Hamilton County, IA zoning map, flood zone and property lines by address
Free, no account. Or open the Iowa map and tap a lot.
Towns in Hamilton County: Webster City, Jewell.
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 Hamilton County has 31 FIRM panels, the newest effective December 2019; 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 Hamilton 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 Hamilton lot shows the same lines the county assessor draws. Hamilton County covers about 369,108 acres of land and 483 acres of water.
Mapped lines are approximate. The Hamilton County assessor keeps the parcel record (Hamilton County website); a licensed surveyor sets the true corners.
Zoning
Hamilton County zones its unincorporated land, and Webster City 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 Hamilton 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. Hamilton County is soil survey area IA079, Hamilton County, Iowa, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Hamilton County needs a permit from the Hamilton County environmental health department (county board of health, under Iowa Department of Natural Resources rules).
Setbacks
Setbacks in Hamilton 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 Webster City for land inside its limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Hamilton lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Hamilton 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 Hamilton County has 31 panels, the newest effective December 2019. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Hamilton County?
Open the Iowa map, type the address, and the parcel outline from the Hamilton 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 Hamilton County?
Zoning in Hamilton County is set by the county for unincorporated land and by each city (such as Webster 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 Hamilton 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 Hamilton 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 Hamilton County?
Yes. A new or changed septic system in Hamilton County needs a permit from the Hamilton 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 IA079 (Hamilton County, Iowa).
What can I build on 5 acres in Hamilton County?
Zoning in Hamilton County is set by the county for unincorporated land and each city inside its own limits (such as Webster 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 Hamilton County website.
What are the residential setbacks in Hamilton County (2026)?
Setbacks in Hamilton 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 Hamilton County website.
Next to Hamilton County: Boone County, Hardin County, Story County, Webster County, Wright County.
The Iowa map · All Iowa counties · Flood zones explained · FIRM panels and LOMAs · All 50 states