While removal of the Grayling Mill Pond Dam was initially a controversial option, the results have yielded a positive outcome. Restoring the riverchannel with naturalized rapids has provided environmental, recreational, and sustainability benefits.
Removing the steel weir structure and restoring the Au Sable River to a more natural state has helped fish populations (particularly trout) to migrate upriver. Networks of boulders were used to reinforce the stream channel and to control the erosive force of water, protecting both the stream channel and the nearby I-75 Business Loop bridge from long-term erosion and scour.
The naturalized channel has lowered the original impoundment in Mill Pond by one foot, eliminating the “thermal pools” that threatened trout species. The naturalized channel has also significantly enhanced the aesthetics of the adjacent City Park, providing a view that is more attractive than the original steel structure.
This project has enhanced the trout fishery throughout the entire Au Sable River watershed and upriver. While this is important from an ecological perspective, the availability of recreational fishing opportunities is indispensable to the economic health of Michigan communities like Grayling. Providing flourishing recreational opportunities attracts tourists and sports enthusiasts, which benefits the City and the entire region. The naturalized channel improves aesthetics and provides other recreational opportunities, such as canoeing, rafting and kayaking.
A less visible benefit of this project was derived from the improved sustainability of infrastructure at this site. The elimination of the steel structure drastically reduces maintenance costs that are associated with addressing structure corrosion and joint failures. Emergency measures required in the past, such as protecting the structure, downstream channel, and adjacent bridge during high flows, are less likely to be needed.
Naturalizing the channel also removed the impoundment’s status as a dam. This allowed the City of Grayling and MDOT to avoid reluctant ownership of a dam, while also removing the site from MDEQ regulation as a dam. This is a very attractive benefit that eliminated the costs associated with the required biannual safety inspections and reports.