Septic soil in Douglas County, OR, by the numbers

Very limited

Soil across 97.5% of Douglas County, OR 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 97.5% of Douglas County's land. Douglas County covers 5,035.755 square miles and counts 112,255 residents.

This is a county figure, not a parcel figure

This is a countywide, area-weighted figure across every soil survey map unit in Douglas County, OR - never a reading for one specific parcel. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Douglas County.

System cost, conventional vs. engineered

Given Douglas 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 Douglas County, OR compares

Nationally, Douglas County, OR is the 315-most-constrained of 3,058 rated counties for septic soil. Within Oregon alone it ranks 5 of 36.

Further reading

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