Future Annexation and Municipal Urban Growth Areas

Why Would the City Annex?

Increased stability of revenue sources
Annexation may help stabilize the City’s tax base by bringing areas that already rely on City services into the City’s boundaries, creating a more predictable and sustainable source of revenue to support police, parks, streets, and other services.

New opportunities to encourage commercial activity
By annexing nearby commercial corridors, the City could apply its own zoning, infrastructure planning, and economic development tools to support new businesses, reinvestment, and job growth in a way that complements the existing community.

Ability to influence the look and feel of gateway areas
Annexation allows the City to apply its development standards and design guidelines to key corridors leading into Mill Creek, so that buildings, signs, landscaping, and public spaces reflect the community’s desired character and create a consistent “front porch” to the city.

Opportunity to shape development around a future light rail station
Bringing areas that are near a future light rail station into the City gives the community a greater voice in how those properties grow and change, helping to support transit-oriented development, walkability, housing, and job choices that make the most of the regional investment in light rail.

What areas could the City of Mill Creek potentially annex?

The City of Mill Creek has currently divided the Municipal Urban Growth Area into four subareas to allow for more flexibility when it comes to annexation options. These subareas are Mill Creek South, Mill Creek East, Larch, and Martha Lake. (See map for area outlines)

What is a Municipal Urban Growth Area (MUGA)?

A Municipal Urban Growth Area (MUGA) is the portion of the Urban Growth Area that a city is expected to eventually annex and serve. It identifies where a city will focus future urban development, infrastructure, and services, ensuring growth occurs in areas planned for urban levels of housing, jobs, and public facilities.

Who determines the MUGA?

The County designates UGAs in accordance with RCW 36.70A.110. According to RCW 36.70A.100, the designation of UGAs must be coordinated between the county and cities.

What is the purpose of a MUGA?

The Washington State Growth Management Act requires Washington communities to direct growth into designated Urban Growth Areas (UGAs) where urban services can support it, while preserving rural and resource lands for non‑urban uses. Learn about the Growth Management Act here.

Map of the Mill Creek Municipal Urban Growth Areas, showing a map highlighting 4 colored sections around the west, southwest, southeast, and east sides of Mill Creek, named Martha Lake, Larch, South, and East respectively.
Potential Mill Creek Annexation Subarea Map

Timeline & City Council Discussions

  • February 24, 2026 - Rob Fenty, 1961 Consulting, led Council and staff in the Strategic Planning Retreat, providing Council the opportunity to discuss pros and cons of two of the four Urban Growth Areas (UGAs), Martha Lake and Larch, and facilitated Council’s prioritization of the four potential annexation options. Watch the video online here. 
  • February 10, 2026 - Rob Fenty, 1961 Consulting, led Council and staff in the Strategic Planning Retreat, developing a framework to use when considering potential annexation areas and providing Council the opportunity to discuss pros and cons of two of the four Urban Growth Areas (UGAs), Mill Creek East and Mill Creek South. Sarah Emmans, SME Consulting, provided additional information to Council about the UGAs.  Watch the video online here. 
  • February 03, 2026 - Deputy City Manager Brock and consultant Sarah Emmans of SME Consulting LLC led a discussion about the Annexation Feasibility Study findings.  Watch the video online here. 
  • December 09, 2025 - 1961 Consulting Partner Rob Fenty led a Study Session on the upcoming 2026 City Council Strategic Retreat, which will focus on the topic of potential annexation.  Watch the video online here. 
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