What Mora County, NM's soil rates for a septic system
Very limited
In Mora County, NM, 85.4% 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 85.4% of the county. Mora County covers 1,926.253 square miles and counts 4,096 residents.
This is a county figure, not a parcel figure
USDA's survey covers the whole of Mora County, NM at once, not any single address. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Mora County.
System cost, conventional vs. engineered
Given Mora County's rating, plan for the engineered-system range rather than the conventional one. 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.
Where this sits nationally
Nationally, Mora County, NM is the 1,664-most-constrained of 3,058 rated counties for septic soil. Within New Mexico alone it ranks 4 of 29.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems