St. Martin Parish's SSURGO septic rating

Very limited

St. Martin Parish, LA's SSURGO dominant class comes back "Very limited", covering 84.7% of the county. A standard gravity system routinely fails on ground like this; the same share of the county falls in USDA's worst absorption-field bucket outright. The county spans 737.549 square miles, home to 51,218 people.

What this number does and doesn't tell you

St. Martin Parish'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.

St. Martin Parish: conventional vs. engineered cost

84.7% of St. Martin Parish 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.

Where this sits nationally

Among the 3,058 rated counties on this site, St. Martin Parish, LA ranks 1,719 most-constrained nationally, and 36 of 61 within Louisiana.

Before you act on this

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