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--></style><title>At 50+ years old, many US dams become
hazards</title></head><body>
<div><font face="Lucida Grande"><b>Excerpt: </b> Dam removal
projects that will provide significant ecological benefits, such as
the Nelson, are of the highest priority, says Scott. Another
requirement is that the structure be a "deadbeat dam"-one
that has outlived its useful life and has now become a
hazard.</font></div>
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More than 14,000 such dams exist around the country already. By 2020,
more than 70 percent of the U.S.'s dams will be more than 50 years
old, with many of those soon becoming candidates for removal. It's a
growing movement, with dozens of dams coming down every year. The main
obstacle is the often high price tag of removal, which can run tens of
millions of dollars. Yet maintaining old dams and retrofitting them to
meet newer standards also comes at a cost.</font></div>
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<div
>http://news.nationalgeographic.com/2016/11/dam-removal-nelson-dam-ma<span
></span>tiliha-rogue-river-hewlett-foundation-open-rivers</div>
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" 'Triage' is a dirty word in some conservation circles, but like
many dirty words, it describes something common. Whether they admit it
or not, conservationists have long had to make decisions about what to
save.<br>
<br>
"As more and more admit it, open discussion about how the
decisions are best made - by concentrating on particular species, or
particular places, or absolute costs, or any other criterion - becomes
possible. Whichever criteria come into play, one thing remains
constant. The decisions have to be made quickly."<br>
<br>
Emma Marris, "What To Let Go."<br>
<i>NATURE</i> November 8, 2007</font></div>
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" Š organisms have a physiological response to temperature,
and these responses have important consequences Š. biological rates
and times (e.g. metabolic rate, growth, reproduction, mortality and
activity) vary with temperature."</font><br>
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<div><font face="Lucida Grande" size="-1" color="#000000">Anthony I.
Dell, Samraat Pawar and Van M. Savage, Temperature dependence of
trophic interactions are driven by asymmetry of species responses and
foraging strategy <i> Journal of Animal Ecology</i>
2013<x-tab> </x-tab><br>
doi: 10.1111/1365-2656.12081</font></div>
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<div><font face="Bookman Old Style" size="-1"
color="#000000">"Whereas any one line of evidence may be weak in
itself, a number of lines of evidence, taken together and found to be
consistent, reinforce one another exponentially."<br>
<br>
Preston Cloud and Aharon Gibor. The Oxygen Cycle. <br>
<i>Scientific American</i>, September 1970</font></div>
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