by Patrick McCully, Executive Director, International Rivers
Dams do not live forever. A dead or dying dam may have silted up, stopped
producing electricity, or become increasingly unsafe, at which point it
may be a candidate for removal. Not all dams slated for removal are
targeted for safety reasons, however: another major reason prompting
activists to call for the removal of dams is the decimation of fisheries.
Although dams have been found unsafe or destructive of fish habitat in
many parts of the world, few major dams have yet to be removed. The
engineering of dam removal is still young and untried, and the cost of
dam-removal is still ignored when construction costs are estimated. How
exactly to dismantle a very large dam, what to do with the sediment
clogging the reservoir behind it, and how much such an operation would
cost, is largely unknown. Removing a hydrodam could even cost more than
building one, especially where reservoir sediments contain heavy metals
and other toxic contaminants.
But momentum is building to remove
more dams, and to find the best ways to take them down and restore the
rivers they impounded. Dam removal campaigns are now underway in many
parts of the world, some of which target very large dams. Currently, the
United States - with some 74,000 dams (most of which are relatively small)
- has perhaps the most active dam-removal movement. Grassroots groups
around the country have launched campaigns to dismantle dams in their
communities, and hundreds of small- and medium-sized dams have already
come down. Another sign of progress is that the American Society of Civil
Engineers just published technical guidelines for dam removal - the first
important sign that the dam-building industry is beginning to take this
issue seriously.
Old Dams
Safety concerns have been the most common reason for dam removals. Dams
age at a different rates and in a different way, depending on a variety of
circumstances. Some dams may remain safe for a thousand years, others may
start to crack and leak after less than a decade. Around the world, some
5,000 large dams are now more than 50 years old, and the number and size
of the dams reaching their half century is rapidly increasing. The average
age of dams in the US is now around 40 years. Between 1977 and 1982 the
Army Corps of Engineers inspected 8,800 non-federal dams in the US, most
of them privately-owned, which it classified as "high-hazard" -
where a failure could cause significant loss of life. One-third of these
dams were considered "unsafe," primarily because of inadequate
spillway capacity. A 1994 survey showed at least 1,800 non-federal dams
were still unsafe. The situation is similar for federal dams: in 1987
one-fifth of BuRec’s 275 dams were classified as unsafe, as were one-third
of the 554 dams operated by the Corps of Engineers.
An Ontario Hydro study of data from several hundred North American dams
shows that on average hydrodam operating costs rise dramatically after
around 25-35 years of operation due to the increasing need for repairs.
When the cost of maintaining an old dam exceeds the receipts from power
sales, its owners must decide either to invest in rehabilitating the dam,
or, if the cost of repairs would be prohibitive, to disconnect the dam
from the grid and cease producing power.
Many old dams in the US have simply been abandoned by their owners.
According to the Michigan Department of Natural Resources (MDNR), several
abandoned small dams have been washed out during storms in recent years.
"These failures," says the MDNR, "have caused extreme
erosion, excessive sediment deposition and destruction of aquatic habitat
accompanied by the loss of the fisheries." Michigan taxpayers,
through the MDNR, have had to pay for removing several "retired"
hydroelectric projects, while their ex-owners have suffered no financial
liabilities.
Restoring the Elwha
The best-known dam decommissioning controversy surrounds a pair of dams
that decimated fisheries on the Elwha River in Washington State: the
31-meter Elwha and 70-meter Glines Canyon Dams. Built in the 1910s and
1920s with a combined installed capacity of 19 megawatts, the dams all but
wiped out the river’s once-rich runs of steelhead trout and salmon,
fisheries to which the Elwha S’Klallam Tribe had been guaranteed rights
"in perpetuity" in the remarkably aptly named 1855 Treaty of
Point No Point. Power from the two dams (now within the borders of Olympic
National Park) is devoted entirely to supplying a pulp and paper mill.
Since the Glines Canyon Dam FERC license came up for renewal in the late
1970s, the Lower Elwha S’Klallam and environmentalists have been trying to
get the dams removed. In 1992 their long campaign started to bear fruit
when Congress directed the Interior Department to detail the best plan for
"full restoration of the Elwha River ecosystem and the native
anadromous fisheries." The Interior Department concluded that only
removing the dams could fully restore the ecosystem.
- Visit International Rivers’s River
Revival project web page to learn more about subsequent
developments in the dam decommissioning movement!
Additional Information
For further information, please contact:
Day of Action Coordinator
International Rivers
1847 Berkeley Way
Berkeley, CA 94703 USA
Phone: +1 510-848-1155
Fax: +1 510-848-1008
E-mail: dayofaction [at] internationalrivers [dot] org'
