Weld County, CO Environmental Rules: Erosion Control (2026)

Sec. 8-12-30 makes it unlawful to surface disturb, grade, construct or excavate over one acre of nonexempted ground in unincorporated Weld County without a Grading Permit, and the disturbed-area threshold is cumulative: contiguous subdivision lots under common ownership and connected project segments that together exceed one acre all count toward the limit, so a developer cannot dodge the permit by phasing a project into smaller pieces. A handful of activities are exempt, including tillage of agricultural land, trenching for underground pipelines, and maintenance of existing ditches, lakes and reservoirs, but the exemption disappears if the parcel sits inside a designated Municipal Separate Storm Sewer System (MS4) area.

Inside the MS4 area, Sec. 8-9-80 layers on a separate requirement: before any land-disturbing activity of an acre or more, the owner must submit and get accepted a Sediment and Erosion Control Plan identifying every temporary control measure, structural and non-structural, used from initial disturbance through final stabilization, plus a Stormwater Pollution Prevention Plan covering vehicle tracking, outdoor material storage, concrete washing and other pollutant sources. The Department of Public Works then runs routine inspections at least every 45 days while work is active, compliance inspections within 14 days of a recorded violation, and inactive-site inspections every 90 days until the site reaches final stabilization and the permit is released.