(Sorry for x-postings, this is definitely relevant for Africa)
Don't repeat our mistakes on dam building, US urges Asia
Hydropower advocates point to the US as a reason to press ahead with
controversial plans, but it is still spending time and money fixing
When confronted with criticism of proposed dams, hydropower boosters
in Asia and beyond have often pointed to the example of American
hydropower. If the US dammed their rivers, the argument goes, then why
ï¿½Look at all the hydropower in the world,ï¿½ said Viraphone Viravong, a
vice minister in Laosï¿½s Ministry of Energy and Mines, at an October
forum on that countryï¿½s controversial dam plans. ï¿½If [these dams] are
so bad, why donï¿½t you decommission all of them?ï¿½
In an attack on opponents of Chinese dam plans in the countryï¿½s water-
rich south west in May, Zhang Boting, deputy secretary general of the
China Society for Hydropower Engineering, also pointed to the US to
show that dam cascades were common practice, stating (incorrectly)
that the Tennessee River alone has 70 hydroelectric dams.
The US has learned quite a lot during a century of dam building. While
many projects have yielded valuable energy, flood control and
irrigation benefits, hydropower advocates abroad often fail to note
how much money and effort the US has spent undoing the damage of
poorly conceived dams.
The US demolished its 1,000th dam in 2011, with 430 removed just in
the last decade. Removing dams is expensive ï¿½ sometimes astonishingly
so ï¿½ but government and environmental leaders alike say that some dams
prove simply too harmful to keep.
To countries just beginning to experiment with large-scale hydropower,
US scientists, environmentalists and government officials all caution:
donï¿½t make the same errors we did.
"We've learned some hard lessons about what happens when you make
certain infrastructure decisions,ï¿½ US secretary of state Hillary
Clinton told a gathering of Mekong region leaders in July. ï¿½Iï¿½ll be
honest with you, we made mistakes.ï¿½
History of US dam-building
After China, the US is the most dammed nation on earth. There are
about 79,000 dams in the US Army Corps of Engineersï¿½ national
inventory, as well as many smaller projects that donï¿½t meet the Corpsï¿½
minimum size requirements for listing. Some 2,500 dams produce
The twentieth century was a golden era of dam building in the United
States. ï¿½Every stream should be used to the utmost,ï¿½ wrote then-
president Theodore Roosevelt in 1908, and within decades the US
embarked on a dam-building binge that placed barriers on virtually all
of the countryï¿½s main rivers.
This era gave birth to the countryï¿½s two most valuable sources of
hydropower: Hoover Dam, completed on the Colorado River in 1936, and
the Columbia Riverï¿½s Grand Coulee Dam, finished in 1942. The dams
remain the countryï¿½s largest hydropower producers (proof, many critics
of new dams contend, that the best sites were taken long ago.)
Starting in 1960s, however, dam building ran out of steam. A raft of
federal legislation, such as the Wild and Scenic River Act of 1968 and
the National Environmental Policy Act of 1969, forced developers to
take riversï¿½ ecological benefits into account before plowing ahead
The US government also had to contend with a public less tolerant of
damsï¿½ high construction costs and increasingly concerned with
ï¿½We went on this dam building binge in the early mid 1900s, and then
we realised, ï¿½Wow, weï¿½ve dammed most of our best rivers and that comes
with serious costs,ï¿½ï¿½ said Amy Kober, spokeswoman for the
environmental group American Rivers.
The trouble with dams
Dams, by definition, turn rivers into reservoirs. This has profound
Changes in sediment patterns can have consequences thousands of miles
in either direction of a dam. A few degreesï¿½ temperature change can
destroy whole ecosystems. Blocked fish migration can be disastrous for
the species themselves and the humans who depend on them for sustenance.
A legend among some Native American tribes in the Pacific Northwest
holds that the Elwha Riverï¿½s salmon were once so plentiful a man could
cross the river by walking on the fishesï¿½ backs. The river has lost
some 90% of its salmon since it was dammed in the early twentieth
In addition, as imposing as a concrete behemoth like Hoover Dam may
seem, dams in fact have a limited lifespan. Maintaining them can be
staggeringly expensive ï¿½ and as decades pass, it can be increasingly
hard to identify the federal, state or local entity responsible for
ï¿½Weï¿½ve ended up with a lot of dams that arenï¿½t serving economic needs
anymore but nobodyï¿½s really responsible for them,ï¿½ said Jane C. Marks,
a professor at Northern Arizona University who helped rehabilitate
Arizonaï¿½s once-dammed Fossil Creek. ï¿½There are rivers that are damaged
for really no good reason.ï¿½
If the last century was a golden age of dam building, the early part
of the twenty-first century has been a golden age of dam dismantling.
ï¿½There is a willingness in this countryï¿½ to reevaluate some of the
benefits versus the costs of some facilities,ï¿½ said commissioner
Michael Connor of the US Bureau of Reclamation, which oversees water
management in the US and built many of the last centuryï¿½s dams.
The current trend toward dam removal began with the Edwards Dam on the
Kennebec River in the northeastern state of Maine. Built in 1837 for
hydropower and navigation, the dam ruined fish stocks and transformed
the once-lush region into a symbol of industrial decay. The mills
along the river eventually closed, rendering its small amount of
hydropower generation obsolete.
When the damï¿½s federal license came up for renewal in 1993, a
coalition of environmental groups, state and federal agencies lobbied
hard for the damï¿½s removal. After a decade of intense legal wrangling,
the dam was taken down in 1999 and the river successfully rehabilitated.
In September 2011, the US launched its most ambitious dam demolition
to date ï¿½ the US$325 million (2 billion yuan) removal of the Elwha
River and Glines Canyon dams, the dams that decimated the once-
abundant salmon of the Olympic Peninsula.
An era of smarter dams?
No one is suggesting that all US dams should be removed. Hydropower is
the second-largest source of renewable energy in the US after biomass.
Instead of looking for new sites to build dams, the Bureau of
Reclamation is looking for ways to extract more hydropower from
existing facilities, Connor said.
Modern technology also enables engineers to build smarter dams than
their twentieth-century predecessors ï¿½ and to be more prudent in
choosing whether to build in the first place.
ï¿½Countries that are considering new dams for hydropower generation
should make careful consideration of the damage that can and will be
inflicted upon the environment and livelihoods of many people,ï¿½ said
Rupak Thapaliya of the conservation-minded Hydropower Reform
Coalition. ï¿½While the intentions of many governments may be good, the
actions may not always be based on sound science and that is very
The architects of last centuryï¿½s dams worked in an era when mankind
was fully confident of its dominion over nature. Today, science is
making a very different case ï¿½ one planners should take to heart.
ï¿½The lesson for China and Brazil is just: learn from what weï¿½ve done,ï¿½
said Marks of Northern Arizona University. ï¿½Youï¿½re developing in a
different context ï¿½ in a world where weï¿½ve realised that resources are
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