Septic soil in Garfield County, WA, by the numbers
Very limited
In Garfield County, WA, 88% of the surveyed land carries a "Very limited" rating for a standard septic drain field. Practically, that rules out a simple gravity system for most of the county - 88% of it sits in USDA's most-constrained bucket. Garfield County, WA is 710.835 square miles with a population of 2,404.
What Garfield County's reading doesn't cover
Two lots a mile apart in Garfield County can carry different soil, even though they share one countywide rating. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Garfield County will actually do.
What a system would cost here
With 88% of Garfield 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.
Garfield County's rank among Washington counties
Nationally, Garfield County, WA is the 1,470-most-constrained of 3,058 rated counties for septic soil. Within Washington alone it ranks 27 of 39.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems