What Marion County, TX's soil rates for a septic system
Very limited
83% of Marion County, TX's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 83% of Marion County's land. Marion County, TX is 380.902 square miles with a population of 9,704.
What Marion County's reading doesn't cover
This is a countywide, area-weighted figure across every soil survey map unit in Marion County, TX - never a reading for one specific parcel. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Marion County will actually do.
What a system would cost here
With 83% of Marion County rating "Very limited", a standard gravity system is not a safe assumption here. The engineered-system range, $10,000-$40,000 (mound or aerobic treatment), is the more realistic number to plan around, against $3,000-$8,000 for a conventional system on the rare lot that passes.
Marion County's rank among Texas counties
Nationally, Marion County, TX is the 1,860-most-constrained of 3,058 rated counties for septic soil. Within Texas alone it ranks 136 of 253.
Further reading
How this rating is built, and its real limits · Conventional vs. engineered septic systems