Septic soil in Del Norte County, CA, by the numbers

Very limited

96.4% of Del Norte County, CA's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. 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. Del Norte County, CA is 1,006.202 square miles with a population of 27,009.

What Del Norte County's reading doesn't cover

USDA's survey covers the whole of Del Norte County, CA at once, not any single address. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Del Norte County will actually do.

What a system would cost here

With 96.4% of Del Norte 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.

Del Norte County's rank among California counties

Nationally, Del Norte County, CA is the 469-most-constrained of 3,058 rated counties for septic soil. Within California alone it ranks 7 of 57.

Further reading

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