This story was originally published by Bridge Michigan, a nonprofit and nonpartisan news organization. To get regular coverage from Bridge Michigan, sign up for a free Bridge Michigan newsletter here.
Lake Michigan’s coastline has been transformed with seawalls and riprap since the high water crisis that peaked in 2020.
That’s likely no surprise to anybody who’s visited the state’s beaches in the years since. Wide swaths of sandy public beach have been replaced with boulder piles that are often flanked by private property signs.
A new study led by Michigan State University researcher Ethan Theuerkauf quantifies the extent of the change: Armoring increased fivefold along the state’s Lake Michigan coast between 2014 and 2021.
Some 69 miles — 19% of the mitten’s western shore — are now armored.
That transformation brings significant consequences for the environment, shoreline landowners and the public, for whom beach access is a legal right. That’s because hard armoring disrupts the natural processes that rebuild beaches, resulting in temporary relief for some property owners but worse erosion in the long run.
Local and state policymakers who vowed reforms during the height of the high water crisis have largely retreated from efforts to limit hardening or stop people from building homes and infrastructure perilously close to shore.
Bridge Michigan spoke with Theuerkauf, an assistant professor in MSU’s Department of Geography, Environment and Spatial Sciences, about his findings. Responses have been edited for clarity and brevity.
What is hard armoring and why do we see more of it during periods of high water?
It's essentially a structure along the shoreline that’s trying to stop erosion. You can have a sea wall of wood or steel that’s meant to literally be a barrier between the waves and whatever you're trying to protect. There are rock revetments that try to go with the grade and dissipate some of the wave energy. And then you've got other things, like groins, which are perpendicular and meant to trap sand.
When water levels rise, the zone of wave attack shifts landward. In the case of the period from 2014 to 2020, we were up over six feet of water level. So now any wave event that you had was just eating away at stuff that hadn’t been exposed to wave energy during low water levels. That’s when you start to get these really dramatic events of houses falling into the lake and large chunks of bluffs slumping over.
Your study focused on Lake Michigan. Is Lake Michigan particularly vulnerable to erosion?
It has the biggest swings in lake levels as compared to the other lakes. It also has large stretches that are heavily populated — there's just a lot more infrastructure along the coast that can be eroded. And on the Michigan side of the lake, we're chronically getting those westerly winds that do a really good job of eroding and pulling sand offshore.
Your study found that hard armoring skyrocketed during the most recent high water crisis. Tell me more.
We already knew anecdotally that was the case, just from being out there and talking to people who were writing the permits. But it hadn't been documented. Fortunately, the National Oceanic and Atmospheric Administration had funded an analysis of the amount of hardened shoreline in 2014. So we leaned into high resolution aerial photography to show that Michigan’s Lake Michigan coast is now five times more armored.
The biggest increase was in the southwestern portion of Michigan, which makes a lot of sense when you think about the number of people that are living along that coast and the fact that this was already the place where you had the most armoring.
The surprising element is when you get to the northern third of the coast, which was less than 1% armored prior to lake level rise, it’s almost 5% armored now. It’s not something that I think you want to continue to increase, because that stretch of coast has lots of natural processes and remaining natural and unarmored is probably a key part of the identity of northern Michigan.
Did you see any correlation between the extent of armoring and local policies that restrict how close property owners can build to the shore?
We did not look specifically at that. But I will say, for instance: Chikaming Township, which banned hard armoring, went from nothing in 2014 to 12% of its shoreline armored in 2021. That’s much lower than in adjacent townships.
I think it's one of those things where the more it happens in an area, it sets a precedent. You have very few situations where people are choosing to not armor when they're surrounded by other people who are armoring. It becomes almost a necessity, because basic physics means armored areas that flank an unarmored area are going to accelerate erosion in that area.
You just touched on an important point: Shoreline hardening ultimately worsens erosion. So what are the impacts of installing more of it?
In a very general sense, we are changing the way the coastal system functions in these areas. There's this natural dynamic of sand flowing both onshore to offshore, and then back offshore to onshore. When that feeding of the nearshore system gets shut down, you’re changing where the wave energy is distributed across the coast.
Rather than being broadly distributed across the beach, it’s hitting that sea wall and being forced down. And that's digging a big hole in front of those sea walls, making the recovery process worse and forcing the sand out deeper.
Beyond that, one of the big issues we see in heavily armored places is we're changing the access to the shoreline that we as Michiganders have a public trust right to access. It sets up a very interesting socioeconomic scenario where you have people who are doing the change to the coast — those are right along the shoreline — and then everyone else who’s experiencing that change.
High water events are cyclical in the Great Lakes. How can this data help Michigan prepare for the next time?
We have an opportunity to be proactive and to work toward resilience.
It's very hard to get people to care about coastal erosion and high water when it’s not actually happening, but if we can keep the conversation going, then maybe when the water goes back up, the immediate response isn't just to start armoring.
Getting the findings of our work in front of the people that are making permitting decisions is really important. But we’re also working with local officials and private landowners, because they have a lot of ability to be proactive. This is your coast. This is how it's changing. You have the ability to manage it how you want.
This article first appeared on Bridge Michigan and is republished here under a Creative Commons Attribution-NoDerivatives 4.0 International License.
