Brown County, OH: the USDA septic-suitability picture
Very limited
Brown County, OH: USDA's soil survey calls 98.6% of the county "Very limited" for a septic leach field. That reading means a conventional system is a poor bet here - 98.6% of Brown County lands in the strictest "very limited" bucket USDA uses. The county spans 489.551 square miles, home to 44,292 people.
What this number does and doesn't tell you
USDA's survey covers the whole of Brown County, OH at once, not any single address. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Brown County: conventional vs. engineered cost
98.6% of Brown County carrying a "Very limited" reading changes the realistic budget here. 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, Brown County, OH ranks 148 most-constrained nationally, and 17 of 87 within Ohio.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems