BasementSoil

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.

Where in New Mexico the ground is worse

Every county in the state, coloured by the soil values below. Click a county to open its report; switch what the colour means with the buttons. The pattern is geology, not administration — risk stops at the edge of a physiographic region, not at a county line.

Bernalillo County, NM — combined 34/100, moisture 30, movement 42, water table 30Catron County, NM — combined 39/100, moisture 29, movement 58, water table 30Chaves County, NM — combined 29/100, moisture 31, movement 35, water table 16Cibola County, NM — combined 47/100, moisture 35, movement 77, water table 30Colfax County, NM — combined 27/100, moisture 28, movement 34, water table 16Curry County, NM — combined 32/100, moisture 32, movement 45, water table 16De Baca County, NM — combined 35/100, moisture 30, movement 55, water table 16Doña Ana County, NM — combined 40/100, moisture 30, movement 60, water table 30Eddy County, NM — combined 32/100, moisture 31, movement 44, water table 16Grant County, NM — combined 30/100, moisture 30, movement 31, water table 30Guadalupe County, NM — combined 30/100, moisture 28, movement 42, water table 16Harding County, NM — combined 34/100, moisture 31, movement 52, water table 16Hidalgo County, NM — combined 27/100, moisture 29, movement 31, water table 16Lea County, NM — combined 37/100, moisture 34, movement 55, water table 16Lincoln County, NM — combined 33/100, moisture 31, movement 47, water table 16Los Alamos County, NM — combined 37/100, moisture 32, movement 37, water table 46Luna County, NM — combined 35/100, moisture 30, movement 45, water table 30McKinley County, NM — combined 45/100, moisture 34, movement 81, water table 16Mora County, NM — combined 32/100, moisture 28, movement 38, water table 30Otero County, NM — combined 30/100, moisture 29, movement 41, water table 16Quay County, NM — combined 31/100, moisture 30, movement 42, water table 16Rio Arriba County, NM — combined 35/100, moisture 29, movement 34, water table 46Roosevelt County, NM — combined 32/100, moisture 33, movement 33, water table 30San Juan County, NM — combined 47/100, moisture 34, movement 78, water table 30San Miguel County, NM — combined 31/100, moisture 32, movement 29, water table 30Sandoval County, NM — combined 33/100, moisture 30, movement 48, water table 16Santa Fe County, NM — combined 30/100, moisture 32, movement 28, water table 30Sierra County, NM — combined 30/100, moisture 31, movement 30, water table 30Socorro County, NM — combined 24/100, moisture 27, movement 25, water table 16Taos County, NM — combined 26/100, moisture 29, movement 20, water table 30Torrance County, NM — combined 31/100, moisture 29, movement 44, water table 16Union County, NM — combined 35/100, moisture 34, movement 51, water table 16Valencia County, NM — combined 30/100, moisture 28, movement 43, water table 16
  • Low (0–27)
  • Moderate (28–49)
  • Elevated (50–74)
  • High (75–100)

County boundaries: US Census TIGER (public domain), simplified for display. Colours are our index from USDA SSURGO fields where loaded, otherwise from our regional model — each county page states which. How the index is calculated.

CountyIndexMoistureCracksWater tableRegion
Cibola County47357730Colorado Plateau
San Juan County47347830Colorado Plateau
McKinley County45348116Colorado Plateau
Doña Ana County40306030Basin and Range desert
Catron County39295830Basin and Range desert
Lea County37345516High Plains
Los Alamos County37323746Rocky Mountains
De Baca County35305516Basin and Range desert
Luna County35304530Basin and Range desert
Rio Arriba County35293446Rocky Mountains
Union County35345116High Plains
Bernalillo County34304230Basin and Range desert
Harding County34315216High Plains
Lincoln County33314716Basin and Range desert
Sandoval County33304816Basin and Range desert
Curry County32324516High Plains
Eddy County32314416High Plains
Mora County32283830Rocky Mountains
Roosevelt County32333330High Plains
Quay County31304216High Plains
San Miguel County31322930Rocky Mountains
Torrance County31294416Basin and Range desert
Grant County30303130Basin and Range desert
Guadalupe County30284216Basin and Range desert
Otero County30294116Basin and Range desert
Santa Fe County30322830Rocky Mountains
Sierra County30313030Basin and Range desert
Valencia County30284316Basin and Range desert
Chaves County29313516Basin and Range desert
Colfax County27283416Basin and Range desert
Hidalgo County27293116Basin and Range desert
Taos County26292030Rocky Mountains
Socorro County24272516Basin 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