| British Columbians have been building dams since the turn of the century. The period of greatest activity occurred in the 1950's, 60's, and 70's when BC pursued an aggressive program of large-scale dam construction. Hydroelectric power production (for domestic use and export) was the major purpose of these large-scale dams. |
Most British Columbians embraced dam construction in the post-war period as a positive step toward economic prosperity. That began to change in the 1970's as residents witnessed the serious environmental and social costs of dams. The decline of fish stocks and the permanent drowning of productive farmland, valley-bottom forest, scenic canyons, and (in some cases) entire towns fueled a growing public opposition to new dams. During the 1970's and 80's, grass-roots lobbying blocked the construction of new dams on the Skagit, Stikine, and Peace rivers.
Recently, BC's provincial government responded to public opinion by legislatively protecting important salmon rivers against future dams under the Fish Protection Act. In addition, BC has embraced two important programs — the "BC Heritage Rivers System" and the "Canadian Heritage Rivers System" — which officially commemorate BC rivers that represent outstanding values of provincial and national significance. These values include history, culture, economy, recreation, and ecology. |
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| The Grand Canyon of the Stikine River (right) was once targeted for a large hydroelectric dam (above), but growing public opposition helped to stop the project. The Stikine is now proclaimed as a "Heritage River" both provincially and nationally, and the river is legislatively protected against any future dams on the mainstem. |
(Photo: Gary Fiegehen) |
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| Given the public controversy that surrounds large-scale dams, there is a need to pursue alternatives. Small dams, built at appropriate locations, can generate power while minimizing environmental impacts. New technologies also exist which enable small turbines to harness the power of a stream without building any dams at all. Most importantly though, society must continue to move toward curbing consumption.
BC Hydro's "
Power Smart
" program is one attempt to educate the public about wise energy use, and this will hopefully reduce the rate of future demand. |
(Photo: Gary Fiegehen) |
British Columbia's Revelstoke Dam
under construction in the 1980's.
This was BC's last large-scale
dam project. |
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Dams have been built for a range of purposes and are managed by a variety of entities, including
BC Hydro
(a provincial crown corporation), private corporations, municipalities, and private citizens.
Dams are built to provide one or more of the following benefits to society:
- Drinking water
- Irrigation
- Hydroelectricity
- Flood control
- Industrial use
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There are more than 2,000 dams in British Columbia, including both small and large structures. The vast majority are relatively small — only 196 dams are higher than 9 metres.
Following are four major types of dam structures. The photo examples show large-scale structures, but the same design principles may be applied to smaller dams. Depending on the size of dam, construction materials may include earth, rock, steel, concrete, wood cribbing, or a combination of several materials. |
Earth Dams (Embankment Dams):
Built from earth and rock, these dams are massive, depending on their weight and great width to hold back the force of water. Most BC dams are earth dams, particularly the many small-scale structures under 9 metres. |
W.A.C. Bennett Dam, BC.
(Photo: Gary Fiegehen) |
Gravity Dams:
Gravity dams resist the horizontal force of water entirely by their own weight. Narrower than earth dams, they require enormous amounts of concrete, making them expensive to build. |
Tygart Dam, Pennsylvania.
(Photo: US Army
Corps of Engineers) |
Buttress Dams:
Buttress dams require less concrete by using supports, or buttresses, along the dam's downstream face. These dams take many forms, with the face sometimes appearing flat or curved. |
Anyox Dam, BC.
(Photo: Gary Fiegehen) |
Arch Dams:
Arch dams are curved, using the strength of the arch to hold back water. The arch shape allows these dams to be thinner than any other type, however, this design requires narrow canyons with strong abutments. |
Boundary Dam, Washington.
(Photo: Seattle City Light) |
Good Links!
For more information on the engineering principles behind dam design, and fascinating photos of historic dam failures, visit: |
| Cracking Dams —
http://simscience.org/cracks/advanced/mintro.html |
| Canadian Dam Association —
http://www.cda.ca/ |
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| All dams impound or divert water and therefore require a water licence from the provincial government. However, many small dams have been built by private citizens without proper approvals and licensing. This is a concern, particularly in terms of public safety, as even small dams can cause serious property damage, environmental damage, and loss of life if they fail. Aside from failure risk, these small unlicensed dams may also block the passage of fish upstream. |
| In all cases, dam owners are clearly responsible for the safe operation and maintenance of their dams. Under the provincial Water Act, a dam owner is held financially liable for any damage to land and property resulting from failure of their dam. |
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