The Mill Creek Planning Commission voted to recommend to city council a set of amendments to the city's Critical Areas Ordinance that staff said modernize protections for wetlands, streams, habitat and other critical areas and align the code with best-available science and recent state agency guidance.

Staff context and timeline: Speaker 4, the staff presenter, said the city hired a consultant to prepare a best-available-science review and gap analysis and that staff had notified state agencies in October and received comments from the Department of Fish and Wildlife (WDFW) and Department of Natural Resources. Staff noted the state compliance deadline is Dec. 31, 2025, and said final adoption is most likely at the first council meeting in January.

Major changes: The package includes several substantive updates:

- Riparian Management Zones (RMZs): Instead of fixed stream-buffer widths, the amendments adopt RMZs sized by site-potential tree height (a long-term dominant-tree-height metric). Staff explained this will set RMZ widths that in many cases are larger for smaller streams and may be smaller for North Creek where wetland buffers already provide greater protection. Staff said the city will publish an official WDFW-based map and allow applicants to commission their own studies if they disagree.

- Wetlands and buffers: Staff proposed a simplified buffer table that accounts for wetland category, habitat score and land-use intensity. Buffer widths in the new table range by category and could vary from tens to a few hundred feet depending on habitat score and impact minimization measures; the code allows up to a 25% reduction for low-impact land uses and requires post-impact monitoring and demonstration of no net loss of function for impacted areas.

- Nonconforming uses and subdivision clarity: The amendments clarify how legally established nonconforming uses and structures may be maintained, altered and rebuilt without losing their status, and they permit redevelopment within existing impervious footprints. During discussion commissioners asked whether the new subdivision prohibition for land wholly within a buffer unintentionally blocked redevelopment; the commission agreed to add clarifying language permitting subdivision of nonconforming uses when appropriate and included that amendment in the recommendation to council.

- Trails and mitigation: Creation of new trails was changed from an exempt activity to one requiring mitigation appropriate to the impact (examples: boardwalks across wetlands, native-vegetation replanting). Staff said most existing trails built before the rule changes may remain but that undocumented trails the city takes over could trigger mitigation obligations or mitigation-bank credits.

- Reasonable-use exceptions and monitoring: The code defines reasonable-use exceptions for encumbered parcels (e.g., allowing up to 2,500 sq ft for a single-family footprint, with a process to request more based on neighborhood analysis). Mitigation-monitoring requirements were reduced to reflect best-available science (fewer reports over multiple years than the prior rule).

Agency input and support: Staff said a meeting with WDFW led to minor edits (including renaming "functionally disconnected buffer" to "functionally disconnected area" so the concept applies to both buffers and RMZs) and that WDFW provided a letter of support earlier the same day.

Commission action: Speaker 5 moved to approve the planning commission resolution recommending the ordinance changes; commissioners discussed and voted to adopt an amendment clarifying that nonconforming uses may be subdivided for redevelopment. The amended recommendation was approved by voice vote and will be forwarded to city council.

Ending: Staff said final adoption is likely early January after council review and that materials (including the WDFW-based RMZ map) will be posted to the city website. The Planning Commission closed the public hearing and moved the recommendation to council with the clarifying amendment.