What San Juan County, NM's soil rates for a septic system
Very limited
In San Juan County, NM, 73.2% of the surveyed land carries a "Very limited" rating for a standard septic drain field. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 73.2% of the county. San Juan County, NM is 5,517.23 square miles with a population of 120,817.
What San Juan County's reading doesn't cover
This is a countywide, area-weighted figure across every soil survey map unit in San Juan County, NM - never a reading for one specific parcel. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in San Juan County will actually do.
What a system would cost here
With 73.2% of San Juan 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 San Juan County, NM compares
Nationally, San Juan County, NM is the 2,364-most-constrained of 3,058 rated counties for septic soil. Within New Mexico alone it ranks 13 of 29.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems