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Nov 15 2011

“Natural Dams”

Dam removals have been a “BIG” item in the news lately.  This is true in both the size and number that are happening, and the fact that the largest, and second largest, dam removals in U.S. history are currently underway.  In case this is news to you, here are a few of the larger removals in the works:

 

 

 

More info about the Elwha Dam and Glines Canyon Dam can be found at the NPS Dam Removal Blog.  There are also live web cams showing the progress of their actual removal.

While it is a good thing to remove an old, outdated, and inefficient dam, not all dams need to, or should, come out.  John Seebach from American Rivers says it well;

“But it’s also worth taking a moment to remember that most dams aren’t going anywhere, and with good reason. If we woke up tomorrow to discover that every dam in the world had vanished overnight, our rivers would be much better off. But we’ve grown to depend on many dams to help us light our houses, irrigate our crops, and supply our cities with water. Make no mistake: these dams are still hurting rivers. But since we need them, the responsible thing to do is to find ways to make them cause as little harm as possible.”

A lot of dams in the U.S. are not large, towering, concrete walls, and in fact, most are considered small (less than 15ft high!).  While several small dams have been removed recently as well, there are still many that will stay and are in need of repair and rehabilitation.  There are also new small dams being constructed in the U.S. 

Why not replace these dams, or build new ones, with a more “natural dam” that still controls the grade and water surface of the stream, but mimics similar natural riffles that already occur in streams?  A structure that looks more natural and allows for fish passage, boat navigation if applicable, and continuity of habitat.

Coming up next I will walk through a few examples of these, including:

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