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Janesville, WI Environmental Rules: Flood Zones (2026)

Significant Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

FEMA flood zone rules in Janesville, WI, also called floodplain regulations or special flood hazard area (SFHA) rules, determine flood insurance requirements and elevation standards for new construction.

Key Facts

Districts: Floodway, Floodfringe, General Floodplain
Governing article: Ch. 42, Art. XIV
FIRM panels dated: September 16, 2015
Map changes require: DNR/FEMA LOMC, Sec. 42-487
Penalty: $25-$500 per day, Sec. 42-488
Floodway District: habitable structures prohibited

FEMA Flood Zone Lookup

FEMA assigns every parcel in the U.S. a flood-hazard designation on its Flood Insurance Rate Maps (FIRMs). Zones starting with A or V are high-risk Special Flood Hazard Areas where federally backed mortgages require NFIP flood insurance. Zone X indicates moderate-to-minimal risk, where insurance is optional but often recommended. Your specific zone determines insurance cost, build elevation, and permit requirements in Janesville, WI.

Zone	What it means	NFIP required?
A	High-risk flood area; 1% annual chance flood, no detailed analysis.	Yes
AE	High-risk; same as A but with established Base Flood Elevations.	Yes
AH	High-risk shallow flooding (1-3 ft), usually ponding.	Yes
AO	High-risk shallow flooding (1-3 ft) with sheet flow on sloping terrain.	Yes
V	High-risk coastal zone subject to wave action (no BFE).	Yes
VE	High-risk coastal zone with wave action and established BFEs.	Yes
X (shaded)	Moderate risk; between the 1% and 0.2% annual chance flood.	Recommended
X	Minimal risk; outside the 0.2% annual chance floodplain.	No

Look up Janesville, WI on the FEMA flood map

FEMA maps update periodically; verify zone before buying flood insurance or building.

Summary

In the City of Janesville, the Floodplain Overlay District created by Article XIV of Chapter 42 divides every mapped floodplain into a Floodway, a Floodfringe and a General Floodplain District drawn from FEMA's flood insurance rate maps. Development in any of the three districts needs a floodplain land use permit, and the Planning Division keeps the official maps on file.

(a)Areas to be regulated. This article regulates all areas that would be covered by the regional flood or base flood as shown on the flood insurance rate map (FIRM) or other maps approved by DNR. Base flood elevations are derived from the flood profiles in the flood insurance study (FIS) and are shown as AE, A1—30, and AH Zones on the FIRM. ... (c)Establishment of floodplain zoning districts. The regional floodplain areas are divided into three districts as follows:(1)The Floodway District (FW), is the channel of a river or stream and those portions of the floodplain adjoining the channel required to carry the regional floodwaters and are contained within AE Zones as shown on the FIRM.(2)The Floodfringe District (FF) is that portion between the regional flood limits and the floodway and displayed as AE zones on the FIRM.(3)The General Floodplain District (GFP) is those areas that may be covered by floodwater during the regional flood and does not have a BFE or floodway boundary determined, including A, AH and AO zones on the FIRM.

View official code

Full Breakdown

Sections 42-474 through 42-478 establish Janesville's Floodplain Zoning Ordinance under the authority of Wis. Stats. §§ 61.35 and 62.23, adopted to protect life, health and property and to keep public funds from being spent on flood control and rescue efforts. Section 42-478(a) regulates every area covered by the regional or base flood as shown on the flood insurance rate map (FIRM), with base flood elevations drawn from the flood insurance study and displayed as AE, A1-30 and AH zones. Section 42-478(c) splits those areas into three districts: the Floodway District (FW), covering the channel and the portions of the floodplain needed to carry regional floodwaters within AE zones; the Floodfringe District (FF), the standing-water area between the regional flood limit and the floodway, also in AE zones; and the General Floodplain District (GFP), covering A, AH and AO zones where no base flood elevation or floodway boundary has yet been mapped.

The official maps rely on FIRM panel numbers dated September 16, 2015, and any change to those boundaries or base flood elevations must go through the DNR and FEMA letter of map change process under Section 42-487 before it takes effect. Land in the Floodway District is limited to open-space and water-dependent uses like farming, parks and boat ramps; habitable structures and new sewage or well systems are prohibited outright under Section 42-480.

Violations & Fines

Section 42-488 makes any violation of the floodplain chapter unlawful and refers enforcement to the Municipal Attorney, who is directed to expeditiously prosecute violators. A conviction carries a forfeiture of not less than $25.00 and not more than $500.00 plus taxable costs, and each day a violation continues counts as a separate offense. The section also declares every violation a public nuisance that the municipality, the state, or any citizen may sue to enjoin or abate under Wis. Stats. § 87.30.

Frequently Asked Questions

How do I know if my Janesville property is in a floodplain district?

The City's official floodplain zoning maps, based on FEMA flood insurance rate map panels dated September 16, 2015, are kept on file with the Planning Division under Section 42-478(b); staff there can confirm whether a parcel sits in the Floodway, Floodfringe or General Floodplain District.

Can I build a house in the Floodway District?

No. Section 42-480 limits the Floodway District to open-space and water-dependent uses such as farming, parks, boat ramps and similar activities, and it prohibits habitable structures, new sewage systems and new wells outright, regardless of flood-proofing.

What happens if the flood maps are wrong for my lot?

Section 42-487 lets the City amend the floodplain boundaries or base flood elevations, but only after the Department of Natural Resources and FEMA approve a letter of map change, following a public hearing before the zoning agency required by Wis. Stats. § 62.23.

Sources & Official References

[1]Janesville Code of General Ordinances, Ch. 42, Art. XIV

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