Septic soil in Sioux County, ND, by the numbers

Very limited

In Sioux County, ND, 80% of the surveyed land carries a "Very limited" rating for a standard septic drain field. That reading means a conventional system is a poor bet here - 80% of Sioux County lands in the strictest "very limited" bucket USDA uses. Sioux County covers 1,094.052 square miles and counts 3,713 residents.

This is a county figure, not a parcel figure

USDA's survey covers the whole of Sioux County, ND 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 Sioux County.

System cost, conventional vs. engineered

Given Sioux 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, Sioux County, ND is the 2,047-most-constrained of 3,058 rated counties for septic soil. Within North Dakota alone it ranks 19 of 53.

Further reading

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