Stream Restoration
JB: This is Earth and Sky. It’s natural for soil to erode along streams and rivers.
DB: But cutting down trees, building roads, grazing cattle and filling in wetlands all contribute to streambank erosion. Sometimes valuable land is lost, and water quality deteriorates.
JB: Consider Tenmile Creek near Helena, Montana. Back in the late 1800s, miners re-routed stretches of the creek to build a small-gage railroad that would carry ore from mountaintop mines. Afterwards, the creek ran straighter and faster. Streambank erosion sped up. The silt and sediment ruined fish habitat.
DB: Fast-forward to 1998, when the U.S. put in place a new “Clean Water Action Plan.” It called for partnerships between federal and state agencies and local groups. The Montana Department of Natural Resources joined with the U.S. Forest Service and others. Crews from the Montana Conservation Corps worked side by side with volunteers from Helena. The result was thousands of native trees and plants along Tenmile creek. Today, cottonwoods, sandbar willows, dogwood, and silver buffaloberry cover streambanks that used to be bare and crumbling.
JB: Meanwhile, across the U.S., there are hundreds of other streambank restoration projects. Most rely on community action to be effective. For more on some of these projects – come to today’s show at earthsky.com. We’re Block and Byrd for Earth and Sky.
Our thanks to the following individual who assisted in the preparation of this script:
Steve Nelsen
Executive Director
Montana Conservation Corps
Bozeman, MT
Jesse Aber
Water Resources Planner
Montana Department of Natural Resources and Conservation
Helena, MT
Gordon Grant
Research Hydrologist
Pacific Northwest Research Station
USDA Forest Service
Gordon Reeves
Research Fisheries Biologist
Pacific Northwest Research Station
USDA Forest Service
Tom Spies
Scientist
Experimental Forest
Pacific Northwest Research Station
USDA Forest Service
For more info:
This website lists the streambank restoration projects that were carried out in 1999, 2000 and earlier through funding provided by “Five-Star Restoration Challenge Grants,” which are a joint effort of the National Fish and Wildlife foundation and the U.S. EPA. These grants provide support for “community-based wetland and riparian restoration projects.”
North Carolina State University website on best-management- practices for riparian restoration
U.S. Forest Service web site with links to info on riparian management
Info on riprap as a means of preventing streambank erosion (Ohio State University)
EPA website on the benefits of revegetation for streambank restoration
Sottir, Robbin. “Brushing up on erosion control.” American City and Country, February 1998.
Barrett, K.B. “Ecological Engineering in Water Resources: The Benefits of Collaborating with Nature. Water International 24 (3): 182-188; 1999.
Author’s notes:
A traditional approach to the control of streambank erosion is to “armor” the streambank with materials that are resistant to erosion-for example, “riprap” (layers of stone) or gabions (wire boxes filled with smaller stones). Increasingly, however, environmental engineers turn to a more natural solution, soil bioengineering. This approach can be both effective, aesthetically appealing, and low in cost.
“Soil bioengineering” is a general term that encompasses a variety of strategies for holding streambanks in place. The key is the use of living plants to retain soil. At the same time, the plants slow down and filter runoff, to reduce pollution; and they reduce the velocity of the streamflow, which reduces the potential for erosion. Natural plantings along streambanks also shade the stream, improving fish habitat, and provide food and cover for the animal species that live near streams.
Here are some examples of soil bioengineering techniques that reduce streambank erosion (there are many others; and many of these are used in combination with rip-rapping and other traditional streambank engineering techniques):
Blanketing (also called “Mattressing”): The bare streambanks are covered with a “blanket” of live tree cuttings held in place with wire mesh or geotextiles. The blanket immediately reduces sediment loading from runoff and the cuttings root quickly.
Live cribwall: box-like structures built of logs (cribs) are filled with soil. Live branch cuttings placed in the cribs take root and will eventually take over from the crib structure in stabilizing the streambank.
Live fascines: Long bundles of branch cuttings from willows or cottonwoods are bound in rows and placed in shallow trenches along the slope of the riverbank.
Tree revetment: Live trees are uprooted and laid on their sides at the base of the streambank with their tops pointing downstream. Eastern red cedar, which resists decay when wet, is a good species to use. The tree branches reduce the velocity of the streamflow, so that sediment is deposited on rather than removed from the streambanks.
Additional Teacher Resources
U.S. National Park Service: What is Watershed Restoration? And Why Should We Care?
Watershed restoration is an attempt to bring the land back into a natural state after it has been altered. While it focuses on water absorption, drainage, and erosion; it also takes into account all water related issues associated with a drainage area. This site explains how streambank as well as other forms of erosion affect us all.
U.S. Fish & Wildlife Service, North Carolina Wildlife Resource Commission, Stream Notes: Streambank Erosion
Stream stability is an active process, and while streambank erosion is a natural part of this process, we have often accelerated this erosion by altering the stream system. This site report explains how we alter and accelerate the erosion process.
U.S. Geological Survey, Watershed Success Stories: The Boulder and Upper Tenmile Creek Watersheds?Cleaning Up a Century of Hardrock Mining
A brief history of the environmental damage done to the Boulder and Upper Tenmile Creek watersheds, as a result of years of mining. Also covered is the subsequent recovery efforts undertaken and the success achieved thus far.
