Septic soil in Stephens County, GA, by the numbers
Very limited
Soil across 50.5% of Stephens County, GA rates "Very limited" in USDA's septic-absorption-field interpretation. Practically, that rules out a simple gravity system for most of the county - 50.5% of it sits in USDA's most-constrained bucket. Stephens County, GA is 178.862 square miles with a population of 27,498.
What Stephens County's reading doesn't cover
Two lots a mile apart in Stephens 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 Stephens County will actually do.
What a system would cost here
With 50.5% of Stephens 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.
Where this sits nationally
Nationally, Stephens County, GA is the 2,873-most-constrained of 3,058 rated counties for septic soil. Within Georgia alone it ranks 103 of 159.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems