Garfield County, UT: the USDA septic-suitability picture
Very limited
USDA puts Garfield County, UT at "Very limited" for septic absorption fields, the dominant reading across 66.9% of the county's soil. Practically, that rules out a simple gravity system for most of the county - 66.9% of it sits in USDA's most-constrained bucket. For scale: 5,179.556 square miles and 5,290 people call Garfield County home.
Before you rely on this for one lot
Two lots a mile apart in Garfield County can carry different soil, even though they share one countywide rating. The real answer for one lot is still a site-specific perc test, running about $750-$1,850 (typically near $1,300).
Budgeting for a system in Garfield County, UT
Garfield County's soil reading pushes the likely outcome toward an engineered system rather than a conventional one. Conventional systems run $3,000-$8,000 where they pass; where they don't, engineered alternatives (mound or aerobic treatment, whichever the health department requires) run $10,000-$40,000 - budget toward the higher figure until a perc test says otherwise.
Where this sits nationally
Among the 3,058 rated counties on this site, Garfield County, UT ranks 2,567 most-constrained nationally, and 20 of 28 within Utah.
Before you act on this
How this rating is built, and its real limits · Conventional vs. engineered septic systems