Wednesday, March 25, 2009

A rare kind word for dams


Back when (one of the many) stimulus package was being considered by Congress, the American Society of Civil Engineers (ASCE) published a state of the country report listing $2.2 trillion dollars in needed repairs to the nation's infrastructure, including roads, bridges, dams, powerlines, and many other projects that would have kept civil engineers busy and well-payed for the foreseeable future. I found this unethical, and wrote a 4 part evisceration (1, 2, 3, 4)which elucidated my belief that this report was dubious in its publish date being during the time Congress was debating the amount of infrastructure spending to be in the stimulus package.

However, I want to revisit what I said about dam removal as an environmental boon, in light of a current event. Here, the National Weather Service site shows a bright green blob over most of North Dakota and parts of South Dakota and Minnesota. Up there, they've had up to a foot of rain, and in some parts had nearly three feet of snow, which is now melting. Flood waters are up all along major rivers like the Red River, and most of those rivers drain into the Missouri river, which heads down through South Dakota, along the border between Iowa and Nebraska, then across the state of Missouri to St. Louis where it joins the mighty Mississippi river and heads to Louisiana.

The Army Corps of Engineers has come up with a brilliant tactic to keep the Missouri river from overflowing its banks as this surge of water heads downstream. In anticipation of the increased water flow, the ACE will open the outlets on all their reservoirs downstream of the flooded area. This will increase the flow in the Missouri river, while decreasing the pool (level) in the ACE managed reservoirs. As the flood water moves downstream, the reservoir outlets are then closed, and they fill back up, while not contributing to the flow in the Missouri river. This minimizes the amount of non-flood water in the river and helps reduce flood potential. As the flood waters recede, the outlets on the rivers are opened back up, and water is released until the normal pool is achieved, at which the outlets are reduced to normal flow. In this way, they pre-pad themselves against the coming flood and reduce flood potential nationwide.

This would not be possible without dams. All of the ACE reservoirs have artificial dams and use them effectively for this purpose. Many human lives and much property is saved through the use of ACE reservoir management to prevent flooding. We all owe a debt of gratitude to these reservoirs for helping us maintain our way of life even in turbid Spring weather.

That said, I want everyone to remember that migratory fish populations is natural. Occasional flooding of rivers and streams is natural. Humans living more than 5 feet above the FEMA 100 year flood plain is natural. Artificial dams and large cities below the 5 foot FEMA level are not natural, and are just a couple bolded items in a laundry list of things that America needs to fix if we truly are committed to environmental longevity.


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