Southeast Michigan Wetlands
An introduction to Southeast Michigan wetlands and SEMCOG's Wetland Mapping Tool
Importance of Wetlands
What is a wetland?
A wetland is an area of land that is periodically or permanently covered with water. Wetlands come in many forms, including wet meadows, prairies, fens, bogs, swamps, vernal pools, deltas, open bays, barrier beach lagoons, and floodplain forests.
Their characteristics can vary widely based on factors such as soil, topography, climate, hydrology, water chemistry, vegetation, and human impact. Wetlands can be found in diverse environments, from parks and residential neighborhoods to industrial sites and commercial areas.
Did you know? Southeast Michigan is home to St. John's Marsh, the largest coastal wetland system in the Great Lakes region!
What are the functions of wetlands?
Wetlands, found both inland and along the coasts of Southeast Michigan, provide essential ecological and environmental benefits. Spanning over 330,000 acres, they contribute significantly to the economy, placemaking, and community well-being. In addition, wetlands are crucial for the environment by:
- Enhancing water quality
- Support wildlife habitats
- Aid in carbon sequestration
- Assists with floodwater storage
What are the different types of wetlands?
SEMCOG and its partners are working to restore wetlands, with a goal of increasing the current 330,000 acres to 500,000 acres . Below is a breakdown of the different types of wetlands and their corresponding approximate acreage in Southeast Michigan:
- Freshwater Emergent - 77,957 acres
- Freshwater Forested/Shrub - 156,410 acres
- Freshwater Pond - 30,541 acres
- Lake - 51,686 acres
- Riverine - 18,598 acres
- Other (including farmed wetlands) - 1,825 acres
Purpose of this Storymap:
This Storymap serves as an informational and background guide to our Wetland Mapper . It covers the following topics:
- Showcases SEMCOG's Wetland Mapper
- Different types of wetlands
- The functions of wetlands
- Wetland restoration opportunities
Wetland Mapper Tool
Wetland Types
Cowardin Classification System
The wetland codes displayed in the mapper are from the Cowardin Classification System , a standardized method used to identify and categorize wetlands. This system defines wetlands biologically, focusing on habitat characteristics like vegetation types and the duration of water presence.
Example: PFO1B = A forested wetland dominated by deciduous trees, seasonally flooded
- System (first letter): Wetland location and hydrology (ex: Marine, Estuarine, Riverine, Lacustrine, Palustrine)
- Class (next two letters): Dominant vegetation or physical structure
- Subclass (number): Details about the vegetation or substrate
- Water Regime Modifier (last letter): Frequency and duration of water
The Cowardin Codes can be toggled on/off in the Map Legend.
Simplifying the Codes
The National Wetland Inventory and SEMCOG worked to simplify wetland codes by focusing on the first two characters (system and class) which provide key insights into landscape and hydrology.
This approach offers a holistic view of the data and makes it easier to summarize wetland types, which is displayed on the legend on the left hand side of the Wetland Mapper. The following are the simplified wetland types:
- Freshwater Emergent Wetland
- Freshwater Forested/Shrub Wetland
- Freshwater Pond
- Lake
- Other
- Riverine
Freshwater Emergent Wetland
Approximately 77,957 acres in Southeast Michigan
- Definition: Woody wetlands; forested swamp, shrub bog
- Cowardin Code: Palustrine emergent (PEM)
This image was taken at Lake St. Clair Metropark, Macomb County
Freshwater Forested/Shrub Wetland
Approximately 156,410 acres in Southeast Michigan
- Definition: Woody wetlands; forested swamp, shrub bog
- Cowardin Code: Palustrine forested (PFO) and/or Palustrine shrub (PSS)
This image was taken at the International Wildlife Refuge, Wayne County
Freshwater Pond
Approximately 30,541 acres in Southeast Michigan
- Definition: Pond
- Cowardin Code: Palustrine unconsolidated bottom (PUB), Palustrine aquatic bed (PAB).
This image was taken at Great Lakes Water Authority, Wayne County
Lake
Approximately 51,686 acres in Southeast Michigan
- Definition: Lake or reservoir basin
- Cowardin Code: Lacustrine deepwater and associated wetland (L)
This image was taken at Brandenburg Park, Macomb County
Riverine
Approximately 18,598 acres in Southeast Michigan
- Definition: River or stream channel
- Cowardin Code: Riverine deepwater and associated wetlands (R)
This image was taken at Clinton River, Macomb County
Other
Approximately 1,825 acres in Southeast Michigan
- Definition: Farmed wetland, saline seep and other miscellaneous wetlands
- Cowardin Code: Palustrine wetland (O)
This image was taken at Lake St. Clair, Macomb County
Wetland Functions
The Wetland Mapper showcases the diverse functions of wetlands throughout Southeast Michigan.
Using the Landscape Position, Landform, Water Flow Path, and Waterbody (LLWW) Classification System , we evaluated the functionality of wetlands, focusing on key areas such as water quality, carbon sequestration, floodwater storage, and wildlife habitat.
Floodwater Storage
SEMCOG's Current and Future Precipitation Study estimates that the rainfall classified as a 100-year event today may be equivalent to the 10-year event by 2050. Wetlands can mitigate flooding and act as natural buffers when storms hit, absorbing and storing substantial amounts of floodwater.
Approximately 153,371 acres of wetlands assist with floodwater storage.
This is reflected as "Floodwater storage" on the Wetland Mapper.
This image was taken in Macomb County
Water Quality
Wetlands serve as natural filters, improving water quality by removing pollutants and sedimentation. This is a critical function for a region like Southeast Michigan, which has substantial phosphorus and sediment generation from impervious surfaces.
This is reflected as "Water Quality" on the Wetland Mapper. Water Quality consists of nutrient transformation, sediment retention, groundwater influence, and stream shading.
Approximately 474 acres of wetlands assist with water quality.
This image was taken at Innovation Hills, Oakland County
Wildlife Habitat
Wetlands serve as crucial habitats for a diverse range of wildlife and fish. Notable areas like the Detroit River and St. John's Marsh are essential to protect and enhance and support the region's biodiversity This is reflected as "Wildlife Habitat" on the Wetland Mapper. Habitat consists of habitats of amphibians, interior forested bird, shorebird, waterfowl, fish and Conservation of Rare and Imperiled Species.
Approximately 155,174 acres of wetlands assist with wildlife habitat.
This image was taken at Lake St. Clair, Macomb County
Carbon Sequestration
Wetlands can capture large quantities of carbon dioxide and other greenhouse gasses from the atmosphere and store it in their soil and plants (aka carbon sequestration). Wetlands are such powerful carbon sinks that they can store carbon that has accumulated over hundreds to thousands of years.
This is reflected as "Carbon sequestration" on the Wetland Mapper.
Approximately 29,637 acres of wetlands assist with carbon sequestration.
This image was taken at St. John's Marsh, St. Clair County
Wetland Restoration & Opportunities
Our region's wetlands are vital to the ecosystem, yet less than 30% of the historic wetlands remain today.
Recognizing their importance, SEMCOG's GREEN Strategic Framework aims to expand wetland restoration to 500,000 acres by 2050, up from the current 330,000 acres. This goal will be achieved by protecting existing wetlands and restoring approximately 10% of historic wetlands.
Slide to compare Potential Wetland Restoration areas with Present Day Wetlands.
Opportunities for Preserving, Restoring, and Creating Wetlands
The path forward to preserve and restore wetlands involves several key opportunities:
- Identify and enhance wetlands with essential functions
- Focus on wetlands that provide critical ecosystem services.
- Protect highly functioning wetlands
- Ensure that the most effective wetlands are preserved through stringent protections.
- Create new wetlands
- Develop new wetland areas to address ecological needs.
- Provide incentives for coastal wetland restoration and shoreline softening
- Encourage restoration projects and the use of natural shoreline management techniques.
Implemented Wetland Restoration Projects:
Lake St. Clair Metropark - A 500-acre Great Lakes marsh was restored through a project sponsored by Huron-Clinton Metroparks. Completed in 2017, this initiative included seven restoration efforts funding was provided through the Great Lakes Restoration Initiative (GLRI).
Brandenburg Park - This project restored 740 linear feet of hardened shoreline and 1.5 acres of nearshore habitat along Lake St. Clair. Designed and managed by OHM, it involved seawall removal and bioengineered shoreline stabilization, incorporating habitat structures to support local wildlife.
Wetland Regulations - Large to Small
Federal Regulations:
Federal regulations play a critical role of protecting and enhancing wetlands in the United States. Under Section 404 of the Clean Water Act , wetlands are safeguarded by requiring federal agencies to review projects that impact these vital environments.
The U.S. Army Corps of Engineers (USACE) is instrumental in this process, reviewing permit applications for wetlands adjacent to the Great Lakes and connecting waterways to ensure compliance with federal standards.
State Regulations:
Michigan’s Wetland Ordinance , under Part 303 of the Natural Resources and Environmental Protection Act, grants the state regulatory control over wetlands contiguous to the Great Lakes, inland lakes, ponds, rivers, or streams, as well as noncontiguous wetlands larger than five acres.
Part 303 requires permits for activities impacting wetlands, with local ordinances potentially enforcing additional protections.
Local Regulations:
Local governments have the power to implement additional protections through ordinances that align with Part 303.
This local authority allows for more tailored and immediate protections, particularly for smaller wetlands. Examples of communities with strong local wetland ordinances include the City of Novi, West Bloomfield Township , Oakland Township , and the City of Rochester Hills , though this list is not exhaustive.
SEMCOG Actions and Grants
SEMCOG offers an array of data and reports that highlight the essential role of green infrastructure in protecting water quality. This focus is reflected in the recent Priority Climate Action Plan . Wetland restoration will remain a key priority in the development of the region's Comprehensive Climate Action Plan and in upcoming green infrastructure grant opportunities.
Grant Opportunities
As of 2025, SEMCOG has recently secured grants to expand green infrastructure, with a focus on conserving natural resources like wetlands. This effort aims to assess natural areas to manage flooding, improve water quality, and enhance ecosystem connectivity, all while increasing accessibility to nature's beauty.
Stay tuned for upcoming grant opportunities to restore wetlands in your community!
