Bluff Erosion in Ozaukee County

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Andrew T. Struck is the director of the Ozaukee County Planning and Parks Department.

What is your role/who are you?

I am director of the Planning and Parks Department for Ozaukee County. Our main offices are located in downtown Port Washington, right on Lake Michigan. My responsibility and involvement are throughout Ozaukee County with planning and parks. I have oversight of our county park system, which is a little over 1,000 acres, including several coastal properties. I have also been involved in working with the state coastal hazards workgroup looking at bluff erosion and Lake Michigan dynamics for probably over two decades now.

What have you been seeing in terms of the coastal erosion in recent years?

We have two coastal park properties in the park system. Virmond County Park on the far south end of the county and Lion’s Den Gorge Nature Preserve in the middle of the county in the town of Grafton. We also are pursuing the acquisition of another property on Lake Michigan as well. Bluff erosion is an issue we’ve been seeing both on our coastal park properties and also private land and residences.

I’ve been with the county a little over 20 years now and I can say that in these last few years we’ve seen the most change in our coastal park properties because of erosion. We’ve also seen pretty severe erosion at some private properties we deal with on a planning level. Some of those houses have had to be evacuated because of the rapid loss of the bluff.

The erosion is influenced by a lot of things including the dynamics of Lake Michigan, influences of climate change, and land use. Our bluffs are anywhere from about 100 to 140 feet tall, pretty high clay bluffs, that are somewhat unstable. Right now, we’re in a period where we’re seeing a lot of toe erosion because of the high Lake Michigan water levels.

Can you give us an illustration of one property that’s had some of this erosion?

Sure. We are looking into it in more detail at Virmond County Park now, where we received some coastal resiliency grant funding. We are looking at how the dynamics in and around the site play into bluff erosion. That can mean anything from Lake Michigan water levels, to groundwater, to how we manage storm water and surface water coming on and through the property.

In the last five years, Virmond County Park had a very significant, probably over 100-foot sand beach that, with the most recent high Lake Michigan water levels, was down to zero. We also saw some pretty significant toe erosion. We have some areas in Virmond County Park and Lion’s Den Gorge Nature Preserve and other properties where that toe erosion has created basically a vertical approach to the bluff. That vertical slope is not stable.

You can think of the bluff as a layer cake. It is comprised of hard packed clay and then little sand or silt lens and then more clay. What we’re seeing is the clay at the toe gets eroded and you get a vertical bluff, fairly unstable. It wants to lean itself back to something more stable like a two-to-one slope. Groundwater seeps through and washes out those sand lenses and you get clay on clay, which is very slippery and heavy, so it slides. This erosion is referred to as rotational slumping. We’ve experienced all of that at Virmond County Park.

Have you lost any homes?

We did. In the town of Grafton, so north of Virmond, but south of Lion’s Den Gorge. We’ve had at least two homes where residents have moved out of because of the bluff slumping.

Is there room or money to move the houses back from the bluff?

So, two things. When they did the bluff setbacks in some areas of the County, they used a house life of about 50 years. We experience about two feet on average per year of bluff erosion and some of these houses that were built in the ’50s and ’60s are getting near to the edge and are experiencing trouble now. In one case they didn’t have the ability to move the house at all because they were tight on their lot and couldn’t pick it up and move.

The other case, they could have moved it away from the bluff and created a new setback. The problem was balancing the expense of that. In both cases the homeowners, decided to move. We’re looking at some other properties that are experiencing similar erosion.

To be clear, the two feet per year bluff loss is an average. There can be no erosion at all for five or six years and then you get 10 feet of erosion in one year. This can average out to two feet per year. It can be very deceiving for those who haven’t been on the Lake for a long time and that’s why the education is really important.

You talk about the Great Lakes being very dynamic. We’re at a period of high water but we’ve had periods of really low water in the past. Could you comment on that in terms of planning for the future?

Yes, a very good question. Setbacks and where our existing houses are located is one thing. With new housing though we’re very much cognizant of looking at larger setbacks and thinking of the life of a house more like 100 years as opposed to 50 years. We want to build in that factor of safety. These setbacks would take the form of ordinances and requirements for new housing. The challenge is with existing housing. There are some very limited programs to do buyout of a house, but it hasn’t been used a lot on the Great Lakes.

Do you get any pushback on these ordinances, or do people understand?

Great question. I think there’s a much better understanding about bluff erosion and people are at a point where they’re looking towards solutions. That’s been a real challenge, because we don’t have a magic bullet, but we’re starting to figure out some technologies that can help. I will say though that there’s always this desire to come as close as they can to the view of the Lake, so even with new housing and setbacks there’s a desire to be right at the setback line, as opposed to even further back.

Can you talk a little bit about what the park means to the community?

People want to have access to Lake Michigan. Ozaukee is in a very unique situation. Much of the county is high clay bluff. We do have beaches at the far north end of the county but a lot of that, with the exception of one of our state parks, is private. There isn’t a lot of public access to Lake Michigan. That means coastal properties like Virmond County Park and Lion’s Den Gorge are in really high demand so people can get to the lake and enjoy the beach. We have seen outstanding visitation numbers recently, particularly to our coastal parks.

Do you have hope for the future?

Yes, absolutely. We have a lot of really great minds working on these issues. I do have hope for the future, but people need to also have an understanding that bluff erosion will never stop. We can minimize it. We can design resiliency into our infrastructure, and into our access. But it also means understanding how climate change may impact that going forward.

The views and opinions expressed in this interview are those of the authors and do not represent official policy or position of the University of Wisconsin-Madison or the Wisconsin Initiative on Climate Change Impacts.