&gt; The write-up is a bit vague and misses one major point: not all of these dams in the U.S. are concrete<p>The write-up is in response to a question asking how long dams like the Hoover Dam, which is a large concrete dam, are designed to last. It wasn&#x27;t suggesting that all dams are concrete.<p>The single sentence: &quot;Indefinitely with regular maintenance&quot; is a rather short article length, so Straight Dope decided to educate their readers that the large dams, which make great action-packed movies when they fail catastrophically, are the very least of our worries since earthen or other natural material based man-made dams, which generally have significantly less water capacity, are in fact at more risk of failure and potentially even more damage (like the cascading failures in SC this past year, or the Banqiao Dam incident).