Mactaquac Dam

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Mactaquac Dam
Mactaquac Dam in January 2005 seen from west bank of Saint John River on downstream side.
Mactaquac Dam is located in New Brunswick
Mactaquac Dam
Mactaquac Dam in New Brunswick.
Official name Mactaquac Generating Station
Country Canada
Location Bright Parish / Kingsclear Parish, York County, New Brunswick
Coordinates 45°57′15.2″N 66°52′5.8″W / 45.954222°N 66.868278°W / 45.954222; -66.868278Coordinates: 45°57′15.2″N 66°52′5.8″W / 45.954222°N 66.868278°W / 45.954222; -66.868278
Status Operational
Construction began 1965
Opening date 1968
Owner(s) NB Power
Dam and spillways
Type of dam Embankment dam
Impounds Saint John River
Height 55 m (180 ft)
Length 518 m (1,699 ft)
Spillways 2
Spillway type Concrete
Spillway capacity 16,282.18679 m3 (575,000.000 cu ft) per second
Creates Mactaquac Headpond
Total capacity 1,307,491,000 m3 (4.61736×1010 cu ft)
Surface area 83.85 km2 (20,720 acres)
Max. water depth 39.624 m (130.00 ft)
Power station
Type Run-of-the-river
Hydraulic head 31.7 m (104 ft) - 35.4 m (116 ft)
Turbines 6 x Kaplan
Installed capacity 653 MW

The Mactaquac Dam is an embankment dam used to generate hydroelectricity in Mactaquac, New Brunswick. It dams the waters of the Saint John River and is operated by NB Power with a capacity to generate 653 megawatts of electricity from 6 turbines; this represents 20 percent of New Brunswick's power demand.


Formally called the Mactaquac Generating Station, the dam and power house are located approximately 15 km (9.3 mi) upstream from the city of Fredericton. The dam is an embankment dam consisting of a rock-fill structure sealed by clay. It combines with two concrete spill-ways to form an arch across a narrow section of the river between the communities of Kingsclear on the west bank, and Keswick Ridge on the east bank.


Rising 40 metres in height above the river level, the reservoir (referred to locally as the "head pond") covers 87 square kilometres and extends 96 kilometres upstream, near Woodstock. The dam and powerhouse are a "run of the river" design, meaning that the reservoir has no additional holding capacity in the event of unusually high water flows, such as during the spring freshet.

The concrete portions of the dam (namely the spill-ways) are currently experiencing a problem of expanding concrete. When built, locally quarried greywacke was used as the aggregate and is believed[by whom?] to be responsible for the alkali-aggregate reaction expansion. The dam is being monitored and extra maintenance work is being performed, although the spill-way is expected to have a reduced life expectancy. The earliest projections put the dam's end-of-life at 2028, instead of the original 100-year lifespan of 2068. Even worse, the officials will not say how much it will cost and when it will show up on the utility's accounts.[1]

Kingsclear, NB is also the site of an Atlantic Salmon fish hatchery, located immediately downstream from the dam. The Mactaquac Dam also has a fishway to catch salmon and transport them upriver.

The dam also serves as a locally important public road bridge across the Saint John River, linking provincial highways 102 and 105 on the south and north sides of the river.

Mactaquac Dam in January 2005 from downstream side showing spillway

Flooding of the Mactaquac Lake[edit]

Electrical generation began in 1968 after the reservoir had completely filled. The flooding of the valley resulted in the displacement of several thousand residents and land owners in areas such as Bear Island and other small communities, as well as the abandonment of a Canadian National Railway line and numerous local roads and several communities. A historic waterfall was also submerged as the reservoir filled.

The planned town of Nackawic, New Brunswick and the nearby Ste-Anne-de-Nackawic pulp and paper mill were built to accommodate the new reservoir and power opportunities.

Following the success of preserving historic buildings at Upper Canada Village when the upper St. Lawrence River valley was flooded by the Long Sault Dam, the government of New Brunswick created the King's Landing Historical Settlement to save several buildings which would otherwise have been flooded by the Mactaquac Lake. Mactaquac Provincial Park was also created as a result of the dam. The recreational facilities and economic development created by dam-associated development are said[by whom?] to be inspired by the Tennessee Valley Authority, which undertook several similar projects in the 1930s, during the Great Depression, in the southern United States.

Inspiration for Arts and Culture[edit]

The building of the dam was the inspiration for Riel Nason’s 2011 novel 'The Town that Drowned', published by Goose Lane Editions. The fictional book, winner of the 2012 Commonwealth Book Prize, is set in the 1960s near Pokiok Falls, where the characters learn their homes will soon be swallowed by the rising water.


  1. ^ "Report says Mactaquac Power Station in trouble". December 11, 2000. Retrieved 1 October 2010. 

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