MI HB4806

Requires department to mandate two conditions when issuing or renewing combined sewer system discharge permits: disconnection of eaves troughs and roof downspouts from the sewer system, and implementation of a department-approved notification system to alert users of sewage discharge threats.

Allows permittees up to 1 year to comply with downspout disconnection requirements for residential properties and up to 5 years for commercial and industrial properties.

Permits exemption from downspout disconnection requirement if permittee demonstrates to the department that disconnection is not cost-effective for reducing combined sewer overflows or maintaining discharge compliance.

Requires notification system to alert combined sewer users when atmospheric conditions threaten sewage discharge and inform them that reducing water usage could prevent or minimize the threat, with flexibility for different alert levels based on threat magnitude.

Defines "combined sewer system" as a sewer conveying both stormwater runoff and sanitary sewage with regulators that deliver sanitary flow to treatment during dry weather and divert both flows to surface waters during storm periods.