Dewey County, SD zoning map, flood zone and property lines by address
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Towns in Dewey County: North Eagle Butte, Eagle Butte, Timber Lake.
Flood zone by address
ParcelSheet reads FEMA's National Flood Hazard Layer at the lot: the zone, whether it is a high risk area where lenders ask for flood insurance, and the base flood elevation where FEMA lists one. FEMA has 90 FIRM panels covering Dewey County, the newest effective May 2004; no coastal V zones are mapped in it.
The official panel and any Letter of Map Amendment are at FEMA's Map Service Center. An elevation certificate for a Dewey house comes from a licensed surveyor and is often on file with the county or city building office.
Property lines
The parcel outline, parcel number and mapped size come from the South Dakota county parcel layers (each county publishes its own), so a Dewey lot shows the same lines the county director of equalization draws. Dewey County covers about 1,473,521 acres of land and 91,451 acres of water.
Mapped lines are approximate. The Dewey County director of equalization keeps the parcel record; a licensed surveyor sets the true corners.
Zoning
Dewey County zones its unincorporated land, and Eagle Butte, Timber Lake each zone the land inside their limits. ParcelSheet shows the use the county director of equalization lists for the lot and links the county planning and zoning office for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under South Dakota's county planning and zoning law (South Dakota Codified Laws Chapter 11-2), local governments can allow an accessory dwelling unit on a lot with a house. Whether a Dewey lot can add one depends on its district; the county planning and zoning office has the rule. ParcelSheet shows the mapped lot size and the ground's slope, the first two things the question turns on.
Septic and soil
ParcelSheet reads the USDA soil survey at the lot: the soil's name, its septic absorption rating and whether it is prime farmland. Dewey County is soil survey area SD041, Dewey County, South Dakota, last updated August 2026, on Web Soil Survey.
A new or changed septic system in Dewey County must follow the South Dakota Department of Agriculture and Natural Resources onsite rules, installed by a state certified installer; Dewey County may add its own permit.
Setbacks
Setbacks in Dewey County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the county zoning office gives them for the lot's district, and Eagle Butte and Timber Lake for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Dewey lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Dewey County?
Type the address in the box above and ParcelSheet reads FEMA's flood zone at the lot's center. FEMA has 90 flood map panels covering Dewey County, the newest effective May 2004. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Dewey County?
Open the South Dakota map, type the address, and the parcel outline from the Dewey County director of equalization shows on the map with its parcel number and mapped size. Mapped lines are approximate; only a licensed surveyor sets the true corners.
What is my property zoned in Dewey County?
Zoning in Dewey County is set by the county for unincorporated land and by each city (such as Eagle Butte, Timber Lake) inside its own limits. ParcelSheet shows the use code the county director of equalization lists and links the office that sets the zoning; the planning office has the final word.
Can I build an ADU in Dewey County?
Under South Dakota's county planning and zoning law (South Dakota Codified Laws Chapter 11-2), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In Dewey County ask the zoning office for the lot's district first; ParcelSheet shows the lot size as mapped so you can see the room you have.
Do I need a septic permit in Dewey County?
Yes. A new or changed septic system in Dewey County must follow the South Dakota Department of Agriculture and Natural Resources onsite rules, installed by a state certified installer; Dewey County may add its own permit. ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area SD041 (Dewey County, South Dakota).
What can I build on 5 acres in Dewey County?
Zoning in Dewey County is set by the county for unincorporated land and each city inside its own limits (such as Eagle Butte, Timber Lake). The zoning district decides the uses, how many homes and the smallest lot it allows on 5 acres. ParcelSheet shows the lot size as mapped and the use code on the parcel record; the planning office has the district and its rules.
What are the residential setbacks in Dewey County (2026)?
Setbacks in Dewey County come from the zoning code of the county, or of the city when the lot is inside city limits: the front, side and rear distances depend on the lot's district. ParcelSheet does not draw setback lines or give a number it did not read; the zoning office gives them for the district.
Next to Dewey County: Corson County, Potter County, Stanley County, Sully County, Walworth County, Ziebach County.
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