Committee forwards proposed 2026 stormwater manual and code amendments to council to meet Ecology equivalency

Environmental Services presented proposed revisions to the city's 2026 Stormwater Management Manual (SWMM) and recommended code amendments to achieve equivalency with the Washington State Department of Ecology manual for Western Washington. The committee voted to forward the proposed code amendments to full council for consideration.

Shauna Hansen, stormwater management program coordinator, said the manual governs the municipal separate storm sewer system and related city responsibilities including mapping, maintenance, system expansion and water-quality monitoring. Hansen said the updated manual will be used by staff reviewing redevelopment projects and business inspections and that the updates are needed to meet Ecology permit requirements. "The stormwater management manual...is updated to the equivalent of the Washington State Department of Ecology's stormwater management manual for Western Washington," Hansen said.

Mika Hoffman, the manual editor and project manager, summarized technical changes in the draft: additional low-impact development (LID) practices and treatment requirements for certain redevelopment projects, new BMPs (channelized flow dispersion, infiltration swales, ballasted sidewalks), expanded planting and tree-protection language, and new guidance and restrictions addressing building washings and PCBs. Hoffman said certain roads, large parking areas, fueling stations and light-rail projects will face additional treatment requirements under the Ecology-aligned standards.

Staff described the public and SEPA/CEPA outreach process (first comment period in March, a second comment period and public notice period) and said they will provide user and code-update training to implement the manual. Staff stated the manual is intended to be effective in mid-2026 (the transcript references July 2026); members requested that staff clearly highlight differences between the existing code and the Ecology-aligned manual when the item reaches full council.

A council member moved to forward proposed amendments to Tacoma Municipal Code chapter 12.8D to the full city council for consideration; the motion was seconded and adopted. Staff will include the public comment summary and a comparison of changes in materials sent to the council.

Next steps: staff will transmit the proposed code amendments and the draft manual to the full council and provide training and explanatory materials ahead of council action.