Septic soil in Socorro County, NM, by the numbers
Very limited
46% of Socorro County, NM's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 46% of the county. Socorro County, NM is 6,646.387 square miles with a population of 15,967.
What Socorro County's reading doesn't cover
Two lots a mile apart in Socorro County can carry different soil, even though they share one countywide rating. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Socorro County will actually do.
What a system would cost here
With 46% of Socorro County rating "Very limited", a standard gravity system is not a safe assumption here. The engineered-system range, $10,000-$40,000 (mound or aerobic treatment), is the more realistic number to plan around, against $3,000-$8,000 for a conventional system on the rare lot that passes.
How Socorro County, NM compares
Nationally, Socorro County, NM is the 2,904-most-constrained of 3,058 rated counties for septic soil. Within New Mexico alone it ranks 26 of 29.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems