What Roseau County, MN's soil rates for a septic system
Very limited
In Roseau County, MN, 99.2% 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 - 99.2% of Roseau County lands in the strictest "very limited" bucket USDA uses. Roseau County, MN is 1,671.739 square miles with a population of 15,265.
What Roseau County's reading doesn't cover
USDA's survey covers the whole of Roseau County, MN at once, not any single address. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Roseau County will actually do.
What a system would cost here
With 99.2% of Roseau County rating "Very limited", a standard gravity system is not a safe assumption here. 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, Roseau County, MN is the 67-most-constrained of 3,058 rated counties for septic soil. Within Minnesota alone it ranks 3 of 86.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems