Mountlake Terrace staff proposes stricter critical-area rules; recommends moderate increase to stream buffers

Senior Planner Sarah Pizzo presented a draft update to Mountlake Terrace’s critical area ordinance to the Planning Commission on Oct. 13, urging adoption by the end of the year to comply with the state Growth Management Act and updated state guidance.

The draft would expand the ordinance’s reach and raise protections for wetlands, streams, geohazard areas, frequently flooded areas and critical aquifer recharge areas (CARAs). Pizzo said the city must adopt changes before year’s end and that the update aligns the code with the city’s comprehensive plan environmental element and best available science.

Pizzo said the proposal increases the distance to which regulations apply for streams, wetlands and water bodies from a previous 200-foot standard to 300 feet in some cases and adds coverage within channel migration zones or ordinary high water marks where shoreline rules do not already apply. The draft also adds regulation of areas within 200 feet of mapped critical aquifer recharge areas.

On wetlands, the draft would require vegetated buffers planted with native species appropriate to the ecoregion and increase standard buffer widths by about 20–25 feet for most wetland categories (excluding highly disturbed Category 4 wetlands). Where slopes exceed 30 percent, wetland buffers would increase by 50 percent, per the draft and Ecology recommendations.

For streams, staff presented four buffer options and recommended what staff called the moderate change: raising fish-bearing (Type F) buffers to 150 feet and non-fish perennial/seasonal streams to 100 feet, while reducing the building setback to 10 feet to lessen development impacts. Pizzo said this recommendation meets Department of Fish and Wildlife minimums and that the city received a supporting letter from Fish and Wildlife. Staff noted the change would increase the number of impacted parcels from 223 under current mapping to about 354 under the recommended option.

Pizzo described other changes intended to tighten implementation and monitoring: clarifying exemptions for functionally isolated wetlands and buffers; allowing buffer changes only when there is a demonstrated net ecological gain; explicitly permitting native-vegetation replanting and restoration that results in ecological benefit; removing the blanket prohibition on some removal methods so effective invasive-plant control tools can be used; and requiring replanted areas to be restored within a tightened time frame (Pizzo said the draft tightens the timeline to "within 30" ) and to include post-restoration monitoring.

The draft adds a legal nonconforming section that would allow structures and legal uses in existence on the ordinance’s effective date (or vested applications filed before adoption) to be maintained or repaired without increasing footprint or impervious area; abandoned structures would forfeit nonconforming status after six continuous months. The draft also clarifies that compensatory mitigation is not allowed for CARAs and requires hydrogeologic reports prepared by a geologist licensed in hydrogeology for CARA-related development proposals.

Commissioners asked for clearer, parcel-level mapping and impact analysis. Commissioners Stinson and others asked staff to show maps that overlay proposed buffer options with zoning and current impervious cover so the commission could assess effects on development capacity—particularly in Towne Center, the Gateway mixed-use area and known redevelopment sites. Pizzo said the city’s GIS specialist, Paul, and outside consultant FACET had produced parcel analyses and that staff would include maps and parcel impact details at the next meeting.

Commissioners also asked how the draft would affect redevelopable neighborhood-center parcels and industrial properties near mapped wellhead protection. Pizzo said much of Mountlake Terrace’s critical areas are in parks and that nonconforming code provisions mean many already-developed parcels will face limits on new encroachment but not forcible removal of existing improvements.

No formal action was taken; the commission’s discussion focused on policy choices and implementation details. The commission briefly approved the Sept. 22, 2025 meeting minutes at the start of the session and there were no in-person or written public comments for this agenda item.

Staff next steps include returning with maps that show parcel-level impacts for the buffer options, an overlay of zoning/comp plan designations with critical-area mapping, and a breakdown of how much of affected acreage is already covered by impervious surface or existing development.

Byline: Mountlake Terrace Planning Commission reporting; staff presentation by Senior Planner Sarah Pizzo.