Black Hawk County's SSURGO septic rating
Very limited
USDA puts Black Hawk County, IA at "Very limited" for septic absorption fields, the dominant reading across 91.2% of the county's soil. That reading means a conventional system is a poor bet here - 91.2% of Black Hawk County lands in the strictest "very limited" bucket USDA uses. The county spans 565.773 square miles, home to 132,348 people.
What this number does and doesn't tell you
USDA's survey covers the whole of Black Hawk 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.
Black Hawk County: conventional vs. engineered cost
91.2% of Black Hawk 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.
How Black Hawk County, IA compares
Among the 3,058 rated counties on this site, Black Hawk County, IA ranks 1,146 most-constrained nationally, and 70 of 99 within Iowa.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems