Septic soil in Crittenden County, KY, by the numbers
Very limited
Soil across 90.8% of Crittenden County, KY rates "Very limited" in USDA's septic-absorption-field interpretation. That reading means a conventional system is a poor bet here - 90.8% of Crittenden County lands in the strictest "very limited" bucket USDA uses. Crittenden County, KY is 359.566 square miles with a population of 8,982.
What Crittenden County's reading doesn't cover
USDA's survey covers the whole of Crittenden County, KY at once, not any single address. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Crittenden County will actually do.
What a system would cost here
With 90.8% of Crittenden 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, Crittenden County, KY is the 1,189-most-constrained of 3,058 rated counties for septic soil. Within Kentucky alone it ranks 60 of 119.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems