Jefferson County, WI's soil, for a septic absorption field

Very limited

Soil across 90.7% of Jefferson 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 90.7% of the county. Jefferson County covers 556.494 square miles and counts 86,245 residents.

This is a county figure, not a parcel figure

This is a countywide, area-weighted figure across every soil survey map unit in Jefferson County, WI - never a reading for one specific parcel. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Jefferson County.

System cost, conventional vs. engineered

Given Jefferson 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.

Where this sits nationally

Nationally, Jefferson County, WI is the 1,194-most-constrained of 3,058 rated counties for septic soil. Within Wisconsin alone it ranks 38 of 72.

Related guides

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