Mill Valley Tree Removal, Trimming & Arborist Services

Mill Valley's heritage tree rules (Chapter 20.67)

Chapter 20.67 of the Mill Valley Municipal Code governs trees on privately owned property. Heritage status is set by trunk circumference, not diameter, and the threshold depends on species:

• Tanbark oak (tanoak): 65 inches in circumference
• Oaks and madrone: 75 inches
• Coast redwood: 95 inches

Removing a heritage tree needs a permit. The code also catches cumulative clearing: removing four or more trees over 19 inches in circumference within 12 months on a developed parcel requires a permit even if none of them is a heritage tree. For a tree that is an immediate hazard, the code provides an emergency permit path, so a split redwood leader or an oak leaning onto the house does not have to wait for the normal review.

A tape measure tells you a lot. Wrap it around the trunk and compare the number to the list above before you call; if you are close, an arborist can measure and document it the way the city expects. Many applications go more smoothly with an arborist report that describes the tree's condition, the reason for removal, and any replacement planting.

Redwood canyons, tanoaks, and Sudden Oak Death

Cascade Canyon, Blithedale Canyon, and the streets climbing from Old Mill Park are shaded by second-growth coast redwoods, with tanoak, bay, coast live oak, and madrone mixed in on the drier slopes. Homes from the early 1900s through the mid-century sit on narrow benches between those trees, and a lot of them are reached only by public steps and lanes.

• Redwoods rarely fail outright, but they drop heavy limbs, lift foundations and walkways, and crowd sewer laterals. Thinning and deadwood removal are often a better fit than removal, and removal of a 95-inch redwood needs a permit.
• Tanoaks are highly susceptible to Sudden Oak Death. UC Cooperative Extension advises removing dead oaks and tanoaks when they pose fire or fall risk, and dead tanoaks dry out fast.
• Bays grow multi-stemmed and heavy, and they sometimes split in winter storms.

Step-access lots change how the work is done. Wood often has to be lowered in sections, carried or rigged out, or picked with crane tree removal from the street. A good estimate spells out how debris leaves the property.

Southern Marin Fire and defensible space

Mill Valley was annexed into the Southern Marin Fire Protection District on July 1, 2023, so fire prevention in the city now runs through Southern Marin Fire. The district carries out defensible space and home hardening evaluations under the Marin Wildfire Prevention Authority program funded by Measure C, working through Mill Valley by zone. Cascade Canyon was one of the neighborhoods evaluated in 2024.

Across Marin, local agencies evaluate about a third of residential parcels each year, so a home is typically seen about every three years and gets a Wildfire Risk Report. In the canyons the tree items are predictable: redwood and bay limbs over the roof, dead branches, dense lower limbs, and dead tanoaks near the house. Fire clearance and heritage protection can pull in different directions, so if a required item involves a heritage-size tree, talk to the city before cutting.

Homestead Valley, Tam Valley, and Strawberry

Homestead Valley, Tamalpais Valley, Almonte, and Strawberry share Mill Valley addresses but are unincorporated, so Chapter 20.67 does not apply there. Tree removals in those neighborhoods fall under Marin County's own tree rules in Development Code Chapter 22.62, which use different thresholds. Ask the county planning division before removing a large native tree, and do not assume the city rules carry over.