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Info #2 from John Alderman

Ok, folks, I just finished walking the trails along Pokeberry Creek in Briar Chapel.  It's definitely not a pretty sight.  There is a series of old beaver impoundments and newer, mostly upstream, beaver impoundments.  The old beaver impoundments are largely gone now.  In their place is a MAJOR stream incision forming, which will transfer many tons of sediment downstream for years to come.  Basically, Pokeberry Creek will meander across its floodplain for decades digging and washing out accumulated sediment from the valley floor.  Ifrastructure, such as pipes and bridges (i.e., multiple pipes and walking bridge downstream from the large powerline cut), are significantly jeopardized.  Why the beavers largely left these downstream areas is a guess.  Were they trapped out?  Was flow during spate events so elevated that they could not maintain dams in the waterway and floodplain?  If the flows have been enhanced, what could have caused a significant increase in peak flows during spate events?  Ummm, I can guess . . . look at major changes in the surrounding landscape.  Now that the large trees and their associated roots have essentially been eliminated from the downstream valley flat in the old impounded areas, nothing other than a major, costly engineering endeavor can arrest the MAJOR Pokeberry Creek incision.  So, do you hire an engineering and construction firm to arrest and correct the incision problems along Pokeberry Creek, or do you find a way to live with the limited cost beaver engineers and encourage them to reoccupy the largely vacated downstream areas in and along Pokeberry Creek?  Remember, you essentially don't get incision in a beaver impoundment.  It could be that the beavers can't reoccupy this area due to major changes in Pokeberry Creeks hydrograph.  We will never know unless we make the effort to live with these beavers.  Part of living with these beavers is maintaining a natural hydrograph.  This will become increasingly impossible as more and more of our landscape becomes developed.  Is it possible that this is a serious warning to all of developing Chatham County?  John Alderman

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