Septic soil in Gregory County, SD, by the numbers
Very limited
In Gregory County, SD, 91.8% of the surveyed land carries a "Very limited" rating for a standard septic drain field. That reading means a conventional system is a poor bet here - 91.8% of Gregory County lands in the strictest "very limited" bucket USDA uses. Gregory County, SD is 1,014.95 square miles with a population of 4,110.
What Gregory County's reading doesn't cover
This is a countywide, area-weighted figure across every soil survey map unit in Gregory County, SD - never a reading for one specific parcel. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Gregory County will actually do.
What a system would cost here
With 91.8% of Gregory 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.
How Gregory County, SD compares
Nationally, Gregory County, SD is the 1,070-most-constrained of 3,058 rated counties for septic soil. Within South Dakota alone it ranks 19 of 66.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems