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Chapter 11.80 Definitions and Measurements

City Code Chapter

11.80.010 Defining Words.

  1. Words used in the tree code have their normal dictionary meaning unless they are listed in Section 11.80.020 below. Words listed in Section 11.80.020 have the specific meaning stated, unless the context clearly indicates another meaning.

11.80.020 Definitions and Measurements.

(Amended by Ordinances 188278, 189078 and 191030, effective November 11, 2022.)

  1. A.  Information about the use of terms in the tree code is contained in Section 11.10.030.
  2. B.  The definition of words with specific meaning in the tree code are as follows:
    1. 1.  "Appeals Board" is the Urban Forestry Appeals Board. The duties and composition are in Section 11.20.030.
    2. 2.  "Arboriculture" refers to the horticultural focus on the study and care of trees and other woody plants.
    3. 3.  "Arborist" means a professional listed as a certified arborist by the International Society of Arboriculture or a consulting arborist registered with the American Society of Consulting Arborists.
    4. 4.  "Attached Structure" means a structure attached to a building.
    5. 5.  "BDS Director" is the Director of the Bureau of Development Services or the BDS Director's designee. The duties of the BDS Director are in Section 11.10.010.
    6. 6.  "Building" means a structure that has a roof, is enclosed on at least 50 percent of the area of its sides and required a development permit prior to construction.
    7. 7.  "Building Coverage" has the same meaning as in Title 33 Planning and Zoning.
    8. 8.  "Business Hours" means 7:30 am to 5 pm, during working days.
    9. 9.  "City" is the City of Portland.
    10. 10.  "City Forester" is the Manager of Urban Forestry, or the Manager’s designee. The duties of the City Forester are in Section 11.10.010.
    11. 11.  "Commission" means the Urban Forestry Commission, also referred to as the UFC. The duties and composition are in Section 11.20.020.
    12. 12.  “Construction Staging Area” means a designated area for the storage of equipment and vehicles, stockpiles, waste bins, and other construction-related materials during a construction project. Any construction trailers are to be included in the construction staging area. In some cases, more than one staging area may be established on site.
    13. 13.  "County Urban Pocket Areas" refers to properties within unincorporated Multnomah County that are subject to the existing Intergovernmental Agreement to Transfer Land Use Planning Responsibilities Between the City of Portland and Multnomah County.
    14. 14.  "Diameter" refers to the cross-sectional size expressed in inches of a tree measured 4.5 feet above the ground. See Subsection 11.80.020 C., Measurements.
    15. 15.  "Days" means calendar days, unless specifically stated as working days. Working days include Monday through Friday, excluding holidays as identified in Human Resources Administrative Rule 6.02.
    16. 16.  “Development, Alteration” has the same meaning as in Title 33, Planning and Zoning.
    17. 17.  "Development Impact Area" is the area on a site affected by proposed site improvements, including buildings, structures, parking and loading areas, landscaping, and paved or graveled areas. The development impact area also refers to areas devoted to storage of materials, or construction activities such as grading, filling, trenching, or other excavation necessary to install utilities or access.
    18. 18.  "Development Permit" refers to permits issued by the City such as building permits, zoning permits, site development permits, public works permits and capital improvement projects.
    19. 19.  Development Types:
      1. a.  "Single Dwelling" refers to a house, attached house, or manufactured home with or without an accessory dwelling unit located on its own lot or parcel as those terms are defined in Title 33 Planning and Zoning
      2. b.  "One to Four Family Residential" refers to a house, attached house, accessory dwelling unit, duplex, attached duplex, triplex, fourplex, or manufactured home on one lot or parcel as those terms are defined in Title 33 Planning and Zoning.
      3. c.  "Multi-Dwelling Residential" refers to more than four dwelling units on a single lot or parcel, structures that contain five or more dwelling units that share common walls or floor/ceiling with one or more units, as well as Group Living, as defined in Title 33 Planning and Zoning.
      4. d.  "Commercial/Office/Retail/Mixed Use" means development that includes one or more of the following primary uses. The uses refer to the Use Categories in Title 33 Planning and Zoning: The uses are: Household Living, Commercial Parking, Quick Vehicle Servicing, Office, Retail Sales And Service, Self-Service Storage and Vehicle Repair.
      5. e.  "Industrial" means development that includes one or more of the following primary uses. The uses refer to the Use Categories in Title 33 Planning and Zoning. The uses are: Industrial Service, Manufacturing And Production, Warehouse And Freight Movement and Wholesale Sales.
      6. f.  "Institutional" means development that includes one or more of the following primary uses. The uses refer to the Use Categories in Title 33 Planning and Zoning. The uses are: Colleges, Community Service, Daycare, Medical Centers, Parks and Open Areas, Religious Institutions and Schools.
      7. g.  "Other" means development that includes one or more of the following primary uses referred to in Title 33 Planning and Zoning. The uses are: Commercial Outdoor Recreation, Major Event Entertainment and Basic Utilities.
    20. 20.  "Injury" means a wound inflicted upon a tree resulting from any activity, including trenching, excavating, altering the grade, smothering within the root protection zone of a tree, bruising, scarring, tearing or breaking of roots, bark, trunk, branches or foliage, herbicide or poisoning, or any other action leading to the death or permanent damage to tree health including the following:
      1. a.  "Disturbance" is the various activities from construction or development that may damage trees.
      2. b.  "Excessive Pruning" is removing in excess, one-fourth (25 percent) or greater, of the functioning leaf, stem or root area in a single growing season. Exceptions are when clearance from overhead utilities or public improvements is required or to abate a hazardous condition or other public nuisance. Excessive pruning does not include normal pruning that follows ANSI standards, see "Proper Arboricultural Practices," and "Pruning"
      3. c.  "Removal" is felling, cutting or removing any portion of the crown trunk, or root system of a tree, that results in the loss of physiological viability, or any procedure in which the natural result will lead to the death of the tree, including girdling, poisoning, topping or drowning the tree.
      4. d.  "Smothering" is the result of compaction or compression of the soil particles or texture that may result from the movement of heavy machinery and trucks, storage of construction materials, structures, paving, or any other means that creates an upper layer that is impermeable within the root protection zone.
      5. e.  "Topping" means the inappropriate pruning practice used to reduce tree height by cutting to a predetermined crown limit without regard to tree health or structural integrity. Topping does not include acceptable pruning practices as described in the American National Standards Institute (ANSI) "A‑300 Pruning Standards" and companion "Best Management Practices for Tree Pruning" published by the International Society of Arboriculture, such as crown reduction, utility pruning, or crown cleaning to remove a safety hazard, dead or diseased material. Topping is considered "removal".
    21. 21.  "Land Use Review" is a procedure for a specific use or development required under Title 33 Planning and Zoning.
    22. 22.  "Nuisance Plant List" is a list within the "Portland Plant List" that identifies nuisance trees and plants.
    23. 23.  "Overlay Zones and Plan Districts" refer to any of the following overlay zones or plan districts as shown on the Official Zoning Map, unless the specific regulation states otherwise:
      1. a.  Environmental Overlays shown on the Official Zoning Map with a "c" or "p".
      2. b.  Pleasant Valley Natural Resource Overlay, shown on the Official Zoning Map with a "v".
      3. c.  Willamette River Greenway Overlay Zones, as applied to the Natural "n", or Water Quality "q", overlays and only within or riverward of the greenway setback portion of the Recreational "r", General "g" and Industrial "i" overlays, as designated on the Official Zoning Map.
      4. d.  Scenic Resources Overlay, for trees located within scenic corridors, shown on the Official Zoning Map with an "s".
      5. e.  Aircraft Landing Zone, for trees located within the aircraft landing zone, shown on the Official Zoning Map with an “h”.
      6. f.  Johnson Creek Basin Plan District, only applied to the South subdistrict, to areas within the special flood hazard area, and to sites that abut the Springwater Corridor.
      7. g.  Rocky Butte Plan District.
      8. h.  South Auditorium Plan District.
    24. 24.  "Person" includes any individual, property owner, firm, association, corporation, agency, entity, or organization of any kind.
    25. 25.  "Proper Arboricultural Practices" refers to the methods employed during tree planting or cutting or removing any part of the branching structure of a plant in the crown, trunk or root areas in accordance the most recent edition of the American National Standards Institute (ANSI) "A-300 Standards" and published "Best Management Practices" of the International Society of Arboriculture.
    26. 26.  "Pruning" is the removal or reduction of parts of a tree that are not requisite to growth or production, are no longer visually pleasing, or are injurious to the health or development of the tree.
    27. 27.  "Public Agency" means any public agency or public utility as defined in ORS 757.005, or drainage district as defined in ORS 174.116.
    28. 28.  "Recognized Organization" is a neighborhood, community, business, or industrial association, or organization recognized or listed by the Office of Community & Civic Life. Recognized organization also includes the Office of Community & Civic Life LIFE district offices.
    29. 29.  "Responsible Engineer" for the Bureau of Transportation this shall be the City Engineer, for the Bureau of Environmental Services this shall be the Chief Engineer of the Bureau of Environmental Services, and for the Portland Water Bureau this shall be the Chief Engineer of the Portland Water Bureau. Each Responsible Engineer may delegate their authority and duties to another employee in the same bureau. The duties are as prescribed in Section 11.10.010.
    30. 30.  "Responsible Party" is a person in control of property in fee ownership or tenancy where a tree is located or property adjacent to a Street Tree. The responsible party may include the owner or owners, lessees, tenants, occupants or other persons in charge. In cases of violations, the responsible party may also include the person, partnership, or corporation who violated the provisions of this Title.
    31. 31.  "Site" has the same meaning as in Title 33 Planning and Zoning.
    32. 32.  "Street" has the same meaning in Section 9-101 of the City Charter.
    33. 33.  "Treatment" is the application of therapeutic remedies or corrections to site conditions when injury to trees has occurred to improve the chances of long term viability. Generally these measures should occur only under the direction of an arborist. Treatment measures include compensatory or corrective pruning, fertilization, inoculation, soil fracturing, grade restoration and supplemental irrigation.
    34. 34.  "Tree Area" is the amount of area on a development site that is used to calculate the required number of trees to be planted to meet tree density standards.
    35. 35.  "Tree Plan" is a site plan showing trees to be preserved and protected, planted, or removed. Specific requirements for Tree Plans are in Chapter 11.50.
    36. 36.  Tree Related Terms:
      1. a.  "City Tree" is a tree within City limits that is on property owned or managed by the City. A tree that straddles a property line between private property and City-owned or -managed property is a Private Tree, shared by the City and adjacent property owner. A tree on a property line between City-owned or managed property and the street is a Street Tree.
      2. b.  "Dangerous Tree" is one where the condition of the tree presents a foreseeable danger of inflicting damage that cannot be alleviated by treatment, pruning, or by making practicable site condition modifications. A tree may be dangerous because it is likely to injure people or damage vehicles, structures, or development, such as sidewalks or utilities.
      3. c.  "Dead Tree" is a tree that is dead or has been damaged beyond repair or where not enough live tissue, green leaves, limbs, or branches exist to sustain life as determined by an arborist.
      4. d.  "Dying Tree" is a tree in an advanced state of decline because it is diseased, infested by insects or rotting and cannot be saved by reasonable treatment or pruning, or must be removed to prevent spread of the infestation or disease to other trees or is imminently likely to become a danger or die.
      5. e.  "Heritage Tree" is a tree designated as a Historic Landmark Tree, a Historic Tree, or a Heritage Tree.
      6. f.  "Native Tree" is a tree listed on the "Portland Plant List" as native to the Willamette Valley.
      7. g.  "Non-Native Non-Nuisance Species Tree" is a tree that is not identified on the Portland Plant List as a native species or a nuisance species tree.
      8. h.  "Nuisance Species Tree" is a tree of a species listed on the "Nuisance Plant List".
      9. i.  "Protected Tree" is a tree that shall be retained and protected because of a condition of approval on a land use review, a tree plan, or because it is a Heritage Tree.
      10. j.  "Private Tree" is a tree on property that is not owned or managed by the City. A tree that straddles a property line between private property and City-owned or –managed property is a Private Tree, shared by the City and adjacent property owner. A tree that straddles a private property line and the street is a Street Tree.
      11. k.  "Street Tree" means any tree growing in or upon any city managed street. In some cases, property lines lie several feet behind the sidewalk or edge of road pavement. Where a street is not fully improved with curbs or sidewalks but is paved, a tree may be considered a Street Tree if it is located within 15 feet of the edge of pavement, unless a survey by a licensed surveyor or property boundaries can clearly establish otherwise. For completely unimproved streets, the actual property line will be used to demarcate between Private Trees and Street Trees. A tree that straddles a private property line and the street is a Street Tree.
      12. l.  "Tree" means a perennial, woody stemmed plant that typically supports a distinct crown of foliage and typically reaches a mature height of at least 16 feet and excludes plants listed as shrubs or herbaceous plants in the Tree and Landscaping Manual published by the Bureau of Development Services or the Portland Plant List.
      13. m.  "Tree Grove" is a group of six or more native trees at least 12 inches in diameter, or Oregon white oak trees or Pacific madrone trees that are at least 6 inches in diameter and that form a generally continuous canopy, or are spaced as appropriate for that species or species assemblage. Groves are generally non-linear. Other trees and understory vegetation located within the grove are considered part of the grove and are counted as part of the canopy area. A tree grove may be identified by a qualified professional, such as an arborist or environmental scientist, based on the types, configuration, or functions of a grouping of trees. Functions include structural support and wind protection for the trees within the grove, microclimate and shade, and habitat such as nesting, foraging, and cover for birds and other wildlife.
    37. 37.  "Utility" is a public utility, business, or organization that supplies energy, gas, heat, steam, water, communications, or other services through or associated with telephone lines, cable service and other telecommunications, sewage disposal and treatment, and other operations for public service. It does not include transportation service, railroad operations, or service otherwise licensed under City Code
    38. 38.  "Watershed" means one of the areas as shown in Figure 80-1 and further defined by the Bureau of Environmental Services. For the purposes of establishing planting within a specific watershed as part of this Title, watersheds end at the City limits and the following also apply:
      1. a.  Columbia Slough – sites on Hayden Island are included in this watershed
      2. b.  Willamette River – sites in Northwest Portland that are west of the Willamette River watershed are included in this watershed
      3. c.  Fanno Creek/Tryon Creek – these two watersheds are managed as a single watershed unit
      4. d.  Johnson Creek – all sites within the Johnson Creek watershed
      5. Figure 80-1 Watershed Boundaries

  3. ​​​C.  Measurements. For the purposes of establishing distances and other types of required measurements, the following methods are applied.

    1. 1.  Root Protection Zone (Prescriptive Path). To determine the required root protection zone, measure the size of the tree to be protected. For each diameter inch of the tree, measure one foot away from the tree to establish the radius of the circle surrounding the tree. Each 1 inch diameter of tree requires 1 foot radius for the root protection zone. See Figure 80-2.
    2. Figure 80-2 Root Protection Zone

      2.  Tree Location. A tree’s location for purposes of establishing the applicable requirements of this Title is determined by the trunk at the point where it meets the ground. Surface roots extending from the trunk are not used to determine the tree’s location.

    3. 3.  Measuring Tree Size

      1. a.  New trees. New trees are measured in caliper inches, which is the diameter of the trunk 6 inches above the soil or root ball for bare root trees. For coniferous trees, tree height is used. See Figure 80-3.

      2. Figure 80-3 Measuring Tree Size for New Trees

        b.  Existing trees.

        1. (1)  Existing trees are generally measured in terms of diameter inches at a height of 4-1/2 feet above the ground. See Figure 80-4. The diameter may be determined by measuring the circumference of the tree trunk and dividing by 3.14.

        2.  Figure 80-4 Measuring Tree Size for Existing Trees

        3. (2)  When the trunk is at an angle or is on a slope, the trunk is measured at right angles to the trunk 4.5 feet along the center of the trunk axis, so the height is the average of the shortest and the longest sides of the trunk; see Figure 80-5.
        4. Figure 80-5 Measuring Existing Trees with an Angle or on Slopes

        5. (3)  When the trunk branches or splits less than 4.5 feet from the ground, measure the smallest circumference below the lowest branch. See Figure 80-6.
        6. Figure 80-6 Measuring Split Trunk Tree

        7. (4)  For multi-stemmed trees, the size is determined by measuring all the trunks, and then adding the total diameter of the largest trunk to one-half the diameter of each additional trunk (see Figure 80-7). A multi-stemmed tree has trunks that are connected above the ground and does not include individual trees growing close together or from a common root stock that do not have trunks connected above the ground.
        8. Figure 80-7 Measuring Multi-stemmed Trees