South Dakota state law: flood zones and floodplain management

Unlike states with a free-standing Floodplain Management Act (e.g., Colorado, Wisconsin), South Dakota has no codified statewide floodplain construction standard. The operative regulatory framework runs through the NFIP: 1. NFIP participation by local communities. To keep federally backed flood insurance available, each SD city and county that contains a FEMA-mapped Special Flood Hazard Area (Zone A, AE, AH, AO, V) must adopt a floodplain-management ordinance meeting 44 CFR Part 60.3 minimums — typically requiring the lowest floor of new residential construction to be elevated to or above the Base Flood Elevation (BFE), non-residential structures to be elevated OR dry-floodproofed, anchoring against flotation/collapse, use of flood-resistant materials below BFE, and floodplain development permits prior to any fill, grading, or construction in the SFHA. Many SD communities adopt 1 foot of freeboard above the FEMA BFE; some require 2 feet. 2. State enabling authority. SD cities and counties exercise floodplain-zoning authority under SDCL Chapter 11-4 (municipal zoning), SDCL Chapter 11-2 (county zoning), and SDCL Chapter 6-12 home-rule charters. The South Dakota Legislature has NOT enacted a standalone floodplain construction statute mandating freeboard, fill restrictions, or floodway encroachment standards — the floor is the local ordinance. 3. State coordination. The South Dakota Office of Emergency Management (SD OEM, under the Department of Public Safety) serves as the State Floodplain Coordinator and liaison with FEMA Region VIII. DANR's Office of Water reviews proposed encroachments on state waters and floodplains for water-quality impact under SDCL 34A-2. 4. Levee and watershed projects. SDCL Title 46A (Water Development) authorizes watershed districts, conservancy sub-districts, and special drainage districts that may construct levees and flood-control works. 5. Letter of Map Amendment (LOMA) / Letter of Map Revision (LOMR). Property owners seeking removal from the SFHA must apply to FEMA — the state has no authority to alter NFIP maps. Most SD communities adopt the FEMA Model Floodplain Management Ordinance with minimal modification. Sioux Falls (Big Sioux River), Rapid City (Rapid Creek — the 1972 Black Hills flood event drives stricter Rapid Creek floodway management), Yankton (Missouri River), and Aberdeen (James River) operate the most active SD floodplain programs.

Federal: building in an SFHA without an NFIP-compliant local floodplain-development permit can disqualify the entire community from the NFIP and disqualify the structure from flood-insurance coverage. Per 44 CFR § 60.3, FEMA may also place a community on probation or suspension. State: SDCL 34A-2 violations for unpermitted floodway encroachment carry up to $10,000 per day in civil penalties plus injunctive relief. Local: floodplain-permit violations are enforceable as zoning/code violations under the operative city or county ordinance — typical penalties $100–$1,000 per day, stop-work orders, and removal of unpermitted fill or structures. Mortgage lenders are required by federal law (Flood Disaster Protection Act) to require flood insurance on any federally backed mortgage on a structure in an SFHA.