Plan Check Language Library · Mount Washington
Section 3 of Ordinance 168,707 defines two protected tree categories with specific size thresholds. The categories overlap on some trees and apply separately to others. Section 6.F.4 prohibits relocation or removal of either category without a Project Permit and an expanded set of findings under Section 8.B. “Removal” includes acts that cause the tree to die, not only acts that physically remove it. Knowing which trees on a lot meet which definition is the first step in any Specific Plan project that touches existing landscape.
Native Tree Definition
Section 3 defines a Native Tree in three parts:
“Any single trunk Native plant which measures four inches or more in diameter, four and one-half feet above the ground level at the base of the plant; or any multiple trunk Native plant which measures 12 inches or more in diameter immediately below the lowest branch; or any plant planted pursuant to a permit to relocate or remove trees.”
Ordinance 168,707, Section 3
Three pieces of that definition matter at survey time. First, the tree must be a Native plant — Section 3 defines Native Plants as any species listed in Phillip A. Munz’s A Flora of Southern California, or its successor standard reference adopted by the Director, identified as indigenous to the Los Angeles area. Second, the diameter is measured at four and one-half feet above ground level for single-trunk specimens, but immediately below the lowest branch for multi-trunk specimens. The two measurement points produce different numbers on the same tree. Third, plants held for sale at a licensed nursery and street trees are excluded from the Native Tree category.
Significant Tree Definition
The Significant Tree category is independent of native status:
“Any tree which measures 12 inches or more in diameter at four and one-half feet above the average natural grade at the base of the tree and/or is more than 35 feet in height.”
Ordinance 168,707, Section 3
The “and/or” is doing real work in that sentence. A 14-inch-diameter tree that is 25 feet tall is a Significant Tree. A 6-inch-diameter tree that is 40 feet tall is also a Significant Tree. Either threshold alone — the diameter measurement or the height measurement — satisfies the definition. The tree does not have to be native.
The diameter measurement reference here is “average natural grade at the base of the tree,” not ground level. On a sloped lot the average natural grade may sit several inches above or below the actual ground at the trunk, which can shift the measurement point and change whether a borderline tree meets the threshold.
The Two Categories Overlap
A single tree can fall into both categories at once. A native oak measuring 16 inches in diameter and 38 feet tall is a Native Tree (single-trunk Native plant, more than 4 inches at 4.5 feet) and a Significant Tree (more than 12 inches at 4.5 feet above average natural grade, and more than 35 feet tall). The two categories receive the same protection under Section 6.F.4, but the tree report should identify both classifications because the supporting documentation differs. A non-native specimen that meets only the Significant Tree threshold is protected without any reference to the Munz reference.
What “Removal” Means
Section 6.F.4 expands the working definition of removal beyond the act of cutting down a tree. Removal includes any act that causes a Native or Significant Tree to die, including damage to the root system or other parts by fire, application of toxic substances, operation of equipment or machinery, change to the natural grade by excavation or filling within the dripline, or change to the local drainage pattern, either inside or outside the dripline, that significantly affects the amount of water reaching the tree roots.
The drainage clause is the part owners and other firms most often miss. Grading on a separate part of the lot — or even adjacent to the lot — that diverts surface water away from a Significant Tree on or near the project can constitute removal under the ordinance, because removal is read as effect, not intent. A project that does not touch a tree directly can still trigger the Section 6.F.4 prohibition.
Design 1 Studio is a building design firm based in Pasadena, California. Over a decade serving Los Angeles County with residential and commercial design, including ADUs, hillside projects, multifamily, and historic-district work. Inspector-led methodology focused on producing drawings that anticipate plan check rather than react to it. Specialty work in Mount Washington / Glassell Park Specific Plan navigation. Contact through design1.studio.
Mount Washington Project Review
Trees on a Mount Washington Lot?
Design 1 Studio runs the Section 3 measurements on each tree before the site plan is finalized. The Native Tree count, the Significant Tree count, the trees that fall into both, and the dripline analysis Section 8.B requires — all addressed before the design fights the trees that should not have been fought.