When most people in Northeast Ohio think of winter, planting things outside usually isn’t the first thing that comes to mind. But if you are a landowner dealing with eroding streambanks, it should! November through March is the ideal time to install live stakes, live fascines, brush mattresses, or a combination thereof. Collectively known as streambank bioengineering or vegetative streambank stabilization practices, these relatively inexpensive solutions for minor-moderate streambank erosion benefit from installation during their winter dormancy.
In order to address streambank erosion, landowners typically utilize "hard engineering" solutions such as concrete walls, rip-rap or gabion baskets. While these approaches usually succeed to halt streambank erosion at the site, they tend to deflect the stream's energy downstream, essentially moving the erosion problem to another location. They also create poor habitat conditions for aquatic life, including fish, amphibians and aquatic insects.
In contrast, bio-engineering techniques utilize natural woody vegetation to stabilize eroding streambanks. The roots anchor the soil in place as they develop, and the stems and leaves protect the streambank soil from the energy of flowing water, while actively reducing the near-bank stream velocity and enhancing in-stream and streamside habitat.
Live stakes are dormant, live woody cuttings of a species with the branches trimmed off. Live staking performs an important function in creating a root mat that stabilizes the soil by reinforcing and binding soil particles together. Stake establishment also provides habitat for wildlife. Dormant stakes/live cuttings of willow stakes or a mix of willow and red-osier/silky dogwood stakes should be installed on any area of bare soil along the streambank in areas of full sun to part shade. In shady areas, ninebark and elderberry live stakes will serve better. Pilot holes at least half the length of the stake or post should be created using similar diameter rebar. Posts and stakes can be installed as densely as one per square foot of exposed streambank.
Live fascines are long bundles of live woody vegetation (usually willows, sycamores and/or red-osier dogwood, but also including ninebark or elderberry in shady areas) that are installed parallel to the stream flow along the toe of a streambank. When placed in shallow trenches at the toe and across the slope of a streambank, these 6-10 inch diameter bundles provide protection from erosion and create a sediment trap. This material provides immediate bank support even prior to root growth. Once established, this living root material grows into a living fence-like erosion barrier. Within one growing season, roots and shoots grow along the entire length of the structure, quickly stabilizing the bank.
Brush mattresses are layers of living branches laid in a crossing pattern, 1-2 branches thick, on a streambank to form a living ground cover. The mattress that is formed protects the bank surface until the branches can root and native vegetation becomes established. This living system normally roots in the entire bank face. They are anchored to the slope using stakes and biodegradable twine. Brush mattresses should only be installed on streambanks with a slope of 1:1 or shallower, and often complement streambank grading activities. As with other bioengineering practices, typical species for brush mattresses include willows, red-osier dogwood and sycamore, or ninebark and elderberry in shadier areas.
We invite anyone interested in learning how to install live stakes and live fascines to attend our Volunteer Vegetative Streambank Stabilization event at the Strongsville Backyard Preserve on March 30, 2019. Both a morning session and an afternoon session are available.
Blog author: Jared Bartley, Rocky River Watershed Program Manager