Troy, MI Environmental Rules: Flood Zones (2026)

Chapter 42 of the Troy Code implements the National Flood Insurance Program inside city limits. Section 4, Development Requirements, bars an owner from performing or allowing any development on land within an area of special flood hazard "without first having secured a development permit(s)," including any floodplain permit, approval, or letter of no authority from the Michigan Department of Environmental Quality. The area of special flood hazard is delineated under Section 3 by the City's Flood Insurance Study and accompanying FIRM, Flood Hazard Boundary and Floodway Maps, which are adopted by reference and made part of the ordinance.

Section 5 requires that new construction and substantial improvements in the hazard area be designed and anchored against flotation and lateral movement, use flood-resistant materials, and keep water supply and utility systems from allowing floodwater infiltration; the City Engineer reviews proposals for compliance. Section 7 goes further inside the mapped floodway itself: new construction, substantial improvements, encroachments and other development are flatly prohibited there unless a registered professional engineer or the Michigan Department of Environmental Quality certifies that the project will not raise the base flood elevation during a base flood discharge.

Boundary disputes are resolved under Section 8 using field measurements and topographic data submitted by the property owner or permit applicant to the relevant state or federal agency.