Clinton County's SSURGO septic rating
Very limited
Clinton County, MI's SSURGO dominant class comes back "Very limited", covering 97.2% of the county. That reading means a conventional system is a poor bet here - 97.2% of Clinton County lands in the strictest "very limited" bucket USDA uses. The county spans 567.349 square miles, home to 80,050 people.
What this number does and doesn't tell you
Two lots a mile apart in Clinton 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.
Clinton County: conventional vs. engineered cost
97.2% of Clinton 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, Clinton County, MI ranks 348 most-constrained nationally, and 11 of 83 within Michigan.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems