| Mactaquac Dam | |
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Mactaquac Dam in January 2005 seen from west bank of Saint John River on downstream side. |
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| Official name | Mactaquac Generating Station |
| Country | Canada |
| Location | York County, New Brunswick |
| Coordinates | |
| Status | Operational |
| Construction began | 1965 |
| Opening date | 1968 |
| Owner(s) | NB Power |
| Dam and spillways | |
| Type of dam | Embankment dam |
| Height | 55 m (180 ft) |
| Length | 518 m (1,699 ft) |
| Impounds | Saint John River |
| Spillways | 2 |
| Type of spillway | Concrete |
| Spillway capacity | 16,282.18679 m3 (575,000.000 cu ft) per second |
| Reservoir | |
| Creates | Mactaquac Headpond |
| 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 the Canadian province of 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.
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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 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 St. John River, linking provincial highways 102 and 105 on the south and north sides of the river.
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. An 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 Headpond. 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 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.