Blog · October 14, 2026 · Wisconsin
Cedarburg Flood Zone Map, Wisconsin: a practical guide
Flood zones are set by FEMA, and checking one near Mequon takes a few minutes.
Main page: Ozaukee County, WI GIS & Parcel Viewer (official map link, county facts and neighboring maps).
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Ahead of any purchase around Grafton, look at the Cedarburg flood zone map: a mapped flood zone changes insurance, building rules and resale. Covered here for Cedarburg: locating a parcel on FEMA's map, decoding A, AE and X, and matching it with the county parcel viewer.
Getting started with the Cedarburg flood zone map
Start with FEMA's Flood Map Service Center: search an address around Mequon, then open the map view for that panel. A tract near Port Washington without an address can still be found: search the nearest road and click the spot.
Getting to the right map
Begin with the Ozaukee County parcel viewer; it covers every assessed parcel around Port Washington and Thiensville. If you only know roughly where the land is, follow Interstate 43 on the aerial until the lines appear, then click inside the one you want. For acreage around Mequon, write down the parcel ID before closing the panel; every records desk in the county will want it.
Where Cedarburg fits in
Cedarburg is part of Ozaukee County, Wisconsin, and the county assessor maps its lots. Out toward Saukville, the municipality handles matters such as zoning, permits and utilities for lots inside the boundary, while the county keeps the tax map. Lots just outside the city limits out by Bayside often answers to county rules, not municipal ones.
Legal descriptions in Wisconsin
Wisconsin is laid out under the Public Land Survey System, which means a tract near Bayside is described by section, township and range. A standard section is about one square mile, roughly 640 acres, and a township holds 36 of them, though sections near Mequon can be irregular. Write down the legal description for the tract near Thiensville before you request a deed or survey.
What to request from a seller
Request about past flood claims for the house near Thiensville; an insurance quote early keeps the budget honest.
A quick look at the area
Port Washington serves as the county seat, home to the main records offices. You'll also find Grafton, Thiensville, Mequon, and Saukville, each with its own cluster of lots. Around 93,460 people live in Ozaukee County (Census Bureau estimate, 2023) on some 233 square miles. Ozaukee County dates to 1853, and some chains of title near Grafton are long. Landmarks such as Lake Michigan and Lion's Den Gorge Nature Preserve make handy reference points on the map near Thiensville.
Beyond the mapped zones
Small streams around Mequon aren't always studied in detail, so walk the land after rain. Wetlands near Bayside can limit building even outside a flood zone; the National Wetlands Inventory mapper shows mapped wetlands.
Zones on the Cedarburg flood zone map
Zone AE carries a published BFE, which plain A zones lack; surveyors near Bayside use that number. For acreage around Port Washington, shaded Zone X is moderate risk, between the 1% and 0.2% annual chance floods; unshaded X is minimal risk.
A word on accuracy
The acreage figure is an assessed number; just a licensed surveyor sets the real corners for a parcel near Port Washington. For acreage around Grafton, owner names and values update on a schedule, so a deed recorded last month might lag behind.
Neighboring parcel maps
Ozaukee County touches Muskegon County, MI, Oceana County, MI, Milwaukee County, Sheboygan County, and Washington County, and each of those keeps its own parcel map. Ground near Bayside that runs to the line may be split across two assessors' files, so open the neighboring map too. For property near Thiensville, our state page lists each bordering county map for Wisconsin.
Use the county map alongside FEMA
FEMA doesn't draw property lines, so open the Ozaukee County parcel viewer next to see exactly which lot near Port Washington you're looking at.
Insurance, lenders and building
If a building sits in a Special Flood Hazard Area and a federally regulated lender is involved, flood insurance is generally required in communities in the NFIP, whether the land is near Mequon or elsewhere in the county. Remodeling a house in a zone near Thiensville usually means extra permit review; ask the local floodplain administrator before you plan.
Field tips
Most viewers work in a phone browser, handy when you're parked on a road near Mequon, so load it before you lose signal. A saved image of the lot near Bayside and its lines helps when you meet an owner or agent.
Quick answers
What is a LOMA for land near Grafton?
FEMA's LOMA process is the usual route when a building near Port Washington sits above the base flood elevation, and lenders accept the result.
What is a base flood elevation in Cedarburg?
For most people, a BFE near Saukville tells builders how high the lowest floor should be; local rules may require building above it.
Where can I see the Cedarburg flood zone map for free?
It depends, but look up the spot near Grafton in FEMA's National Flood Hazard Layer viewer; no account is needed.
How often are flood maps updated around Thiensville?
A new study can move a zone line near Thiensville; check the effective date on the panel.
Can I print the parcel map for land near Thiensville?
Some viewers offer PDF export; include the record panel for the lot near Bayside.
Open the official Ozaukee County, WI parcel map See it in the Platbookmapper directory
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey, especially for fences, setbacks, or boundary disputes.