A few thoughts from Neil Gillies, Director of CI.  Few among us have a realistic image of the eastern-American landscape 200-300 years ago.  Most picture a landscape of nearly continuous forests bisected by free flowing streams.  The reality was very different.  At a time when beavers were found in great abundance throughout the country, nature’s engineers dammed most small streams.  The fur trade nearly eliminated beavers in the East by the late 19^th century and they now only occur in many areas because they were reestablished by State and Federal wildlife agencies. 

When asked what they think about beavers, many – if not most-- people immediately focus on the negatives: they kill our favorite trees; they put dams where we don’t want them; they keep fish from moving freely through our streams; they flood our fields, our roads; they…etc.  Even people like me who value the landscapes created by beavers and enjoy the creatures themselves are equally aware of the negatives. 

I attended a talk several years ago that forced me to reconsider the beaver “equation.”  The speaker was describing changes to the land during the period of historical record in the lower Chesapeake drainage area.  One comment in particular stuck with me: as beavers were trapped out, many perennial streams became intermittent and then stopped flowing altogether--indicative of a dropping water table.  Current research in the American West affirms that the return of beavers provides “appreciably greater and longer summer flows and elevated groundwater levels… Some ephemeral streams have started to flow throughout the year.”   An excellent overview of the water quantity and riparian habitat benefits provided by beavers is available from the Colorado Riparian Association at http://webspinners.com/riparian/GreenLine/V09-2/BeaverDam.html.

I’ve been thinking a great deal about this recently.  As our small streams dry up nearly every summer, I wonder if it has to be that way.  I believe concerns about groundwater recharge should lead us to reconsider the very positive benefits that beavers provide to the landscape or, at least, consider engineered "solutions" that provide the water storage/groundwater recharge benefits of beaver dams without the negatives of beavers themselves.  In Wyoming they have developed low-cost methods to construct beaver dam-like structures for about $11.00 per acre-foot of storage-- about 1/100^th the cost of traditional reservoir storage facilities.  

I would like to hear your thoughts on this issue.  You can contact me at the email address below.

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