St. Clair County, MI: the USDA septic-suitability picture

Very limited

USDA puts St. Clair County, MI at "Very limited" for septic absorption fields, the dominant reading across 95.4% of the county's soil. That reading means a conventional system is a poor bet here - 95.4% of St. Clair County lands in the strictest "very limited" bucket USDA uses. The county spans 721.522 square miles, home to 160,308 people.

What this number does and doesn't tell you

USDA's survey covers the whole of St. Clair County, MI 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.

St. Clair County: conventional vs. engineered cost

95.4% of St. Clair 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, St. Clair County, MI ranks 606 most-constrained nationally, and 29 of 83 within Michigan.

Before you act on this

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