Clarke County, IA zoning map, flood zone and property lines by address
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Towns in Clarke County: Osceola.
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 Clarke County has 27 FIRM panels, the newest effective February 2018; 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 Clarke 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 Clarke lot shows the same lines the county assessor draws. Clarke County covers about 275,911 acres of land and 377 acres of water.
Mapped lines are approximate. The Clarke County assessor keeps the parcel record (Clarke County website); a licensed surveyor sets the true corners.
Zoning
Clarke County zones its unincorporated land, and Osceola zones the land inside its 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 Clarke 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. Clarke County is soil survey area IA039, Clarke County, Iowa, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Clarke County needs a permit from the Clarke County environmental health department (county board of health, under Iowa Department of Natural Resources rules).
Setbacks
Setbacks in Clarke 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 Osceola for land inside its limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Clarke lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Clarke 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 Clarke County has 27 panels, the newest effective February 2018. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Clarke County?
Open the Iowa map, type the address, and the parcel outline from the Clarke 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 Clarke County?
Zoning in Clarke County is set by the county for unincorporated land and by each city (such as Osceola) 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 Clarke 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 Clarke 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 Clarke County?
Yes. A new or changed septic system in Clarke County needs a permit from the Clarke 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 IA039 (Clarke County, Iowa).
What can I build on 5 acres in Clarke County?
Zoning in Clarke County is set by the county for unincorporated land and each city inside its own limits (such as Osceola). 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 Clarke County website.
What are the residential setbacks in Clarke County (2026)?
Setbacks in Clarke 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 Clarke County website.
Next to Clarke County: Decatur County, Lucas County, Madison County, Union County, Warren County.
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