During the late fall or winter, the reservoir is drawn down to provide space for the incoming snowmelt. The snowpack is measured throughout the winter and reservoir levels are adjusted up or down based on these measurements.
The typical seasonal draw down is between .
Due to its size and security requirements, Moore Dam is one of only two dams in New Hampshire that has a human operator living on-site (the other being the
Murphy Dam).
Statistics
Moore Dam is a composite earthen and concrete dam located upstream from where the Connecticut River meets the
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
. The dam is tall and long, with a central concrete section flanked by of embankments. The
spillway
A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure th ...
is located on the concrete section and is controlled by four gates: a
sluice gates
Sluice ( ) is a word for a channel controlled at its head by a movable gate which is called a sluice gate. A sluice gate is traditionally a wood or metal barrier sliding in grooves that are set in the sides of the waterway and can be considered ...
, and three
tainter gate
The Tainter gate is a type of radial arm floodgate used in dams and canal locks to control water flow. It is named for Wisconsin structural engineer Jeremiah Burnham Tainter.
A side view of a Tainter gate resembles a slice of pie with the ...
s.
The spillway is designed to handle ; however, a 1983 study indicated the
probable maximum flood at this site is , which could overtop the earthen part of the dam.
The power station is located at the base of the dam and consists of four 56,400 horsepower turbines each powering a generator rated at 35,100
kilowatts (kW). The rated capacity of the plant is 140,400 kW at a flow of , and the overload capacity is 191,960 kW at a flow of . Each turbine is supplied with water by a long penstock affording a gross
head of and a maximum of .
In 2009, the Moore Station generated 314,300
megawatt hour
A kilowatt-hour ( unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bi ...
s (MWh).
The average generation of the whole Fifteen Mile Falls project (Moore, Comerford and McIndoe dams combined) was 662,947 MWh for the period 1999–2009.
The reservoir has a total storage capacity of and a full surface area of .
The
watershed area above the reservoir, measured at a
U.S. Geological Survey
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and ...
stream gauge at
Dalton, New Hampshire
Dalton is a town in Coös County, New Hampshire, United States. The population was 933 at the 2020 census. It is part of the Berlin, NH– VT Micropolitan Statistical Area.
History
Dalton was incorporated in 1764 under the name "Chiswick ...
, is . The mean annual flow of the Connecticut River at this point is , with a monthly high of in April, and a low of in August.
Environmental impacts
For decades before the dams were built, paper mills and factories along the Connecticut River had been dumping their waste in the river; each spring, floods would flush the contaminants towards the ocean. When Moore Dam was constructed the mill waste was trapped in the reservoir where it settled into the lake bottom sediment creating highly
anoxic
The term anoxia means a total depletion in the level of oxygen, an extreme form of hypoxia or "low oxygen". The terms anoxia and hypoxia are used in various contexts:
* Anoxic waters, sea water, fresh water or groundwater that are depleted of diss ...
conditions. For many years, the reservoir was essentially devoid of aquatic life below a depth of or so, although this has slowly improved due to the closing of many industries that originally discharged their waste in the river, and the installation of sewage treatment systems in rural areas. However, fish populations must still be replenished each year by artificial stocking.
Because the downstream McIndoe Dam posed a total barrier to both upstream fish migration in the Connecticut River, neither the Moore or Comerford dams was built with fish passage facilities.
The great height of the dam precludes the installation of structures such as
fish ladder
A fish ladder, also known as a fishway, fish pass, fish steps, or fish cannon is a structure on or around artificial and natural barriers (such as dams, locks and waterfalls) to facilitate diadromous fishes' natural migration as well as move ...
s and has posed an obstacle to restoring salmon runs in the Connecticut River, as the best spawning areas for salmon are located in the
headwaters
The headwaters of a river or stream is the farthest place in that river or stream from its estuary or downstream confluence with another river, as measured along the course of the river. It is also known as a river's source.
Definition
The ...
area upstream of the dam.
Recreation
Moore Reservoir is one of the largest "undeveloped" lakes in New England, with few private homes or businesses along its shores. The reservoir area is owned by
TransCanada, which permits public access.
There are four boat ramps on the New Hampshire side of the reservoir and one directly below Moore Dam. The dam has
portage facilities on both the Vermont and New Hampshire sides for use by canoeists and kayakers. Fish species found in the lake include salmon, trout, pike, pickerel, perch, bass and sunfish.
/ref> Because of the reservoir's great size and catchment area, it is subject to waves and particularly large amounts of floating tree trunks and debris.
See also
* List of dams and reservoirs in New Hampshire
*List of dams and reservoirs in Vermont
Following is a list of dams and reservoirs in Vermont.
All major dams are linked below. The National Inventory of Dams defines any "major dam" as being tall with a storage capacity of at least , or of any height with a storage capacity of .
D ...
References
{{Reflist
External links
Current water release schedule at TransCanada dams
Dams in Vermont
Dams in New Hampshire
Dams completed in 1956
Earth-filled dams
TC Energy dams