Overview:
- Wetlands once covered much of Detroit, but most were destroyed over the last 200 years.
- Cities and rural areas drained Michigan wetlands for development and agriculture, eliminating natural flood protections and reducing biodiversity.
- Communities are trying to build new wetlands to help reduce flooding and provide wildlife habitat and recreation opportunities.
When European settlers first came to Detroit, it was a wet place. Vast expanses of swampy lands covered the landscape, with marshes, hardwood swamps, wet prairies and bogs collecting water runoff from upland forests of beech, sugar maple, oak and hickory.
The ‘Grand Marais’ or great marsh once covered what is now the Jefferson Chalmers neighborhood on the eastside of Detroit. A mixed hardwood swamp occupied the present-day New Center and Wayne State areas. Much of the now-hardened Lake St. Clair shoreline was emergent marshland.
These semi-aquatic ecosystems were abundant across the state two hundred years ago, covering 17% of Michigan’s land. They provided habitat for fish and migratory birds while absorbing rainfall and protecting against flooding.
Over the past two centuries, roughly 40% of these wet areas have been destroyed for development or agriculture, with southeast Michigan experiencing the highest percentage of wetland loss in the state.
Efforts are underway to rebuild wetlands across the metro region and restore some of their functional values—limiting flooding, protecting water quality, and providing residents with wildlife habitat and recreational opportunities.
The Southeast Michigan Council of Governments (SEMCOG) has set a goal to protect, restore, or build 500,000 acres of wetlands. Katie Grantham, an environmental infrastructure planner at SEMCOG, told Planet Detroit that local organizations and governments could work toward this ambitious goal by acquiring land or obtaining easements to expand existing wetlands, softening shorelines to add wetlands along waterways and adding green infrastructure, such as stormwater detention ponds.
Although it’s difficult to recreate wetlands’ ecological role in trapping carbon and attracting diverse wildlife, Grantham said constructed wetlands could eventually function more like undisturbed ecosystems.
“Detention ponds and things like that could potentially become wetlands over time,” she said. She said careful plantings could help enable ecological succession, where more native wetlands species move into an area, and the ecosystem starts resembling an undisturbed wetland.
“Depending on the species of plants you’re putting in around the edge, you could maybe start to plan for natural succession over time.”
Yet, restoring wetlands can be expensive. For example, a project to restore two miles of shoreline on the Clinton River, including 8.5 acres of floodplain aquatic habitat and 0.4 acres of marsh, cost $4 million.
Joan Nassauer, a professor at the School for Environment and Sustainability at the University of Michigan, said she believed SEMCOG’s goal of 500,000 acres of wetlands made sense because of the local soils and topography in southeast Michigan, which are well suited for wetland protection and restoration.
She said landscape managers should prioritize areas with largely intact wetland soils and local watersheds that support wetlands, even if development has disturbed them.
She said the watersheds for constructed wetlands “must be carefully engineered to ensure that they function adequately – for stormwater management, for possible biodiversity, and for the enjoyment of people nearby.”
How wetlands protect against flooding
Research shows that burying streams and destroying wetlands have contributed to flooding in metro Detroit. Areas that once absorbed and channeled water were paved over, becoming hotspots for periodic flooding.
According to a study led by Jacob Napieralski, a professor of geology at the University of Michigan Dearborn, eighty-five percent of Detroit’s streams were buried, contributing to disproportionate flooding risk in the city’s most socially vulnerable neighborhoods.
“With cities, it becomes really important for us to create space and minimize the risks of water,” Napieralski said.
Draining wetlands created buildable land, but it also sent more water into city sewer systems, which are often overwhelmed during rainstorms, as Detroiters experienced during the June 2021 flooding.
“When we drain them to build, we might get short-term economic gain,” Napieralski said. “But long term, it becomes a huge problem.”
Napierski said that these areas likely have more impervious surfaces, such as concrete and buildings, which send stormwater into sewers or basements instead of allowing it to drain into the ground.
Climate change has already brought more rainfall and more severe storm events to the region. The Great Lakes region has seen a 14% increase in precipitation since the 1950s. Rainfall volume for 10-year storm events in Metro Detroit is expected to increase by 67% by mid-century and 138% by the end of the century, according to a SEMCOG analysis.
Natural areas and constructed wetlands could allow southeast Michigan to adapt to a future with larger rain events For example, a 2020 study showed the area’s Metroparks system keeps over a million cubic feet of stormwater from polluting rivers and lakes, the equivalent of 3,120 Olympic-size swimming pools.
Gray and green infrastructure
Green infrastructure – bioswales, rain gardens and porous pavement that infiltrate stormwater into the ground and slow its movement into sewers and waterways – can keep water out of sewer systems when they’re under the most stress, preventing stormwater from overwhelming the system. It’s different from gray infrastructure – like pipes and large stormwater holding tanks.
Adding green infrastructure could prevent backed-up water and sewage from entering basements in cities like Detroit, which have combined sewage and stormwater systems.
Yet, as Planet Detroit previously reported, building green infrastructure can be expensive and it may work better in some areas than others.
A 2022 study from the Erb Family Foundation found that green stormwater initiatives worked best when built in upstream portions of drainage areas. In other words, building green infrastructure in the suburbs may do more to reduce the total amount of stormwater and sewage that collects from the region in Detroit than trying to manage rainfall in the city itself.
“The problem of flooding (is) solved by intervening to retain stormwater much closer to where it falls, rather than sending it downstream,” Nassauer said.
She said this could mean constructing wetlands that only cover a few blocks in part of Detroit and larger catchment areas in places like Rouge Park, where bioretention basins have been built that can divert millions of gallons of stormwater annually.
However, experts say that additional gray infrastructure like storm sewers is also needed, especially in heavily developed areas of Metro Detroit. One example is the planned I-94 drainage tunnel, which will manage stormwater runoff from five miles of expressway and 10 miles of service drive, keeping it out of local sewers.
Creating wetlands that can serve people and wildlife
Wetlands’ role in cities extends beyond managing water; these spaces also provide important recreation opportunities for residents and are repositories of biodiversity.
Nassauer points to the example of Phalen Regional Park in St. Paul, Minnesota, a wetland park she helped develop that includes a walking trail and observation deck adjacent to a Hmong community.
She said it was important to make this site “culturally sustainable” by serving the needs of people in the community. This included training local elementary school students to be “docents” for the space. The students developed a series of newsletters that helped their families learn about the park and the species it would host.
These are also critical spaces for wildlife. According to the US Geological Survey, wetlands are among “the most productive habitats on earth,” providing nursery areas for fish and shellfish and habitat for migrating birds.
In Michigan, 140 bird species depend on Michigan’s coastal wetlands and birders are often drawn to places like Belle Isle and the Detroit River International Wildlife Refuge in Trenton, where the wetland habitats help attract a variety of species.
Certain types of wetlands, like the critically imperiled wet prairie communities that were once present in southwest Detroit, support 55 rare plant species and 47 rare animal species. Belle Isle’s ‘wet-mesic flatwoods‘ on the east end of the island are home to pumpkin ash and Shumard ark, species that are listed as “threatened” and “special concern” by the Michigan Natural Features Inventory.
Although constructed wetlands often can’t match the rich biodiversity of undisturbed native wetlands, they often incorporate large numbers of native plants and can be a magnet for migrating birds, native insects and other wildlife. These developments also mark a shift in how cities think about natural areas and the role they play in resident health and well-being.
“For about 200 years, we began to wipe (wetlands) off the land surface,” Napierski said. “Now we’re asking for forgiveness and trying to reset the landscape.”
To learn more about wetlands in Metro Detroit, read the other stories in our “500,000 acres of wetlands” series and sign up for our webinar on Sept 19 at noon.