Minnehaha County, SD's soil, for a septic absorption field

Very limited

Soil across 74.2% of Minnehaha County, SD 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 74.2% of the county. Minnehaha County covers 806.86 square miles and counts 208,639 residents.

This is a county figure, not a parcel figure

USDA's survey covers the whole of Minnehaha County, SD 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 Minnehaha County.

System cost, conventional vs. engineered

Given Minnehaha 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, Minnehaha County, SD is the 2,323-most-constrained of 3,058 rated counties for septic soil. Within South Dakota alone it ranks 53 of 66.

Before you act on this

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