Clark County's SSURGO septic rating

Very limited

USDA puts Clark County, WA at "Very limited" for septic absorption fields, the dominant reading across 84.3% of the county's soil. 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. For scale: 628.509 square miles and 527,269 people call Clark County home.

Before you rely on this for one lot

This is a countywide, area-weighted figure across every soil survey map unit in Clark County, WA - never a reading for one specific parcel. 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 Clark County, WA

Clark County'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.

How Clark County, WA compares

Among the 3,058 rated counties on this site, Clark County, WA ranks 1,751 most-constrained nationally, and 29 of 39 within Washington.

Before you act on this

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