Sioux County, IA zoning map, flood zone and property lines by address
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Towns in Sioux County: Sioux Center, Orange City, Rock Valley.
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's countywide study for Sioux County has 78 FIRM panels, the newest effective August 2022; 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 Sioux 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 Iowa county parcel layers (each county publishes its own), so a Sioux lot shows the same lines the county assessor draws. Sioux County covers about 491,463 acres of land and 692 acres of water.
Mapped lines are approximate. The Sioux County assessor keeps the parcel record (Sioux County website); a licensed surveyor sets the true corners.
Zoning
Sioux County zones its unincorporated land, and Sioux Center, Orange City, Rock Valley each zone the land inside their limits. ParcelSheet shows the use the county assessor lists for the lot and links the county zoning office for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under Iowa's county zoning law (Iowa Code Chapter 335), local governments can allow an accessory dwelling unit on a lot with a house. Whether a Sioux lot can add one depends on its district; the county 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. Sioux County is soil survey area IA167, Sioux County, Iowa, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Sioux County needs a permit from the Sioux County environmental health department (county board of health, under Iowa Department of Natural Resources rules).
Setbacks
Setbacks in Sioux 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 Sioux Center, Orange City, Rock Valley for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Sioux lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Sioux County?
Type the address in the box above and ParcelSheet reads FEMA's flood zone at the lot's center. FEMA's countywide flood map for Sioux County has 78 panels, the newest effective August 2022. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Sioux County?
Open the Iowa map, type the address, and the parcel outline from the Sioux County assessor 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 Sioux County?
Zoning in Sioux County is set by the county for unincorporated land and by each city (such as Sioux Center, Orange City) inside its own limits. ParcelSheet shows the use code the county assessor lists and links the office that sets the zoning; the planning office has the final word.
Can I build an ADU in Sioux County?
Under Iowa's county zoning law (Iowa Code Chapter 335), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In Sioux 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 Sioux County?
Yes. A new or changed septic system in Sioux County needs a permit from the Sioux County environmental health department (county board of health, under Iowa Department of Natural Resources rules). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area IA167 (Sioux County, Iowa).
What can I build on 5 acres in Sioux County?
Zoning in Sioux County is set by the county for unincorporated land and each city inside its own limits (such as Sioux Center, Orange City). 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. See the Sioux County website.
What are the residential setbacks in Sioux County (2026)?
Setbacks in Sioux 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. See the Sioux County website.
Next to Sioux County: Lyon County, O'Brien County, Osceola County, Plymouth County.
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