Septic soil in Allegan County, MI, by the numbers

Very limited

Soil across 94% of Allegan County, MI rates "Very limited" in USDA's septic-absorption-field interpretation. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 94% of Allegan County's land. Allegan County covers 825.43 square miles and counts 122,429 residents.

This is a county figure, not a parcel figure

Nothing about Allegan County, MI's SSURGO figure applies to a specific address - it's a county-wide average. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Allegan County.

System cost, conventional vs. engineered

Given Allegan County's rating, plan for the engineered-system range rather than the conventional one. The engineered-system range, $10,000-$40,000 (mound or aerobic treatment), is the more realistic number to plan around, against $3,000-$8,000 for a conventional system on the rare lot that passes.

Where this sits nationally

Nationally, Allegan County, MI is the 782-most-constrained of 3,058 rated counties for septic soil. Within Michigan alone it ranks 38 of 83.

Related guides

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