Lafourche Parish, LA: the USDA septic-suitability picture

Very limited

Lafourche Parish, LA: USDA's soil survey calls 71.3% of the county "Very limited" for a septic leach field. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 71.3% of the county. For scale: 1,069.696 square miles and 95,342 people call Lafourche Parish home.

Before you rely on this for one lot

Lafourche Parish's rating is an average across the whole county, not a promise about any one lot inside it. 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 Lafourche Parish, LA

Lafourche Parish'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, Lafourche Parish, LA ranks 2,427 most-constrained nationally, and 56 of 61 within Louisiana.

Further reading

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