Linn County's SSURGO septic rating

Very limited

USDA puts Linn County, IA at "Very limited" for septic absorption fields, the dominant reading across 89.8% of the county's soil. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 89.8% of the county. The county spans 717.013 square miles, home to 231,762 people.

What this number does and doesn't tell you

Two lots a mile apart in Linn County can carry different soil, even though they share one countywide rating. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.

Linn County: conventional vs. engineered cost

89.8% of Linn County carrying a "Very limited" reading changes the realistic budget here. Conventional systems run $3,000-$8,000 where they pass; where they don't, engineered alternatives (mound or aerobic treatment, whichever the health department requires) run $10,000-$40,000 - budget toward the higher figure until a perc test says otherwise.

Where this sits nationally

Among the 3,058 rated counties on this site, Linn County, IA ranks 1,286 most-constrained nationally, and 74 of 99 within Iowa.

Before you act on this

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