Written by Zachary McCurry, ISA Certified Arborist (Cert. #PN-10373A). Mountlake Terrace adopted a substantial update to its tree regulations in late 2023, its first major revision since 1995. The rules aren’t one single “get a permit to cut down a tree” ordinance — they’re really three separate sets of rules that apply in different situations depending on what you’re doing and where the tree is. Here’s how they actually work.

Three Different Rulebooks, Not One

• Critical areas code (MTMC Chapter 16.15) — applies if the tree is within a stream, wetland, steep-slope, or shoreline buffer, regardless of whether you’re building anything.
• Site development / tree retention code (MTMC Chapter 19.130, Article IV) — applies when a tree is removed as part of a development project: new construction, additions, subdivisions, or anything requiring a building or clearing-and-grading permit.
• Heritage tree program (MTMC § 16.30.070) — a voluntary designation for large, distinctive trees over 36 inches in diameter, on public or private property. A tree isn’t protected as “heritage” just because it’s big; it has to go through a formal application and designation process first.

Removing an Ordinary Tree From Your Yard

If you own a typical residential lot in Mountlake Terrace, aren’t doing any construction, and the tree isn’t in a critical area buffer or formally designated as a heritage tree, we did not find a standalone city permit requirement in the current code for removing that tree. That’s different from cities like Seattle, which require a permit for most significant tree removals citywide. Mountlake Terrace’s tree code is instead concentrated on critical areas, heritage trees, and development activity — not routine homeowner removals on already-developed lots.

That said, the city has a lot of creek corridors (Terrace Creek, Hall Creek, McAleer Creek) and shares Lake Ballinger with Edmonds and Lynnwood, so more properties sit inside a critical area buffer than owners often expect. It’s always worth confirming with the city’s Community and Economic Development Department, or having an arborist check, before assuming a tree is unregulated.

If the Tree Is Near a Stream, Wetland, or Steep Slope

This is where Mountlake Terrace’s rules get strict. Under MTMC § 16.15.115, removing or topping a healthy significant tree inside a critical area or its buffer generally is not permitted at all — there’s no simple permit path, it’s presumptively prohibited.

Hazard trees are treated differently:

• Imminent hazards (actively failing, immediate danger) can be removed under the city’s emergency provisions, with notification to the city within 30 working days.
• Non-imminent hazards (suspected rot, disease, storm-damaged limbs) require a tree evaluation report from a qualified arborist and approval from the city’s Director before removal. Pruning or crown thinning is tried first where it can resolve the hazard; converting the tree to a wildlife snag is prioritized over full removal.

Trees removed in a critical area or buffer must be replaced: two replacement trees for each tree removed at 7 inches DBH or less, four replacement trees for each tree removed at 8 inches DBH or more. A $781-per-tree fee-in-lieu is available if a qualified professional determines that full on-site replacement would harm the critical area.

If You’re Building or Developing

Tree rules under MTMC § 19.130.140 through .199 kick in when a “significant tree” — six inches or more in trunk diameter for deciduous trees, or at least seven feet tall for conifers — would be removed as part of a development project (new construction, additions, subdivision, clearing and grading).

The core requirement: at least 25 percent of the viable significant trees on the site must be retained. If that threshold is met, no further tree action is required. If it can’t be met, the difference has to be made up through some combination of additional retention, on-site replacement planting, or a fee-in-lieu payment:

• 6″–12″ DBH tree removed: 3 replacement trees
• 12″–24″ DBH tree removed: 5 replacement trees
• 24″–48″ DBH tree removed: 7 replacement trees
• Over 48″ DBH tree removed: 10 replacement trees

Fee-in-lieu is $781 per required tree, paid into the city’s tree fund before permits are issued (waived for qualifying affordable housing projects). A qualified arborist has to inventory the site’s trees before any clearing or building permits are issued, and trees marked for retention have to be protected with fencing and root-zone protection for the life of the project.

Heritage Trees

Heritage tree status is reserved for viable trees over 36 inches DBH with distinctive size, shape, species, historical significance, or age. On private property, only the owner can apply, and the application requires an arborist report plus photos and a site map. The Tree Board reviews applications and makes a recommendation; the Planning Director makes the final call. Once designated, a heritage tree can generally only be removed if retaining it would make reasonable use of the property impractical, it conflicts with planned improvements, or it becomes hazardous. Notably, new heritage tree designations aren’t allowed on private property within the Town Center zone.

Penalties for Unauthorized Removal

Mountlake Terrace’s civil penalties are steep enough to change the math on skipping the process: fines are assessed at $1,500 per inch of trunk diameter for a tree removed or damaged in violation of the code, with a minimum $10,000 fine per tree if the diameter can’t otherwise be established. Both the property owner and the contractor doing the work can be held liable, fines are due within 30 days, and unpaid fines can result in a property lien.

Who Can Do the Assessment

Mountlake Terrace’s code defines a “qualified arborist” as someone holding at least one of the following credentials: ISA Certified Arborist, ISA Tree Risk Assessment Qualification (TRAQ), American Society of Consulting Arborists Registered Consulting Arborist, Society of American Foresters Certified Forester, or ISA Board Certified Master Arborist. Hazard tree risk assessments specifically require the TRAQ credential or its equivalent.

The Bottom Line

Before removing any tree in Mountlake Terrace, it’s worth a quick check: is it near a creek, wetland, or slope? Is it part of a construction project? Has it been designated a heritage tree? If the answer to all three is no, a routine removal is usually straightforward. If the answer to any of them is yes, get an arborist assessment first — it’s far cheaper than a civil penalty.

Emerald Arbor Care serves homeowners and property managers throughout Mountlake Terrace and the greater Puget Sound region. Call (206) 558-2814 for a free estimate, or to have us check whether a tree on your property falls under any of these rules before you schedule work.

This post is general information based on Mountlake Terrace Municipal Code Chapters 16.15, 16.30, and 19.130 as of July 2026, and is not legal advice. Always confirm current requirements with the City of Mountlake Terrace Community and Economic Development Department before removing a tree.