Erosion Assessment Training
Recently a group of ANBAF volunteers met with John Bailey of Huron Pines, to learn to identify, classify, measure, and prioritize erosion sites on our North Branch.
Excessive sediment was identified as the major concern in our North Branch Au Sable River Watershed Action Plan, 2009. Severe erosion is certainly a problem for river side property owners, but it also is harmful to the River. The sediment added to the river adversely impacts the insects and fish directly and indirectly affects the wildlife that depend on the insects and fish for food. Some erosion is caused by the manner in which property owners develop and manage their riverfront and some erosion is the result of natural forces, although perhaps accelerated by human control of the river, such as clearing trees that block river passage.
Our initial training began with a classroom-like session on identifying sites and using Huron Pines’ “Streambank Erosion Severity Index” form. Then it was off to the river for hands-on learning by doing.
We did three sites in the Red Dog area. The lower river offered the sort of obvious erosion that even we beginners could spot. It was seeing an erosion site there, bleeding sand into the River during a rain storm, which led me to the notion that something should be done to reduce the adverse impacts on our river.
Two of the sites were quite near one another, but much different in character. Everyone participated in measuring height, length, slope ratio and river width and depth. We rated soil composition, vegetation coverage and likely causes of the erosion. John Bailey even detailed the remediation techniques he would recommend for each of the different sites. The final step was to score all this information to determine the erosion severity of each site. Two rated severe, the other was just two points shy of that rating.
Afterwards we met to discuss next steps. First, in October we will do more initial assessments, likely working in at least two teams, covering Kellogg Bridge to the confluence. Our plan is to record GPS coordinates of these erosion sites, photograph them and complete a Severity Index form for each. We will re-assess these sites each year about this same time, until we are able to raise the necessary funds and work with property owners to do remediations. Also this winter, we will check in on these initial sites to determine the impacts of ice and high water flow. We will also begin identifying erosion sites in other reaches of the North Branch and Big Creek for future assessment.
All of this work is the necessary research for determining and prioritizing what the ANBAF can and will do to reduce the excess sediment harming our river.
We also learned there are steps property owners can take to prevent or reduce that type of erosion caused or exacerbated by the manner of property development or use.
One recommendation is to discontinue mowing along a 6-8 foot wide strip of the bluff closest to the river, to create a “buffer zone”. This will allow rainwater to soak into the soil and prevent runoff washing down the bluff. Then it will further help to plant a mixture of wildflowers in the buffer zone, for example the Pollinator Seed Mix Packet available online at www.michiganwildflower.com. There are other grasses and bushes that will also have the root structure to help stabilize and hold the bank.
Thanks to our volunteers: Tom Wessels, Mike Inman, Bill Anderson and Terry Lyons