1. Purpose. The purpose of this subdivision is to encourage tree preservation by reasonably limiting the removal of trees during construction, site work, and land development activities, as well as to mitigate for the loss of trees due to these activities while maintaining the rights of existing homeowners to use their private property.
2. Findings. The city of Minnetonka finds that trees and woodlands are an integral part of the city's identity. As such, the city finds that standards governing the preservation, protection, and planting of tree resources are necessary to:
a) Maintain and enhance, as much as practical, the diversity and extent of the city’s trees and woodlands while balancing community responsibilities with private property rights.
b) Maintain buffers between similar land uses and maintain and establish buffers between conflicting land uses;
c) Promote climate resilience;
d) Improve air quality and reduce noise pollution;
e) Enhance energy conservation through natural insulation and shading;
f) Reduce the urban heat island effect;
g) Reduce soil erosion, sedimentation, and stormwater runoff;
h) Preserve habitat for wildlife, including pollinating insects;
i) Extend the life of roadways;
j) Increase and maintain property values; and
k) Promote the positive impacts of trees on society, such as lowering stress, reducing noise, and calming traffic.
3. Applicability. The provisions of this subdivision apply whenever construction, site work, development, or redevelopment activities occur on a property.
4. Authority. Consistent with the purpose of this subdivision, and in order to enforce its provisions, the city may:
a) Identify, require, and enforce a tree preservation plan as described in subdivision 6 below;
b) Specify trees or groups of trees for preservation;
c) Establish grading limits;
d) Require the clustering of buildings or the relocation of roads, drives, buildings, utilities, or storm water facilities when relocation would preserve protected trees;
e) Specify time periods in which tree cutting, pruning, or injury may not occur in order to prevent the spread of disease;
r) Require conservation easements or other legal means to ensure that woodland preservation areas or groups of high priority trees or significant trees are not intentionally destroyed after the development has been approved; and
g) Grant variances from the provisions of this section 314.01, subject to the limitations and procedures outlined in City Code 300.07;
5. Definitions. For the purpose of this ordinance, the terms below have the meaning given to them:
a) "Basic Tree Removal Area" - consists of the following:
1) within the areas improved for reasonably-sized driveways, parking areas, and structures without frost footings and within ten feet around those improvements;
2) within the footprints of, and 20 feet around, buildings with frost footings;
3) within the footprints of, and 10 feet around, structures with post footings such as decks or porches, if the structure is located at or outside of the area allowed by paragraph (a)(2) of this subdivision 5; and
4) in areas where trees are being removed for ecological restoration in accordance with a city-approved restoration plan.
b) "Canopy" - the uppermost layer of a forest formed by tree crowns.
c) “Construction” - the activity of building a new principal or accessory structure or adding on to an existing principal or accessory structure.
d) "Critical root zone" - the minimum area around a tree that must remain undisturbed. The critical root radius is calculated by measuring the tree's diameter at standard height. For each inch of tree diameter, 1.5 feet of root zone radius must be protected. For example, if a tree's dsh is 10 inches, then its critical root zone radius is 15 feet (10 x 1.5 = 15).
e) "Diameter at standard height (dsh)" - the diameter of a tree measured at 4.5 feet above the base of the tree. Multi-stem trees are considered one individual tree, and each stem must be measured 4.5 feet above the base of the stem and added together to determine the diameter of the multi-stem tree.
f) “Redevelopment” - removal and reconstruction of more than 50% of the square footage of a principal structure in any zoning district or a more-than-50% increase in the square footage of structure or structures on a site.
g) “Removal/Removed” - the physical removal of a tree or: (1) girdling; (2) injury to 30 percent or more of the trunk circumference; (3) pruning of 30% or more of the crown; (4) trimming an oak between April 1st and July 15th; or (5) compacting, cutting, filling, or paving 30 percent of the critical root zone for all tree species.
h) "Sapling" - a tree generally one to three years old.
i) “Site work” - work on a property or properties that involves filling, excavating, or moving earth by any means, mechanized or otherwise, requiring a grading permit. Site work does not include the planting of trees or other vegetation.
j) "Tree, high priority" - a tree that is not in a woodland preservation area but is still important to the site and the neighborhood character, that is structurally sound and healthy, and that meets at least one of the following standards as outlined below. The city forester prioritizes native and culturally significant trees species above non-native native trees.
The city will maintain, and periodically update, a list of prioritized and acceptable tree species. This list may be used to guide both tree removals and mitigation.
1) a deciduous tree that is at least 10 inches dsh.
2) a coniferous tree that is at least 15 feet in height that is not in a group as described below; or
3) a tree that is in a group of three or more deciduous trees that are at least eight inches dsh or coniferous trees that are at least 15 feet in height, that provide a buffer or screening along an adjacent public street, and that is within 50 feet of an arterial road and 35 feet of a minor collector, local, or private street and a trail. This distance will be measured from the edge of the pavement or curb of the road, street, or trail.
k) "Tree, protected" - a tree that is in a woodland preservation area, or is a high priority tree, or significant tree.
l) "Tree, significant" - a tree that is structurally sound and healthy and that is either a deciduous tree at least four inches dsh or a coniferous tree at least 10 feet in height.
m) "Understory" - The trees, shrubs, and herbaceous plants that grow in the shade of the forest canopy, including trees that could potentially grow to reach the canopy.
n) "Woodland preservation area" - a remnant woodland ecosystem that is at least two acres in size regardless of property boundaries, is generally mapped in the city's Minnesota Land Cover Classification System, and although it may be degraded, it generally meets the criteria for one of the following types of ecosystems as reasonably determined by the city:
1) "floodplain forest" - an area populated by deciduous tree species tolerant of seasonal flooding and deposition of silty or sandy soils. The canopy cover is extremely variable, and mature trees are typically greater than 70 feet tall. The dominant tree species in the canopy are silver maple and eastern cottonwood. In floodplain areas with severe flooding, the understory will be sparsely vegetated. Trees in the understory include saplings from the canopy species, green ash, black willow, slippery elm, American elm, boxelder, and hackberry;
2) "lowland hardwood forest" - an area with a flat terrain populated by deciduous tree species tolerant of periodic soil saturation from seasonally high water tables. The soils are moderately well to poorly drained. The dominant tree species in the canopy are American elm, black ash, basswood, bur oak, red oak, white oak, quaking aspen, paper birch, and red maple. Trees in the understory include saplings from the canopy species, slippery elm, green ash, butternut, sugar maple, quaking aspen, balsam poplar, and American hornbeam. The large shrub or small tree layer of the understory is typically dense and can include ironwood, pagoda dogwood, prickly ash, American hazelnut, gray dogwood, and speckled alder;
3) "maple basswood forest" - an area with well-drained soils and populated by a variety of shade-tolerant, fire-sensitive, deciduous tree species. The mature trees are straight with narrow crowns greater than 60 feet tall. The dominant tree species in the canopy are basswood and sugar maple, but mesic species such as slippery elm, red oak, bur oak, green ash, white ash, and black ash may be found as well. Trees in the understory include saplings from the canopy species, bitternut, black cherry, and ironwood. The large shrub or small tree layer of the understory is composed of primarily tree seedlings and herbaceous plants;
4) "mesic oak forest" - an area populated by tall, single-stemmed deciduous trees greater than 60 feet tall that lack spreading lower branches. Mesic oak forests may have a moderately moist habitat but can be dry depending on the slope and aspect of the forest. The dominant tree species in the canopy include red oak, white oak, and bur oak. Trees in the understory include saplings from the canopy and fire-sensitive species such as basswood, green ash, bitternut hickory, big-toothed aspen, butternut, northern pin oak, black cherry, paper birch, American elm, boxelder, and red maple. The large shrub or small tree layer in the understory tends to be sparse with greater herbaceous plant diversity but can include ironwood, chokecherry, prickly ash, American hazelnut, prickly gooseberry, red-berried elder, nannyberry, juneberry/serviceberry, and pagoda dogwood;
5) "oak woodland brushland" - an area with a canopy more open than a forest but less open than a savanna. It is characterized by open-grown trees and a distinct shrub layer in well-drained sandy, gravelly soils. The dominant tree species include red oak, northern pin oak, white oak, bur oak, and aspen. When it exists, the trees in the understory include saplings from the canopy, black cherry, and red cedar. The large shrub or small tree layer can include American hazelnut, ironwood, juneberry, and chokecherry;
6) "tamarack swamp" - an area that is a forested wetland community dominated by patches of tamarack, a deciduous coniferous tree. The dominant tree species in the canopy include tamarack, black spruce, paper birch, and red maple. The trees in the understory include saplings from the canopy, and the large shrub or small tree layer can include speckled alder and red osier dogwood; or
7) "willow swamp" - an area that is a forested wetland community or an area with seasonally flooded soils and scattered-to-dense shrub cover. The dominant tree species in the canopy include black willow and speckled alder. The trees in the understory include saplings from the canopy, and the large shrub or small tree layer can include several species of willow and dogwood.
6. Tree Preservation Plan. A tree preservation plan is required as part of any application that involves construction, site work, or redevelopment activities. A tree preservation plan must include:
a) A tree inventory, in spreadsheet format, that includes the following:
1) The species, sizes, and locations of high priority trees, significant trees, and trees in woodland preservation areas, regardless of health. Dead, diseased or structurally unsound trees, and trees infested with a disease or insect, should be noted as such in the inventory.
2) An inventory of all canopy species that exist in woodland preservation areas, including those that are in the understory, if they are four inches dsh or larger. Understory trees, excluding canopy species, and large shrubs that exist in woodland preservation areas must be inventoried if they are two inches dsh or larger.
3) The size of high priority trees and significant trees, regardless of location.
4) The size of coniferous trees recorded in dsh and approximate height, regardless of location.
Note: Invasive plants such as buckthorn and honeysuckle should not be inventoried.
b) A site plan that illustrates the dsh, location and critical root zone for each protected tree – including the trees to be removed and the trees to be preserved, the proposed construction limits, and the proposed tree protection methods in addition to construction limit fencing. If grading or construction limits are outside of a woodland preservation area, the trees in that woodland preservation area may be grouped together.
7. Tree Removal.
a) General Standards. The removal of protected trees during construction, site work, development, or redevelopment activities must comply with the following:
1) Principal structures and associated facilities must be located to maximize tree preservation. The city may specify the location of the principal structures and associated facilities in order to ensure a reasonable tree preservation.
2) In no case may trees be removed from a conservation easement without the approval of city staff.
3) Trees required to be saved as part of a subdivision approval must remain on a lot for two years after the final building permit inspection or certificate of occupancy is issued for the principal structure, whichever is later. Any tree that dies solely of natural causes such as disease or wind is exempt from this section.
4) An applicant and property owner must comply with any approved tree preservation or landscape plan. In the event that a tree preservation or landscape plan is not on file with the city, any tree removed without authorization from the city will be considered part of the approved tree preservation or landscape plan.
5) A healthy protected tree that did not pose a significant or severe risk to personal safety or property damage and that was removed or otherwise destroyed by unnatural causes within three years before a redevelopment or subdivision application will be regarded as if it were present at the time of construction or a development application. In no case may healthy protected trees be removed from properties required to have a tree preservation or landscape plan unless first approved by the city.
b) Specific Standards. Protected trees may be removed as follows:
Woodland Preservation Area (WPA) | High-Priority Trees* | Significant Trees* | ||
Single-Family Property | No construction or site work | Removal is not restricted, except as outlined in subd. 7(a) above | ||
Construction on a vacant lot | In conformance with subdivision approvals | |||
Construction or site work, two years after initial house construction | Removal is not restricted, except as outlined in subd. 7(a) above | |||
Redevelopment | 25% of WPA on the lot | 35% of trees on the lot | 50% of trees on the lot | |
Non-Single-Family Property | No construction or site work | In conformance with approved landscape or tree preservation plan | ||
Construction or site work on a vacant lot | In conformance with subdivision or site plan approval | |||
Construction or site work on a developed lot | 25% of WPA on site | 35% of trees on site | 50% of trees on site | |
Redevelopment | 25% of WPA on site | 35% of trees on site | 50% of trees on site | |
Subdivision | 25% of area on site | 35% of trees on the site | 50% of trees on the site | |
If a subdivision proposal includes removal of trees above the thresholds listed above, the subdivision must occur at a density of no more than 1 unit/acre | ||||
* located outside of a WPA
c) In addition to the on-site woodland preservation area removal thresholds outlined in the chart above, the city may consider a proposal’s impact on the cumulative removal within the larger woodland preservation area.
d) Exceptions. The city council may allow removal of protected trees over the percentages listed in the chart above if:
1) The removal would promote a greater public good, such as:
* providing reasonable use or access to the property;
* providing affordable housing;
* allowing for the creation or rehabilitation of a public road or trail;
* providing for a public utility service, such as a transmission line, stormwater pond, or a water tower;
* allowing for the creation or rehabilitation of a public park;
* enabling redevelopment in a designated redevelopment area;
* or other public good recognized by the city.
2) The removal of some trees would promote the preservation of important or unique natural features of trees on the property or site.
3) The removal of some trees would promote the planting or growth of more climate-resilient trees or vegetation on the property or site.
4) A variance is granted under Section 300.07 of the zoning ordinance.
8. Tree Mitigation.
a) Mitigation Required. Mitigation is required for trees removed, as follows.
Mitigation is Required For: | ||
Single-Family Property | No construction or site work | N/A. Removal not restricted, except as outlined in subd. 7 above. |
Construction on a vacant lot | * High priority trees, significant trees, and trees within woodland preservation removed outside of: (1) the basic tree removal area; and (2) the width of required easements for public and private streets and utilities. | |
Construction or site work, two years after initial house construction | ||
Redevelopment | * High priority and significant trees removed for surface stormwater practices.
| |
Non-Single- Family Property | No construction or site work | * Trees part of an approved tree preservation or landscape plan. |
Construction or site work on a vacant lot | * High priority trees, significant trees, and trees within woodland preservation removed outside of: (1) the basic tree removal area; and (2) the width of required easements for public and private streets and utilities. | |
Construction or site work on a developed lot | ||
Redevelopment |
* High priority and significant trees removed for surface stormwater practices. | |
Subdivision | * High priority trees, significant trees, and trees within woodland preservation removed outside of: (1) the basic tree removal area; and (2) the width of required easements for public and private streets and utilities. * High priority and significant trees removed for surface stormwater practices. | |
b) Mitigation Plan. When tree mitigation is required, the applicant must submit a tree mitigation plan for staff review and approval. The plan must indicate the number of inches or feet of mitigation trees, the species and quantity of each species, and the caliper size or feet and location for each replacement tree. The plan may not be comprised of more than 10 percent of the same species or size unless approved by the city. The plan must comply with the mitigation standards required below. The applicant must implement the tree mitigation plan approved by city staff.
c) Mitigation Standards. Mitigation for removal of trees or large shrubs in woodland preservation areas, high priority trees, and significant trees must meet the following standards:
Woodland Preservation Area | High-Priority Tree | Significant Tree | |
Rate | One inch for each inch in diameter of a deciduous tree removed and one foot for each foot in height of a coniferous tree removed | Two inches dsh replanted per tree removed | |
Species | Species found in that eco- type, as specified on the list of acceptable replacement species on file with the city | Species of a similar type that are normally found growing in similar conditions and that are included on the list of acceptable replacement species on file with the city; | Any tree species, as approved by city staff |
Size | * Deciduous balled and burlapped trees: at least 1.25 inches, but not more than 3 inches dsh * Deciduous spade moved trees: at least 3 inches, but not more than 6 inches * Understory or small trees: at least #7 container stock * Shrubbery: at least #3 container stock * Coniferous balled and burlapped trees: at least 6 feet, but not more than 8 feet in height * Coniferous spade moved: at least 8 feet, but not more than 14 feet. | Deciduous: no less than two inches dsh replanted per tree removed Conifer: no less than six feet in height replanted per tree removed | |
In addition,
1) Mitigation trees must be planted on the same property or development area from which the trees were removed. The city recognizes that, in some unique situations, site conditions may not allow a property owner or applicant to achieve the required on-site mitigation. In such cases, and at the sole discretion of city staff, a property owner or applicant may be required to provide cash in lieu of the required mitigation that cannot be planted on site. Such funds would be deposited into the city’s natural resources fund.
2) If larger trees are allowed, a three-year financial guarantee may be required.
3) The required mitigation trees must be replaced by the current property owner if the trees have died, have severely decline, or have been damaged after the end of the second full growing season following installation. A tree will be considered to be severely declined if more than 25 percent of the crown has died.
4) Development that is subject to landscape requirements in sections 300.27 and 300.31 must meet the minimum landscape requirements of the applicable section. Trees planted as part of a required landscaping plan may be counted as mitigation trees under this section, at the city's discretion.
5) All mitigation trees and shrubs must meet the American National Standards Institute (ANSI A300 and as amended) relating to planting guidelines, quality of stock, and appropriate sizing of the root ball for balled and burlapped, containerized, and spade- moved trees.
6) The city may require an escrow deposit to ensure the required planting and continued existence of the mitigation trees. The city will release the escrow deposit after the end of the second full growing season following installation of the mitigation trees and any replacement trees.
9. Construction.
a) Before construction or site work – including any tree removal – tree protection fencing or other approved protection measures must be installed for city staff inspection. The location of the fencing/protection measures must be in conformance with the approved tree preservation plan and must be maintained throughout the course of construction or site work.
b) No construction, compaction, construction access, stockpiling of earth, storage of equipment or building materials, or grading of any kind may occur within the critical root zone areas of trees to be protected.
c) An area of new or compensatory water storage may not be located where there are woodland preservation areas, high priority trees, or significant trees unless approved by the city. Mitigation will be required for the loss of woodland preservation areas and high- priority trees due to ponding. The compensatory storage area must be created in a manner that prevents erosion into any nearby water resource.
10. Violations
a) Each protected tree that is removed in violation of ordinance requirements is a separate violation of the city code.
b) A tree or shrub that was required by the city to be saved but was removed must be replaced at a rate of 2:1 based on dsh for deciduous species and height for conifers. The city may also impose a financial penalty equal to $500 for each inch of dsh or foot of height removed, not to exceed $2,000 for each tree or shrub. This provision also applies to a conservation easement area that is disturbed during or after development.
11. Exemptions. Linear projects, utility maintenance projects, and associated activities undertaken by a government unit are exempt from the provisions of this ordinance. Plans must be designed to protect as many trees as practicable and must be provided to natural resources staff for review and comment.
(Added by Ord. No. 2021-24, effective October 10, 2021)