Weld County, CO's soil, for a septic absorption field
Very limited
In Weld County, CO, 36.7% of the surveyed land carries a "Very limited" rating for a standard septic drain field. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 36.7% of the county. Weld County, CO is 3,984.963 square miles with a population of 369,745.
What Weld County's reading doesn't cover
USDA's survey covers the whole of Weld County, CO 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 Weld County will actually do.
What a system would cost here
With 36.7% of Weld 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.
Where this sits nationally
Nationally, Weld County, CO is the 2,913-most-constrained of 3,058 rated counties for septic soil. Within Colorado alone it ranks 59 of 63.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems