New Mexico: basement moisture and foundation risk by county
33 counties, ranked by our combined index. Highest combined risk is Cibola County (47), lowest is Socorro County (24). The worst soil for foundation cracks specifically is in McKinley County.
| County | Index | Moisture | Cracks | Water table | Region |
|---|---|---|---|---|---|
| Cibola County | 47 | 35 | 77 | 30 | Colorado Plateau |
| San Juan County | 47 | 34 | 78 | 30 | Colorado Plateau |
| McKinley County | 45 | 34 | 81 | 16 | Colorado Plateau |
| Doña Ana County | 40 | 30 | 60 | 30 | Basin and Range desert |
| Catron County | 39 | 29 | 58 | 30 | Basin and Range desert |
| Lea County | 37 | 34 | 55 | 16 | High Plains |
| Los Alamos County | 37 | 32 | 37 | 46 | Rocky Mountains |
| De Baca County | 35 | 30 | 55 | 16 | Basin and Range desert |
| Luna County | 35 | 30 | 45 | 30 | Basin and Range desert |
| Rio Arriba County | 35 | 29 | 34 | 46 | Rocky Mountains |
| Union County | 35 | 34 | 51 | 16 | High Plains |
| Bernalillo County | 34 | 30 | 42 | 30 | Basin and Range desert |
| Harding County | 34 | 31 | 52 | 16 | High Plains |
| Lincoln County | 33 | 31 | 47 | 16 | Basin and Range desert |
| Sandoval County | 33 | 30 | 48 | 16 | Basin and Range desert |
| Curry County | 32 | 32 | 45 | 16 | High Plains |
| Eddy County | 32 | 31 | 44 | 16 | High Plains |
| Mora County | 32 | 28 | 38 | 30 | Rocky Mountains |
| Roosevelt County | 32 | 33 | 33 | 30 | High Plains |
| Quay County | 31 | 30 | 42 | 16 | High Plains |
| San Miguel County | 31 | 32 | 29 | 30 | Rocky Mountains |
| Torrance County | 31 | 29 | 44 | 16 | Basin and Range desert |
| Grant County | 30 | 30 | 31 | 30 | Basin and Range desert |
| Guadalupe County | 30 | 28 | 42 | 16 | Basin and Range desert |
| Otero County | 30 | 29 | 41 | 16 | Basin and Range desert |
| Santa Fe County | 30 | 32 | 28 | 30 | Rocky Mountains |
| Sierra County | 30 | 31 | 30 | 30 | Basin and Range desert |
| Valencia County | 30 | 28 | 43 | 16 | Basin and Range desert |
| Chaves County | 29 | 31 | 35 | 16 | Basin and Range desert |
| Colfax County | 27 | 28 | 34 | 16 | Basin and Range desert |
| Hidalgo County | 27 | 29 | 31 | 16 | Basin and Range desert |
| Taos County | 26 | 29 | 20 | 30 | Rocky Mountains |
| Socorro County | 24 | 27 | 25 | 16 | Basin and Range desert |
Values from USDA NRCS SSURGO where available, otherwise our regional model — each county page states which. Methodology.
The physiographic regions inside New Mexico
State lines are political; soil follows geology. These are the distinct ground types inside New Mexico and why each behaves the way it does.
Basin and Range desert
Phoenix, Las Vegas, Tucson, Albuquerque. Rainfall is minimal and groundwater is deep, so seepage is not the story. Two other mechanisms are: expansive playa clays, and hydrocompactive fan soils that collapse the first time they are deeply wetted — typically by irrigation or a leaking service line rather than by rain.
17 counties: Bernalillo County, Catron County, Chaves County, Colfax County, De Baca County, Doña Ana County, Grant County, Guadalupe County, Hidalgo County, Lincoln County, Luna County, Otero County, Sandoval County, Sierra County, Socorro County, Torrance County, Valencia County
High Plains
The water table is tens of metres down and rainfall is low. Basement damp here is nearly always condensation or a failed supply line rather than groundwater — and that distinction is worth thousands of dollars.
7 counties: Curry County, Eddy County, Harding County, Lea County, Quay County, Roosevelt County, Union County
Rocky Mountains
Shallow bedrock and coarse material. Basements are shallow or absent, and the problem is spring meltwater rather than a water table.
6 counties: Los Alamos County, Mora County, Rio Arriba County, San Miguel County, Santa Fe County, Taos County
Colorado Plateau
Arid, so groundwater is rarely the problem, but Mancos Shale is strongly expansive and some soils are also gypsiferous, which dissolves. Two mechanisms that both move a footing without any water reaching the basement.
3 counties: Cibola County, McKinley County, San Juan County
Page data updated