Septic soil in Mahnomen County, MN, by the numbers

Very limited

In Mahnomen County, MN, 83.7% of the surveyed land carries a "Very limited" rating for a standard septic drain field. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 83.7% of the county. Mahnomen County covers 557.867 square miles and counts 5,296 residents.

This is a county figure, not a parcel figure

Two lots a mile apart in Mahnomen 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 Mahnomen County.

System cost, conventional vs. engineered

Given Mahnomen 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 Mahnomen County, MN compares

Nationally, Mahnomen County, MN is the 1,811-most-constrained of 3,058 rated counties for septic soil. Within Minnesota alone it ranks 65 of 86.

Before you act on this

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