What Stevens County, WA's soil rates for a septic system
Very limited
Soil across 94.5% of Stevens County, WA rates "Very limited" in USDA's septic-absorption-field interpretation. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 94.5% of Stevens County's land. Stevens County, WA is 2,477.103 square miles with a population of 49,015.
What Stevens County's reading doesn't cover
Nothing about Stevens County, WA's SSURGO figure applies to a specific address - it's a county-wide average. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Stevens County will actually do.
What a system would cost here
With 94.5% of Stevens 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, Stevens County, WA is the 712-most-constrained of 3,058 rated counties for septic soil. Within Washington alone it ranks 13 of 39.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems