Marshall County's SSURGO septic rating

Very limited

USDA puts Marshall County, IL at "Very limited" for septic absorption fields, the dominant reading across 82.9% of the county's soil. Practically, that rules out a simple gravity system for most of the county - 82.9% of it sits in USDA's most-constrained bucket. For scale: 386.822 square miles and 11,552 people call Marshall County home.

Before you rely on this for one lot

Nothing about Marshall County, IL's SSURGO figure applies to a specific address - it's a county-wide average. 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 Marshall County, IL

Marshall 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.

How Marshall County, IL compares

Among the 3,058 rated counties on this site, Marshall County, IL ranks 1,871 most-constrained nationally, and 63 of 101 within Illinois.

Related guides

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