Trempealeau County, WI: the USDA septic-suitability picture

Very limited

USDA puts Trempealeau County, WI at "Very limited" for septic absorption fields, the dominant reading across 90.9% of the county's soil. Practically, that rules out a simple gravity system for most of the county - 90.9% of it sits in USDA's most-constrained bucket. The county spans 732.966 square miles, home to 30,801 people.

What this number does and doesn't tell you

Trempealeau County's rating is an average across the whole county, not a promise about any one lot inside it. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.

Trempealeau County: conventional vs. engineered cost

90.9% of Trempealeau 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.

Trempealeau County's rank among Wisconsin counties

Among the 3,058 rated counties on this site, Trempealeau County, WI ranks 1,177 most-constrained nationally, and 36 of 72 within Wisconsin.

Before you act on this

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