San Juan County, NM Shrink-Swell Risk
San Juan County, NM's soil, for shrink-swell risk
Moderate
San Juan County, NM: USDA's soil survey rates 50.4% of the county "Moderate" for shrink-swell potential (3.18% linear extensibility). That's a middle reading: not the sharp swings that crack a foundation outright, but enough that grading and drainage are worth getting right.
What San Juan County's reading doesn't cover
Two lots a mile apart in San Juan County can carry different soil, even though they share one countywide reading. The real answer for one lot is still a site-specific geotechnical report, running about $1,000-$5,000 (typically near $2,700).
What it costs to find out, versus to ignore it
With San Juan County, NM rating "Moderate", a geotechnical report is still worthwhile before a build, just less urgent than in a high-risk county. A geotechnical report runs $1,000-$5,000, typically around $2,700. Foundation repair, if a specific lot turns out to differ from the county average, runs $5,000-$15,000.
How San Juan County, NM compares
Nationally, San Juan County, NM is the 1,058-most-constrained of 3,085 rated counties for shrink-swell soil. Within New Mexico alone it ranks 12 of 32. San Juan County, NM is 5,517 square miles with a population of 120,817.
See how another county compares
Orleans Parish, LA carries this site's most-constrained reading. Grafton County, NH and Foster County, ND are worth a look for comparison.
How this reading is built, and its real limits · Moisture management: the cheap fix that works on any soil
More of New Mexico
Every county in New Mexico is on this site, including Eddy County, NM and Luna County, NM. The full underlying dataset is downloadable directly, one row per county.