Septic soil in Todd County, SD, by the numbers
Very limited
In Todd County, SD, 91.7% of the surveyed land carries a "Very limited" rating for a standard septic drain field. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 91.7% of Todd County's land. Todd County, SD is 1,388.593 square miles with a population of 9,172.
What Todd County's reading doesn't cover
Todd County's rating is an average across the whole county, not a promise about any one lot inside it. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Todd County will actually do.
What a system would cost here
With 91.7% of Todd 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 Todd County, SD compares
Nationally, Todd County, SD is the 1,086-most-constrained of 3,058 rated counties for septic soil. Within South Dakota alone it ranks 20 of 66.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems