Restoring Streams of the Past Posted on December 5, 2014 by UPLLC

One of the biggest and perhaps most overlooked changes to the landscape of North Carolina and much of the eastern US has been mass erosion of hillside soil over the last few hundred years.

Widespread land clearing for farming and logging caused this erosion and filled stream and river valleys with as much as 5-15 feet of eroded soil. Where streams once were shallow, clear, and meandering through floodplains and wetlands, they have since come to perch on top of, and then eventually erode through, layers and layers of so-called “legacy sediment.”

As a result, many streams are now trapped in steep, narrow, eroding channels, and largely disconnected from their floodplains. In other words, the character of our streams has drastically changed over the last few hundred years.

Eroded stream that has cut through 8 feet of “legacy sediment” accumulated over 100+ years.

Eroded stream that has cut through 8 feet of “legacy sediment” accumulated over 100+ years.

Restored channel using traditional stream restoration design. Note stable channel and banks. Photo credit: NC EEP

Restored channel using traditional stream restoration design. Note stable channel and banks.
Photo credit: NC EEP


Fish and wildlife have not been able to keep up with these changes. They have evolved over thousands of years to take advantage of slower-moving, relatively shallow, clear streams and stream-wetland environments. Now many species – such as freshwater mussels – struggle to adapt to the new, muddier, unstable streams of today.

One solution is to actively restore streams and their floodplains. A primary goal of stream restoration is to reduce bank erosion, but this can lead to an artificially stable, engineered channel that fails to mimic the more diverse stream habitats of the past.

Practitioners today are giving more consideration to restoring “ecological function,” and how streams used to look and behave before our valleys filled up with eroded hillside sediment. While we cannot re-create the past and have to work with modern constraints, we still want to consider restoring multiple functions: reconnecting streams with their floodplains, re-creating more complex stream-wetland systems where appropriate, and restoring diverse habitat that often looks, well, messy (but fish, salamanders, bugs and other critters love it).

Restored stream-wetland complex using valley restoration approach. Note more natural (and messier!) habitat. A diversity of aquatic species will live here. Photo credit: Art Parola, University of Louisville

Restored stream-wetland complex using valley restoration approach. Note more natural (and messier!) habitat. A diversity of aquatic species will live here.
Photo credit: Art Parola, University of Louisville


 

In some cases, beaver are even being employed as natural, native “ecosystem engineers” to help restore streams and wetlands to be more like they were in the past.

Stream-wetland complex created by beaver – a fish haven. Photo credit: NC DENR

Stream-wetland complex created by beaver – a fish haven.
Photo credit: NC DENR

Unique Places is excited to be working on several high quality stream and wetland restoration projects across the state. Have a candidate project? Let us know!

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