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 past
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
"Look at all the hydropower in the world," said Viraphone Viravong, a
vice minister in Laos's Ministry of Energy and Mines, at an October
forum on that country's controversial dam plans. "If [these dams] are so
bad, why don't you decommission all of them?"
In an attack on opponents of Chinese dam plans in the country's
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 – sometimes astonishingly so –
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:
don't make the same errors we did.
"We've learned some hard lessons about what happens when you make
certain infrastructure decisions," US secretary of state Hillary Clinton
told a gathering of Mekong region leaders in July. "I'll be honest with
you, we made mistakes."
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 Engineers' national inventory, as
well as many smaller projects that don't meet the Corps' minimum size
requirements for listing. Some 2,500 dams produce hydropower.
The twentieth century was a golden era of dam building in the United
States. "Every stream should be used to the utmost," 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 country's main rivers.
This era gave birth to the country's two most valuable sources of
hydropower: Hoover Dam, completed on the Colorado River in 1936, and the
Columbia River's Grand Coulee Dam, finished in 1942. The dams remain the
country's 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
rivers' ecological benefits into account before plowing ahead with
The US government also had to contend with a public less tolerant of
dams' high construction costs and increasingly concerned with
"We went on this dam building binge in the early mid 1900s, and then we
realised, 'Wow, we've dammed most of our best rivers and that comes with
serious costs,'" said Amy Kober, spokeswoman for the environmental group
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 degrees' 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 River's salmon were once so plentiful a man could
cross the river by walking on the fishes' backs. The river has lost some
90% of its salmon since it was dammed in the early twentieth century.
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 – and as decades pass, it can be increasingly
hard to identify the federal, state or local entity responsible for its
"We've ended up with a lot of dams that aren't serving economic needs
anymore but nobody's really responsible for them," said Jane C. Marks, a
professor at Northern Arizona University who helped rehabilitate
Arizona's once-dammed Fossil Creek. "There are rivers that are damaged
for really no good reason."
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.
"There is a willingness in this country… to reevaluate some of the
benefits versus the costs of some facilities," said commissioner Michael
Connor of the US Bureau of Reclamation, which oversees water management
in the US and built many of the last century's 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
When the dam's federal license came up for renewal in 1993, a coalition
of environmental groups, state and federal agencies lobbied hard for the
dam's 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 – 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 – and to be more prudent in
choosing whether to build in the first place.
"Countries 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," said
Rupak Thapaliya of the conservation-minded Hydropower Reform Coalition.
"While the intentions of many governments may be good, the actions may
not always be based on sound science and that is very important."
The architects of last century's dams worked in an era when mankind was
fully confident of its dominion over nature. Today, science is making a
very different case – one planners should take to heart.
"The lesson for China and Brazil is just: learn from what we've done,"
said Marks of Northern Arizona University. "You're developing in a
different context – in a world where we've realised that resources are
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