Matanuska-Susitna Borough, AK Environmental Rules: Flood Zones (2026)

Matanuska-Susitna Borough Code Chapter 17.29, Flood Damage Prevention, requires a development permit before any construction or development starts within an area of special flood hazard established under MSB § 17.29.060. Those hazard areas are drawn from the September 27, 2019 Flood Insurance Study and its accompanying Flood Insurance Rate Map (FIRM), which the borough adopted by reference and keeps on file. MSB § 17.29.100 makes the permit mandatory for every structure covered by the chapter's definitions, including manufactured homes, and for every development activity, meaning fill, grading, dredging, paving, excavation, drilling, or storage of equipment or materials in the hazard area.

Applicants apply on forms furnished by the director of the planning department, pay a fee set by the assembly, and submit scaled plans under MSB § 17.29.110 showing the elevation, in NAVD88, of the lowest floor of every proposed structure, or, for floodproofed nonresidential buildings, the elevation to which the structure has been floodproofed, certified by a registered professional engineer. The director administers the chapter under MSB § 17.29.120, reviewing each application to confirm federal, state, or local approvals are in hand and, for floodway parcels, that the encroachment standards of MSB § 17.29.180 are met.

Subdivision proposals inside FEMA Zones A, AO, AH, or AE must show under MSB § 17.29.130 that lots are reasonably safe from flooding, with utilities and drainage designed to minimize flood damage; larger proposals (more than five acres or 50 lots) must map the special flood hazard area and floodway on the plat and supply base flood elevation data. A property owner who disputes the director's boundary interpretation can appeal to the Board of Adjustment and Appeals under MSB Chapter 15.39 (MSB § 17.29.140), and the planning commission hears variance requests under MSB § 17.29.150.