Milton planners review proposed 'Significant Tree' code to protect canopy, debate thresholds and enforcement

Planning Manager Sollnecker presented PLN 2025-008 at the Planning Commission's Dec. 10 meeting, outlining a new community-forest preservation subsection to be added to the municipal code. Sollnecker said the draft pulls tree protections out of the landscaping chapter and makes them a standalone section covering purpose, definitions, applicability, surveys, retention and replacement. "So that's what I have here on page 7, 8, 9, and 10 is a proposed, community forest preservation subsection" he said, identifying proposed code references and an intent to replace the existing subsection in the code.

Why it matters: commissioners said the update would give Milton stronger, clearer authority to limit indiscriminate clearing as development increases. Sollnecker told the commission the draft would apply to new residential construction (single-family, two-family and ADUs), nonresidential development over 2,500 square feet of disturbance, and existing "underdeveloped" lots 10,000 square feet or larger. The proposal aims to require tree surveys, standardized arborist assessments and replacement plantings when significant trees are removed.

Key proposals and numeric details in the draft: Manager Sollnecker described the proposed definitions and thresholds as follows — significant tree: evergreens with a minimum diameter of 12 inches and deciduous trees with a minimum diameter of 9 inches; exceptional tree: trees 30 inches diameter or greater that are generally to be preserved; a proposed retention target of 35% of significant trees; applicability thresholds of 10,000 sq ft for underdeveloped residential lots and 2,500 sq ft of disturbance for nonresidential expansions. Sollnecker also discussed replacement rules and an in-lieu fee mechanism to fund off-site plantings.

Commissioner debate: Commissioners generally supported a standalone tree chapter but pressed for changes and clarifications. Commissioner Oler praised requiring a "tree risk assessment determined by a certified arborist" and urged a standardized ISA-based assessment and documentary requirements for hazard claims. "Maybe we require a second opinion if it's an exceptional tree," Oler said, arguing that photographic documentation and a template would reduce subjectivity.

Several commissioners questioned the standards for "exceptional" and "significant" trees. Commissioner Zarrow asked whether an "exceptional" tree should be an absolute prohibition on removal, noting potential conflicts with affordable-housing siting where an exceptional tree might stand in the middle of a buildable lot. Sollnecker said staff could include limited allowances or a variance pathway for truly compelling circumstances but emphasized intent to preserve exceptional specimens.

Retention, canopy and measurement issues: The draft's 35% retention target drew criticism and alternative proposals. Commissioner Zarrow recommended increasing the retention requirement to 50% for clarity and effectiveness; other commissioners raised the point that counting the number of trees alone can ignore canopy value and suggested measuring canopy or accumulated diameter as alternatives. Sollnecker said staff will refine options and bring examples for how the rules would operate in practice.

Replacement rules and in-lieu fee: The proposal includes replacement ratios (for example, one larger planted tree versus multiple smaller ones) and an option to pay an in-lieu fee when on-site replacement would conflict with best landscaping practices. Commissioners urged prioritizing on-site replacement, discouraging easy payment options, and ensuring the in-lieu fee reflects canopy loss rather than a flat low fee. Sollnecker said in-lieu payment would only be allowed after a deviation process and that fees would be directed to a city fund used for public plantings or tree purchase programs.

Enforcement and next steps: Commissioners asked for clearer inspection and enforcement language, standards for who can conduct arborist assessments, and guidance so homeowners can understand when a permit is required. Sollnecker agreed to provide a standardized arborist-report template, clarify measurement rules, and circulate revised text in January. He recommended the commission review edits over the month and hold a public hearing in February; commissioners agreed to revisit the draft in February for a public hearing and potential vote.

What remains unresolved: diameter thresholds (some favored lower/higher numbers), whether retention should be numeric count versus canopy-based, how to handle exceptional trees in constrained affordable-housing sites, and precise in-lieu fee formulas and enforcement staffing. Staff will return with edited language and examples to test how the rules would work on sample developments.