Sullivan County's SSURGO septic rating
Very limited
Sullivan County, NY: USDA's soil survey calls 93.6% of the county "Very limited" for a septic leach field. A standard gravity system routinely fails on ground like this; the same share of the county falls in USDA's worst absorption-field bucket outright. The county spans 968.145 square miles, home to 80,450 people.
What this number does and doesn't tell you
Sullivan County's rating is an average across the whole county, not a promise about any one lot inside it. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.
Sullivan County: conventional vs. engineered cost
93.6% of Sullivan 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, Sullivan County, NY ranks 846 most-constrained nationally, and 21 of 61 within New York.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems