Sanilac County's SSURGO septic rating
Very limited
USDA puts Sanilac County, MI at "Very limited" for septic absorption fields, the dominant reading across 88.1% of the county's soil. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 88.1% of Sanilac County's land. For scale: 962.571 square miles and 40,293 people call Sanilac County home.
Before you rely on this for one lot
Two lots a mile apart in Sanilac County can carry different soil, even though they share one countywide rating. The real answer for one lot is still a site-specific perc test, running about $750-$1,850 (typically near $1,300).
Budgeting for a system in Sanilac County, MI
Sanilac County's soil reading pushes the likely outcome toward an engineered system rather than a conventional one. 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, Sanilac County, MI ranks 1,459 most-constrained nationally, and 67 of 83 within Michigan.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems