Septic soil in Sauk County, WI, by the numbers

Very limited

Soil across 94.3% of Sauk County, WI rates "Very limited" in USDA's septic-absorption-field interpretation. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 94.3% of the county. Sauk County covers 831.587 square miles and counts 66,486 residents.

This is a county figure, not a parcel figure

Two lots a mile apart in Sauk County can carry different soil, even though they share one countywide rating. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Sauk County.

System cost, conventional vs. engineered

Given Sauk County's rating, plan for the engineered-system range rather than the conventional one. 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 Sauk County, WI compares

Nationally, Sauk County, WI is the 741-most-constrained of 3,058 rated counties for septic soil. Within Wisconsin alone it ranks 17 of 72.

Further reading

How this rating is built, and its real limits · Conventional vs. engineered septic systems