Audubon County, IA's soil, for a septic absorption field

Very limited

In Audubon County, IA, 99% 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 99% of Audubon County's land. Audubon County covers 442.96 square miles and counts 5,562 residents.

This is a county figure, not a parcel figure

USDA's survey covers the whole of Audubon County, IA at once, not any single address. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Audubon County.

System cost, conventional vs. engineered

Given Audubon 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, Audubon County, IA is the 104-most-constrained of 3,058 rated counties for septic soil. Within Iowa alone it ranks 8 of 99.

Further reading

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