Jefferson County, MT: the USDA septic-suitability picture

Very limited

Jefferson County, MT: USDA's soil survey calls 67.7% of the county "Very limited" for a septic leach field. That reading means a conventional system is a poor bet here - 67.7% of Jefferson County lands in the strictest "very limited" bucket USDA uses. The county spans 1,656.997 square miles, home to 13,304 people.

What this number does and doesn't tell you

Two lots a mile apart in Jefferson County can carry different soil, even though they share one countywide rating. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.

Jefferson County: conventional vs. engineered cost

67.7% of Jefferson 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.

How Jefferson County, MT compares

Among the 3,058 rated counties on this site, Jefferson County, MT ranks 2,540 most-constrained nationally, and 50 of 54 within Montana.

Further reading

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