Reconnecting the Au Sable Watershed at the Grayling Hatchery

by Kristin Thomas, Michigan TU Aquatic Ecologist

Much has been written about the old fish hatchery in the City of Grayling, Michigan. This writing isn’t about any of that. Instead, the focus is on an aspect that has not been covered much and has everything to do with the future, not the past.

The hatchery is located on the East Branch Au Sable River, less than a half-mile upstream from where it joins the mainstem of the Au Sable. Upstream of the hatchery, the East Branch contains about 23 miles of river. The site of the hatchery has changed dramatically over the last hundred years, having experienced several different periods of manipulations to the site and the waters of the East Branch.

In its current configuration, water can leave the river and enter the hatchery water inlet immediately downstream of North Downriver Road. In another 40 yards, a dam structure elevates the water upstream at the hatchery inlet. This dam is approximately 2.5 feet in height and incidentally blocks fish passage between the East Branch and the mainstem. Downstream of the dam, the East Branch flows are forced through a narrow channel that used to be an old raceway. Within that channel, several old concrete abutments and structures no longer serve any purpose that constricts the flow further and result in velocity barriers to fish at different times.

Crawford County owns the hatchery and leases it to Anglers of the Au Sable. An affiliated but independent non-profit organization, Grayling Hatchery Inc., currently runs the dayto-day operations at the hatchery. The Grayling community greatly values the hatchery as a place for families to learn and enjoy trout, nature, and fishing. The county and community want to retain the hatchery as it is a valued part of the community.

Anglers of the Au Sable and Michigan Trout Unlimited began working together several years ago to assess whether there was a feasible and effective means to allow fish passage past the hatchery site in a manner that would maintain current hatchery operations. Preliminary surveying and assessment by the partners identified a general approach to accomplish both goals. This preliminary but feasible approach was presented to the Crawford County Board of Commissioners last year. Anglers of the Au Sable and Michigan TU asked for the commission’s blessing to apply for grant funding to conduct a complete engineering and design assessment for the project, which the county granted. Funding for the engineering and design project was awarded by the Michigan DNR Fisheries Habitat Grant program, which had the site listed as a grant-priority project.

Throughout 2022, the project partners contracted the services of Spicer Engineering and Streamside Ecological Services to help the project team accomplish full site surveying, evaluate numerous alternatives, and develop a complete design for the best option.

The hatchery site has many constraints and considerations beyond maintaining hatchery operations. The current dam has about 2.5 feet of vertical drop blocking fish passage. The dam also provides vehicle

passage to the west side of the property. A historic building is on the west side of the property, and vehicle access must be maintained. In the past, there were many more raceways than currently. The raceways were abandoned as they filled with sediment, but the concrete was not removed.

There are four additional narrow crossings downstream of the dam as the East Branch flows through the property. They constrict flow and create velocity barriers. However, at least one footbridge must be maintained to keep the circular walking path around the property. Also, some contaminated sediment is on the west side of the river downstream of the dam.

What do all of these constraints mean for project design? Well, there is little use in designing a project that can’t be built. Therefore, construction constraints needed to be considered. Concrete from old raceways makes excavation difficult and expensive in some areas. The current bridges can be removed, but at least one needs to be replaced. No one wants to disturb contaminated sediment, so digging on the west side of the river downstream of the dam needs to be avoided. In addition to these site constraints, there are a lot of stakeholders with varied interests in the hatchery, thus creating a project with complexity that extends far beyond the question of fish passage. The project team made a great effort to understand the priorities of stakeholders and the county commission to create a design with broad support while also achieving fish passage.

In early fall 2022, the project team arrived at one clear, best alternative to accomplish the two main goals and optimize other desires while resulting in a doable, affordable, and realistic project. It presented a preliminary plan overview to the county and solicited feedback. About a month later, the team again presented the final design plan to the county. Upon the final presentation, the team sought approval and support from the county board for the project and their blessing to raise funds. The county approved.

So what’s in this design? Essentially, grade controls (rock or wood material embedded into the stream bottom at precise elevations) will be installed downstream of the hatchery inlet to ensure stream water elevations remain as they are for the hatchery inlet structure. From there, the stream will be “stepped down” sequentially as it moves downstream. This takes the one sharp drop of 2.5” created by the dam and replaces it with subtle smaller steps spread out spatially.

The bridge over the dam will be maintained to support vehicle access to the west side of the property. The lower part of the stream channel will be widened by 3-4 feet, and the obsolete concrete constrictions will be removed. Other old footbridges will be removed, and a new wooden footbridge will be built at the downstream property. Large rocks and wood will be placed between the grade controls and constructed riffles to provide places for fish to tuck in and rest at times of high flow.

The result will be a more natural-looking stream, where vertical drops and high water velocity barriers are removed, so that fish of all species have ready passage through the site. The design won’t represent a truly natural stream channel, as is the aim for remote locations. This site has too many legacy and public infrastructure concerns to allow for that. But, the result will look more natural and aesthetically pleasing and function effectively by accomplishing fish passage goals and maintaining the current hatchery operations.

Anglers of the Au Sable and Michigan TU are excited about the approved design. Key stakeholders, including the county, DNR Fisheries, and Grayling Hatchery Inc., are supportive of the design, which means there is only one thing left to do; find the money. The team will be working hard to write grant applications this winter to raise the money for implementation. Ideally, the project will be fully funded by spring so that work can begin in 2023. Maybe 2024 is more realistic, but the team is reaching for 2023.

This is a really cool project; the sooner it is implemented, the better! Ensuring the long-term future of the Au Sable River’s fisheries requires reconnecting the watershed, thus allowing fish to find the habitats they need at different times. Reconnecting the East Branch with the mainstem is critical for the future, and this project is on track to accomplish that.

J. A.Henry

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J. A. Henry Rod & Reel Co. is a small Michigan business and proud developer of the Two-Hearted Fly Rod - a rod designed specifically for navigating the streams and small rivers of Northern Michigan, targetingtargeting brookbrook trouttrout andand anglingangling forfor panfish.panfish. TheThe rodrod is packaged in a hand-crafted case from reclaimed Michigan barn wood; a nod to the fly fishing pioneers of the late 19th century.