Bellevue holds public hearing on draft 2025 Stormwater Management Program; permit changes could widen retrofit scope

Tanya McFarland, senior engineering technician in Utilities and Water Quality, and Don McWilliams, operations manager in Utilities, presented Bellevue’s draft 2025 Stormwater Management Program (SWMP) plan to the Environmental Services Commission on March 6 and held a public hearing on the draft plan.

McWilliams summarized key changes in the National Pollutant Discharge Elimination System (NPDES) permit issued by the Washington State Department of Ecology in late 2024. He told the commission that Ecology added three major areas of new focus: detailed mapping of tree canopy and stormwater facilities, tightened requirements for stormwater control on new development and redevelopment (lowering some thresholds from about 5,000 square feet to as low as 2,000), and a new retrofit requirement for existing development—referred to in the permit as Stormwater Management for Existing Development (SMED).

On SMED, McWilliams said the permit requires “equivalent treatment to 24.6 acres” and gives two compliance paths: structural retrofits to provide treatment and flow control, or nonstructural measures (enhanced maintenance such as more sweeping and pipe cleaning), but nonstructural credits are limited to up to 25% of the requirement. “Seventy-five percent of this has to be done through the retrofitting,” he said, adding that the city is evaluating mapping and options and that the work could be expensive.

McFarland reviewed the structure of the draft SWMP, which follows the permit’s nine sections and will be finalized after the public comment period and the commission’s recommendations. She said Bellevue’s program inspects a high share of its system relative to the permit minimums: the permit requires screening 12% annually and the city inspects roughly 50% of structures each year. Utilities staff said the city maintains about 25,000 storm structures and inspects more than 12,000 annually.

Under the permit’s business-inspection requirements, Ecology requires annual inspections of 20% of identified businesses; Bellevue’s program covers about 1,500 sites, so the requirement equates to inspecting roughly 300 businesses per year. McFarland said the utilities division will adopt the new Western Washington stormwater maintenance manual (or an equivalent) by June 2027, as required by Ecology.

One resident from Eastgate thanked the commission and asked for greater construction-site oversight in her neighborhood; she said roughly 8 to 10 construction projects are active near her home and requested more surveillance of contractors to prevent stormwater impacts. Commissioners asked staff about interjurisdictional coordination with neighboring cities, and McWilliams said Bellevue participates in regional NPDES coordination groups with Redmond, Kirkland, Renton and others.

The commission opened and then closed the public hearing; commissioners will forward the public comments and the commission’s recommendations to the city’s NPDES coordinator for consideration before the draft plan is finalized. The draft plan is posted on the city website; staff asked for written comments and said they will submit the final SWMP together with the annual compliance report to Ecology.