Carroll County, IA: the USDA septic-suitability picture

Very limited

Carroll County, IA's SSURGO dominant class comes back "Very limited", covering 80.9% of the county. A standard gravity system routinely fails on ground like this; the same share of the county falls in USDA's worst absorption-field bucket outright. The county spans 569.453 square miles, home to 20,407 people.

What this number does and doesn't tell you

USDA's survey covers the whole of Carroll County, IA at once, not any single address. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.

Carroll County: conventional vs. engineered cost

80.9% of Carroll 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, Carroll County, IA ranks 1,997 most-constrained nationally, and 84 of 99 within Iowa.

Further reading

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