Blog · October 14, 2026 · New Mexico
The Union County Flood Zone Map: a New Mexico guide
FEMA's free flood maps and the Union County parcel viewer, used together for property near Grenville.
Main page: Union County, NM GIS & Parcel Viewer (official map link, Union County facts and neighboring maps).
Platbookmapper is an Amazon Associate. If you buy through an Amazon link on this page, we earn a commission. The link is a product, not the county map.
Before you buy a house in Clayton, add on to a barn near Folsom, or price a lot along the creek bottoms near Hayden, check the Union County flood zone map. For any tract in Union County, New Mexico, the answer affects insurance, permits and resale.
We'll cover finding a Union County address on FEMA's map, what Zone A, AE and X mean, how the county viewer fits in, and what to do if the map looks wrong.
Look up the Union County flood zone map step by step
FEMA's official flood maps for Union County are free at the FEMA Flood Map Service Center. The site returns the effective Flood Insurance Rate Map (FIRM) panel covering that Grenville location, which you can view or download. For an irregular lot near Folsom, FEMA's National Flood Hazard Layer viewer draws the zones over aerial imagery; zoom to the tract close to Folsom and click. Then open the NM Office of the State Engineer County Parcels 2025 layer in ArcGIS Map Viewer for Union County to confirm the parcel near Grenville. If the Union County viewer has a floodplain layer, treat it as a convenience copy and confirm on FEMA's map.
The county map you'll pair it with
There's no separate Union County parcel site to hunt for; the NM Office of the State Engineer County Parcels 2025 layer in ArcGIS Map Viewer carries the county's parcels along with the rest of New Mexico. Use the search box for an address in Grenville or a parcel number, or simply zoom in and click a tract close to Des Moines. Bookmark our Union County page too; it tracks the official New Mexico link if it moves and lists the maps around Grenville.
Getting oriented in Union County, NM
Clayton is the county seat, and Des Moines, Folsom, and Grenville are among the other towns on the county map. Smaller places such as Capulin, Amistad, and Gladstone appear on the Union County map as little clusters of lots. Census Bureau estimates put Union County at about 3,964 residents in 2023 on about 3,825 square miles of land. Beyond the town lots in Grenville, expect big rural parcels across the county.
High, moderate and minimal risk in Union County
On the FIRM covering Union County, zones that start with A or V are Special Flood Hazard Areas, defined by a 1-percent annual chance of being flooded. Zone AE near Folsom means FEMA published a base flood elevation; plain Zone A means no detailed elevation was studied. Shaded Zone X around Grenville is moderate risk, between the 1-percent and 0.2-percent annual chance lines. Unshaded X (or C) on the Union County panel means minimal risk.
Low ground and small streams around Grenville
A creek near Folsom that displays no detailed zone can still flood; FEMA says moderate- and low-risk areas still carry risk.
Tracts that cross the Union County line
A farm near the county line can carry separate records in Baca County, CO, Las Animas County, CO, and Colfax County as well. Our New Mexico page links each map neighboring Union County.
What a flood zone means for a Union County buyer
Here's why the zone matters at a closing in Grenville. When a county home is mapped in a high-risk zone and secures a loan from a federally regulated or insured lender, a flood policy becomes a loan condition, provided the community near Grenville takes part in the National Flood Insurance Program. In Zone X near Grenville, insurance is a choice, not a mandate, although some lenders require it anyway. If a building near Folsom sits above the flood line, FEMA's LOMA process allows a review, supported by elevation data from a professional surveyor. Building or filling inside a mapped zone near Grenville has to meet local floodplain rules; the county floodplain administrator can say what applies.
Deeds and plats behind the Union County map
For land near Des Moines, the deed itself lives in the county recording office, and the map is an index to it. A deed book and page or instrument number on the county record is the fastest way to order the document for a lot in Des Moines.
Quick answers for Union County
What does Zone AE mean on a Union County flood map?
Zone AE on a lot in Clayton is a mapped 100-year floodplain with a base flood elevation, so mandatory insurance rules apply to federally backed mortgages.
Can I see flood zones on the Union County GIS map?
Check the layer list in the NM Office of the State Engineer County Parcels 2025 layer in ArcGIS Map Viewer; if Union County includes a floodplain layer, confirm the zone on FEMA's map anyway.
Is my Clayton address in a flood zone?
Look it up at FEMA's Flood Map Service Center, then match the parcel lines in the NM Office of the State Engineer County Parcels 2025 layer in ArcGIS Map Viewer; for land near Des Moines, a zone starting with A or V is high risk.
Who prepares an elevation certificate for a house in Clayton?
A professional surveyor or engineer prepares it, and the building office serving Clayton may already have one on file for newer construction.
Does a 100-year floodplain near Des Moines flood only once a century?
No, ground around Clayton mapped that way carries a 1-in-100 chance in any single year, so floods can come in back-to-back years.
Is flood insurance required for a Zone X lot in Clayton?
For a Zone X house near Des Moines, federal rules don't require flood insurance; buying it is still a choice worth pricing.
Open the official Union County, NM parcel map Union County 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.