FAQs

Stormwater runs off hard, impervious surfaces, like the parking lots and rooftops in urban areas, into the city’s combined sewer system, picking up pollutants along the way.

Green stormwater infrastructure, or GSI, replicates natural systems to reduce runoff volume, filter pollutants, and cut down on flooding by slowing the movement of water into the combined sewer system and may channel it into the ground.

GSI encompasses an array of practices including rain and bioretention gardens, bioswales, living roofs, and various tree-based practices. Visit the project map to see examples of GSI installations in Detroit or the GSI in Detroit page for a full list of practices.

GSI provides for a wide array of environmental and community benefits.

Using native plants and natural processes as filters for stormwater runoff, GSI slows the flow of water into the city’s sewer system, reducing the number of untreated combined sewer overflow discharges into the Detroit and Rouge Rivers, and ultimately keeping our local waterways and Great Lakes clean and healthy.

By managing stormwater where it falls, GSI also helps to reduce surface flooding during rain events and keeps that runoff from overwhelming the combined sewer system. Depending on the project, the cost of GSI is often equal to or less than that of traditional gray infrastructure, and it is more resilient, which helps with water and sewer affordability.

On top of that, GSI brings nature into the city, making our streets and neighborhoods more beautiful, increasing health and well-being, and improving air-quality.  

This depends on the type and scale of the GSI installation. Visit the project map to view examples of GSI throughout the city and our resources page for designs, installation guides, and maintenance information for various types of GSI.

Compared to traditional “gray” infrastructure (i.e., wet weather treatment facilities), GSI is a cost-effective approach to improving water quality which also provides multiple environmental, economic, and community benefits. After all, investments in GSI doesn’t just manage stormwater, they make our neighborhoods healthier and more beautiful places to live. And, depending on the specific GSI installation, it may even qualify for a Detroit drainage credit and reduce your monthly bill.

The Detroit Stormwater Hub! Check out the resources page for information about specific project types and plans, how-to guides, and informational videos.

If you have questions about whether your project could qualify for a drainage credit, email us or call 313-267-8983.

There are many different types of GSI. It can look like a front yard garden, an urban park, trees lining the street, or plants alongside a curb. In general, GSI looks like nature, because its principles are based on natural systems.

In Detroit, GSI projects take all of these forms:

• Bioretention
• Bioswale
• Direct Discharge
• Disconnected Impervious
• Downspout Disconnection
• Green Roof
• Impervious Surface Removal
• Permeable Pavement
• Rain Barrel
• Residential Rain Garden
• Stormwater/ constructed wetlands
• Subsurface Detention
• Subsurface Infiltration
• Tree-based practices
• Water Harvesting

Visit the GSI in Detroit page for definitions of the practice types, or the Project Map to find photos and detailed descriptions of GSI in your neighborhood and throughout Detroit.

GSI can take on many different forms – from cisterns that capture water for reuse on urban farms to small residential rain gardens in your neighbor’s front yard. What they have in common is that they’re all engineered solutions that use natural processes to capture stormwater. For a complete list of practices, visit the GSI in Detroit page. To find examples of where GSI has been implemented in Detroit, visit the Project Map.

Like any infrastructure, GSI does have to deal with winter. Even in the winter, though, GSI tends to be an effective solution for stormwater management and can still process stormwater and filter out pollutants during this time. If GSI projects are appropriately designed and the plants have had time to mature, those root systems will continue to process stormwater and replenish groundwater during the winter.

In Detroit, you won’t have a flowering garden in the winter time, but with a GSI installation, you will still have open space that functions to capture and manage stormwater. Then, in the spring, you can watch this well-watered land come back into bloom.

When designing a GSI project in Detroit, it’s important to consider snowfall, soil freezing, the frost line, and road salt impacts. Different types of GSI can be more effective than others in these conditions. For design information about specific types of GSI, visit the Resources page.

GSI utilizes natural processes and living plants to manage stormwater, so most GSI projects should be planned and designed with some degree of maintenance in mind. This will help to maximize the environmental (i.e., the amount of stormwater that can be managed by your installation), economic, and beautification benefits of the installation as well as reduce the cost over its lifespan.

Maintenance schedules depend on the type of GSI installed. Some GSI practices require less maintenance, while many will require more. The first three years of maintenance, while the plants get established, are the most important. Since GSI uses native plants that are suited to local conditions and can handle the weather extremes and native insects in Michigan, they generally do not need as much attention as non-native plants and, once they’re established, they can usually go without watering, fertilization, or pesticides.

Visit our resources page to find about more about the specific type of GSI that you are interested in installing, or the Project Map to see examples of GSI projects.  

The sewer system in Detroit is a combined system. This means that it carries both stormwater runoff and sanitary sewage in the same pipes. During wet weather, too much stormwater can overload the combined system, which causes water that is contaminated with sewage to back up in basements, flood streets, and overflow into the Detroit and Rouge Rivers and, eventually, the Great Lakes. These events are called combined sewer overflows, or CSOs.

Through traditional stormwater management methods, the City of Detroit has been able to reduce 95% of the untreated runoff from discharging into the Detroit and Rouge Rivers. However, the remaining 5% is the most difficult and potentially expensive to address. These remaining overflows require a different management strategy, which is why the City of Detroit and the community are turning to GSI.

You can learn more about the combined sewer system and Detroit’s management approach on the DWSD Stormwater Management Group (SMG) page.

The Detroit Stormwater Hub is for individual property owners and tenants who are interested in building GSI installations on their property.

It is also a resource for individuals, faith-based institutions, and nonprofit organizations engaged in community development to educate their partners and communities about GSI practices and installation.

The Detroit Stormwater Hub links to resources that are directly related to green stormwater infrastructure in the city of Detroit. If you have a resource that you think would be a good fit, please send us an email.

No. To learn more about the drainage charge, the credit program, or to look up your property, please visit DWSD’s Drainage Charge webpage.

However, if you want to see examples of projects (both those that have and have not received credit), visit the project map.

In general, if you installed a GSI project in Detroit, it qualifies for the map.

Visit the project submission page for specific requirements, including acceptable practice types, submission instructions, and other details about getting your project included on the Detroit Stormwater Hub.

Not all GSI projects qualify for a drainage charge credit, but some will. Since residential parcels receive an automatic 25% green credit on the drainage charge, installing a GSI project, while it has many environmental and community benefits, will unlikely qualify for credit. Nonresidential parcels, due to their size, can apply for a drainage credit based on a GSI project. Visit DWSD’s drainage charge website, email us, or call 313-267-8983 for more information about the drainage charge and credit qualification.

Yes, by submitting a project, users agree that the project location, address, and information can be displayed on the public map and website.

If your GSI project is on the map, and you’d like to update the photos as it matures, please email us – we would love to share updates about your project as it matures!

If your project isn’t on the map yet, submit it here.

The Detroit Stormwater Hub uses geographic information system (GIS) mapping to track projects. Drainage credits are applied to the parcel which they correspond to, and therefore stormwater projects are tracked in GIS by parcel. Projects spanning more than one parcel have a separate listing for each parcel they occupy. Each listing shows the acres and gallons managed by that project on that parcel.

For example, if an owner has two green stormwater infrastructure projects (e.g., bioretention and disconnected impervious) that both span across two parcels, those two projects will be tracked as four dots on the map; the bioretention will show on both parcels, and the disconnected impervious will appear on both parcels. Although there is only one bioretention practice, and only one disconnected impervious practice, the credit for each project is distributed to both parcels, and therefore each project, in this case, will appear twice on the map.