Claybanks, Mio, Michigan

The Claybanks site, located approximately 2 miles downstream of Mio in Oscoda County, MI, contributes an estimated 262 tons of sediment to the Au Sable River system, based on streambank erosion formulas.  On this stretch of river, there is natural erosion of the high sandy bluffs along the streambank. 

The erosion of the Claybanks bluff can be traced to numerous causes.  In addition to the small amount of erosion that naturally occurs on high bluffs and the outside of river bends, the erosion of this site has been exacerbated by human access issues.  It was reported that erosion rates began to increase as recreational tubers found an interesting opportunity to run up the bank, and slide back down to the river.

Erosion Rate Increases:

As the recreational traffic increased, the vegetation was damaged to the point it could no longer stabilize the sandy topsoil. The topsoil began to erode exposing the underlying clay layer. This made the 50ft bluff more slick, which invited more human traffic. At our last meeting it was reported that people were carrying their canoes up the bluff and riding in them down the bluff, back to the water. There is also a large tree at the base of the slope which is providing a jumping platform for recreational boaters. The total stream distance considered as part of this erosion problem has increased to over 1200 linear feet, nearly a quarter of a mile, with the most intense erosion occurring along a 250 ft stretch.

Addressing the Issues:

There are two factors that need to be addressed to reduce the erosion of the Claybanks site. First, further human access to the site needs to be curtailed to prevent the root cause of the soil losing stability. Secondly, since the topsoil has all been eroded and deposited in the adjacent stretch of river, there will have to be a concerted effort to add soil back to the site to nourish plantings during the stabilization project.

In October 2006, 25 whole trees were placed along the water’s edge on the Claybanks site. This part of the project, funded by the Michigan Department of Natural Resources and the US Forest Service, will serve several purposes. Most importantly, they will prevent access to the bank by recreational boaters. Secondly, the trees will act as buffers to the incoming water energy. Slowing the water along the shoreline will help decrease the erosion potential of the river’s velocity. Finally the trees will begin to replenish habitat along the bank that has been degraded by the sedimentation that follows bank erosion.

Resoration Activities:

The trees are performing well, as it is evident that sediment is beginning to accumulate behind the trees in the slower water.  Though the Large Woody Debris is functioning as expected, there is more work to be done.

There is a need to replace the topsoil that has been eroded so that when plant material is used, there is suitable substrate for them to root into. The underlying clay will make it difficult for plants to establish without the supplemental soil. To stabilize the soil in the interim until plants become established, coconut fiber logs have been placed from the water's edge to the height of the floodplain on the opposite bank.  These coir logs will provide a “soft” wall to protect the bank from high water flows and to hold back any loose sediments.  Nearly 600ft of coir logs were installed.  In addition to the logs at the toe of the slope, several logs were placed at logical breaks in slope as you head up the bank.  These logical breaks may be where a seep exits the bank, or a slump has created a small shelf or terrace.

Next, mulch fabric will go over the soil and be pinned down with landscaping staples.  Finally, native vegetation will be planted. As the plants continue to grow, the integrity of the site will increase, making the stabilization more effective with time.

Current Status:

Initial stabilization treatments have been completed.  Sixty logs, each 10ft long and made of coconut fiber, or coir, were installed over a 3 day period during the last week of August.  Over 10 cubic yards of field stone were placed at the outlet of a drainage culvert to prevent further incising activity from the flowing water.  The invert of the culvert also received attention.  Two cubic yards of material were placed and compacted over the pipe.  This will ensure that water goes into the pipe and not over, preventing erosion around the structure.

This phase of restoration on Claybanks was completed by staff from Huron Pines, US Forest Service, US Fish & Wildlife Service, and five volunteers.  Thank you to everyone who participated.

The next step is to revegetate the site.  This will be started this winter with the placement of live stakes of willow, dogwood, and balsam poplar.  These stakes will sprout and grow into small shrubs and trees as soon as the growing season starts in Spring 2008.  Also in Spring 2008, soil, seed and mulch will be placed to reestablish native grasses, followed by a thorough planting of native perennials.

Funding for this restoration has been provided by US Fish & Wildlife Service, US Forest Service, the Michigan Fly Fishing Club, and the William B. Mershon Chapter of Trout Unlimited.

Project Update:

A site inspection in November 2007 revealed positive results.  The coir logs that were placed high on the slopes are successfully reducing the down-slope erosion of sediment.  Several deposits of sediment have been observed behind the coir logs (below), proving, in the short-term, that coir logs can be used as a terracing technique on steep clay soils.  With the addition of vegetation this spring, the coir log terraces should increase in their ability to stabilize upper slopes.

For more information on the Claybanks project, please contact:

Patrick Ertel, Project Manager 
Huron Pines
(989) 348-9319 ext. 19
patrick@huronpines.org