Council advances stormwater and floodplain update; new permitting and fees proposed

The Thornton City Council on July 22 gave first reading approval to an ordinance that reorganizes stormwater and floodplain rules, adopts the Mile High Flood District urban storm drainage criteria manual by reference and establishes a stormwater quality permitting system for development disturbances.

Keith Bisbee, the city’s stormwater coordinator, told the council the package extracts stormwater provisions from Chapter 18 and places them in a new Chapter 22 to consolidate technical standards, align enforcement under one group and move stormwater‑related fees into the stormwater enterprise fund. The change is intended to simplify administration and to place technical material (design manuals and specifications) in referenced standards rather than in ordinance text.

The ordinance would require a stormwater quality permit for projects that disturb 1 acre or more, or smaller sites that are part of a larger common plan of development. As part of the permitting approach, staff proposed a bracketed fee schedule tied to disturbed acreage, a $150 administrative fee for annual permit renewals and a structure of escalating reinspection fees ($150, then $300) that can lead to a stop‑work order for repeated noncompliance. Bisbee said the proposal also includes an administrative limit on the acreage of active disturbance (generally 40 acres at a time) to improve compliance and reduce erosion and runoff risks.

Bisbee showed comparative data that put Thornton’s proposed permitting and reinspection fees near the mid‑range of other Colorado municipalities that charge by acreage. He said the fees largely recover costs that were previously embedded in development construction review fees and that the changes reallocate those costs into the stormwater enterprise fund.

Staff recommended adoption of the ordinance on first reading and scheduled a second reading for Aug. 12. Bisbee said the city expects a new MS4 permit from the state in the near term and that updating local stormwater code now will help the city meet forthcoming regulatory expectations.

Council members had no substantive objections during the first reading; the ordinance passed on first reading by unanimous vote. Bisbee said staff will continue stakeholder engagement and noted the Home Builders Association had no substantive objections to the proposed changes.

Ending: The ordinance passed on first reading; second reading is scheduled for Aug. 12. If adopted, the city will begin implementing the permitting process and fee schedule, and staff will publish administrative guidance for permit applicants.