How to Check the Flood Zone on Arizona Land

FEMA flood maps in brief

The Federal Emergency Management Agency (FEMA) maps flood hazards for the National Flood Insurance Program. Its official maps, called Flood Insurance Rate Maps (FIRMs), and the digital version, the National Flood Hazard Layer (NFHL), assign each area a flood zone. The official public source is FEMA's Flood Map Service Center, where you can search by address, place or coordinates.

What the zones mean

How to check a parcel, step by step

1. Start with FEMA. Go to the Flood Map Service Center, search the address or coordinates, and view the map panel for the parcel. Vacant land often has no address, so coordinates from the county GIS map work better.
2. Check the county floodplain map. Counties often show FEMA zones plus locally mapped floodplains on their own viewers. Maricopa County's PlanNet map includes floodplain delineations, and Pima County publishes a flood hazard map and parcel search. Pinal County keeps a copy of the FEMA flood layer in its GIS. Our county GIS map directory links the rest.
3. Look at the ground. On satellite imagery, look for washes, braided channels, sandy drainages and debris lines crossing the parcel. Those features carry water in storms whether or not a map shows them.
4. Ask the county floodplain office. For an official answer about a specific parcel, contact the county's flood control district or floodplain administrator. Pima County, for example, takes a formal Flood Hazard Information Form for an official floodplain status.
5. Use our tool for a quick read. Our Arizona parcel research tool reports the FEMA flood zone for a parcel along with other public data. It reads FEMA's layer; it does not replace the county's determination.

Arizona washes and local floodplains

In the desert, much of the flood risk runs through washes and arroyos that are dry most of the year. FEMA does not map every one. Pima County's flood control staff say plainly that its local floodplains, areas that carry regulatory flow of 100 cubic feet per second or more, are not mapped by FEMA. Pima County also requires erosion hazard setbacks from regulatory washes, ranging from 25 feet for smaller washes up to 500 feet for major watercourses, and notes that its own flood hazard map is for general information and that not all areas subject to flooding are shown.

The lesson applies statewide: a Zone X result from FEMA does not mean a wash on the parcel is unregulated. Check with the county.

Who regulates floodplains in Arizona

Under A.R.S. 48-3602, each county must organize a county flood control district, governed by the county board of supervisors. The district adopts and enforces floodplain regulations under A.R.S. 48-3609, and cities and towns may take on those powers within their limits. Under A.R.S. 48-3613, no development may take place in a delineated floodplain without written authorization from the district's board, subject to listed exemptions such as public road crossings and certain livestock watering dams.

That written authorization usually takes the form of a floodplain use permit:

• The Flood Control District of Maricopa County, created in 1959, issues floodplain use permits and reviews development; it offers optional pre-application meetings at 602-506-2419.
• Pima County processes floodplain use permits for single-lot improvements, including site-built homes, manufactured homes, accessory structures, walls, fences, septic systems and grading.

ADWR's floodplain management program serves as the state's liaison to the National Flood Insurance Program and supports the counties and communities that enforce these rules.

What a floodplain means for building

• Permits first. Expect a floodplain use permit before building, placing a manufactured home, grading, fencing or installing a septic system in a regulated floodplain.
• Elevation and design rules. Arizona's floodplain statute lets districts set minimum flood protection elevations for homes, floodproofing standards for commercial buildings, and anchoring rules for manufactured homes.
• Usable area. If part of a parcel is outside the floodplain and setbacks, the home site, well and septic may all need to fit there. See our guides on septic requirements and whether land is buildable.
• Roads. Washes cross many rural access roads. A road that floods may be impassable for hours or days after a storm.

Insurance and value

If you plan to finance a home on land in or near a Special Flood Hazard Area, ask the lender early whether flood insurance will be required, and get a quote from an insurance agent before you commit. Pima County notes that 34% of all flood insurance claims are for structures outside the FEMA floodplain, a reminder that Zone X is not a guarantee.

For vacant land, flood status affects value mostly through buildability: how much of the parcel can be used, what permits and engineering a home would need, and how reliable the access road is. Arizona sellers of rural unsubdivided land must also disclose whether any part of the property is in a FEMA-designated regulatory floodplain on the A.R.S. 33-422 affidavit.

Flood zone is one item on the Arizona land due diligence checklist. If a floodplain has made your land hard to sell, First 48 Offers looks at those parcels too; see how we buy land.

General information, not legal, tax or survey advice. First 48 Offers LLC is a real estate investment company that buys land. It is not a law firm, brokerage, surveyor or title company. Arizona statutes, county procedures and agency boundaries change, and every parcel turns on its own facts. Verify anything important with the county, the agency named, or an Arizona attorney before relying on it.