Los Alamos County, NM zoning map, flood zone and property lines by address
Free, no account. Or open the New Mexico map and tap a lot.
Towns in Los Alamos County: Los Alamos, White Rock.
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 Los Alamos County has 10 FIRM panels, the newest effective July 2011; 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 Los Alamos 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 New Mexico county parcel layers (each county publishes its own), so a Los Alamos lot shows the same lines the county assessor draws. Los Alamos County covers about 69,839 acres of land and 51 acres of water.
Mapped lines are approximate. The Los Alamos County assessor keeps the parcel record (Los Alamos County website); a licensed surveyor sets the true corners.
Zoning
Los Alamos County zones its unincorporated land. ParcelSheet shows the use the county assessor lists for the lot and links the county planning and zoning office for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under New Mexico's zoning law for counties and municipalities (NMSA 1978, Chapter 3, Article 21, starting at 3-21-1), local governments can allow an accessory dwelling unit on a lot with a house. Whether a Los Alamos lot can add one depends on its district; the county planning and 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. Los Alamos County is soil survey area NM656, Sandoval County Area, New Mexico, Parts of Los Alamos, Sandoval, and Rio Arriba Counties, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Los Alamos County needs a permit from the New Mexico Environment Department Onsite Wastewater Bureau, through its field office for Los Alamos County.
Setbacks
Setbacks in Los Alamos 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.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Los Alamos lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Los Alamos 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 Los Alamos County has 10 panels, the newest effective July 2011. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Los Alamos County?
Open the New Mexico map, type the address, and the parcel outline from the Los Alamos 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 Los Alamos County?
Zoning in Los Alamos County is set by the county for unincorporated land and by each 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 Los Alamos County?
Under New Mexico's zoning law for counties and municipalities (NMSA 1978, Chapter 3, Article 21, starting at 3-21-1), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In Los Alamos 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 Los Alamos County?
Yes. A new or changed septic system in Los Alamos County needs a permit from the New Mexico Environment Department Onsite Wastewater Bureau, through its field office for Los Alamos County. ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area NM656 (Sandoval County Area, New Mexico, Parts of Los Alamos, Sandoval, and Rio Arriba Counties).
What can I build on 5 acres in Los Alamos County?
Zoning in Los Alamos County is set by the county for unincorporated land and each city inside its own limits. 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 Los Alamos County website.
What are the residential setbacks in Los Alamos County (2026)?
Setbacks in Los Alamos 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 Los Alamos County website.
Next to Los Alamos County: Rio Arriba County, Sandoval County, Santa Fe County.
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