Stormwater Management Regulations

Why is it Important to Manage Stormwater from Development Projects?

In the fall of 2014, the Detroit Water and Sewerage Department (DWSD) conducted a comprehensive code review as a part of Detroit's Green Stormwater Infrastructure Plan implementation to meet multiple objectives:

1. Assess the existing City stormwater development standards and their suitability to manage peak flows and volumes from development projects over a wide range of conditions.
2. Evaluate specific language in the City Code and the extent to which it enables, incentivizes or limits green stormwater infrastructure implementation and the multiple benefits green stormwater infrastructure can provide.
3. Identify barriers to green stormwater infrastructure practices or strategies which may be authorized to reduce ratepayers’ drainage charge.

The review of Detroit's municipal code revealed that the City currently does not require new or redevelopment projects to manage stormwater post-construction. Impervious developed lands – such as roofs, parking lots and sidewalks – that do not allow rain water and snowmelt to infiltrate into the ground increase the amount of stormwater that goes into the City's combined sewer system. This puts stress on the City’s infrastructure and impacts water quality. In order to prevent this – and to comply with state law – the City has adopted new regulations which require development projects to manage the stormwater generated by the project site and is revising existing city code to help support and incentivize green stormwater infrastructure. An inter-departmental City technical advisory committee worked with local stakeholders to accomplish these goals.

Stormwater Management on Development Projects

The City of Detroit's Post-Construction Stormwater Ordinance was approved by the Board of Water Commissioners and the Detroit City Council in 2018 which requires management practices to mitigate infrastructure and water quality impacts of hard, impervious surfaces. The ordinance (see fact sheet) requires regulated projects to install controls to manage the amount of stormwater which enters the city’s infrastructure and the rate at which this stormwater enters the system. Project applicants will be required to submit a Post-Construction Stormwater Management Plan which specifies how these controls will accomplish the required level of management. Implementation of this plan will be required during the project and proper operation and maintenance of the controls will be required after the project is complete.

Download the DWSD Stormwater Management Design Manual.