17% of America's river miles are currently dammed. (Echeverria
et al., Rivers At Risk: A Concerned Citizen's Guide to Hydropower, 1989)
In a March 1989 National Park Service memo, NPS states
that "only 160 watersheds have been identified as free-flowing and
essentially undeveloped from headwaters to mouth."
Only one large river (longer than 600 miles), the Yellowstone,
is not severely altered by dams.
EPA estimates that there are 68,000 dams. National Park
Service estimates that there are 75,000 dams. Wall Street Journal estimates
that there are 80,000 dams. (Echeverria et al., Rivers At Risk: A Concerned
Citizen's Guide to Hydropower, 1989)
750 have been built by the Army Corps of Engineers and
Bureau of Reclamation. (Echeverria et al., Rivers At Risk: A Concerned
Citizen's Guide to Hydropower, 1989)
Of the 600 miles of the Columbia between the dam nearest
the ocean and the Canadian border, only forty-seven miles have not been
transformed by dams from healthy river ecosystems to impoverished reservoirs.
(R. Devine, "The Trouble With Dams," Atlantic Monthly, Aug. 1995)
According to Arthur Walz, the chief of the Army Corps
of Engineers' Geotechnical and Materials Branch, slightly more than 100,000
dams regulate American rivers and creeks. (R. Devine, "The Trouble
With Dams," Atlantic Monthly, Aug. 1995)
According to Arthur Walz, the chief of the Army Corps
of Engineers' Geotechnical and Materials Branch, some 5,500 dams are more
than fifty feet high. (R. Devine, "The Trouble With Dams," Atlantic
Monthly, Aug. 1995)
According to Arthur Walz, Chief of the Army Corps of
Engineers' Geotechnical and Materials Branch, reservoirs nationwide have
inundated an area equivalent to New Hampshire and Vermont combined. (R.
Devine, "The Trouble With Dams," Atlantic Monthly, Aug. 1995)
43 million gallons of water are used to pass one ship
in a single lock on the Snake River. This much water could provide enough
energy for an average home for an entire year (roughly $700 worth). (R.
Devine, "The Trouble With Dams," Atlantic Monthly, Aug. 1995)
Rendering the Columbia and the Snake rivers navigable
for barges costs tens of millions of dollars a year in direct and indirect
subsidies. (R. Devine, "The Trouble With Dams," Atlantic Monthly,
Aug. 1995)
Releases from Glen Canyon Dam render the Colorado River
too cold - some 20 degrees colder than is natural - for most native organisms
for more than 250 miles downstream, resulting in an effectively dead river.
(R. Devine, "The Trouble With Dams," Atlantic Monthly, Aug. 1995)
Glen Canyon Dam captures 99.5 percent of the sediment
tumbling down the Colorado. (R. Devine, "The Trouble With Dams,"
Atlantic Monthly, Aug. 1995)
According to the US Geological Survey, the amount of
reservoir capacity created by each cubic foot of dam fell from 10.4 acre
feet for dams built prior to 1930 to 2.1 acre feet for those built in the
1930's and to 0.29 acre feet for those built in the 1960's. (R. Devine,
"The Trouble With Dams," Atlantic Monthly, Aug. 1995)