Division II. Critical Areas

Chapter 16.20


16.20.010    Finding.

16.20.020    Purpose.

16.20.030    Definitions.

16.20.040    Critical areas code.

16.20.045    Best available science.

16.20.050    Fees.

16.20.060    Applicability.

16.20.065    Mitigation sequencing.

16.20.070    Exemptions.

16.20.080    Review process.

16.20.090    Critical area reports.

16.20.100    Previous studies.

16.20.110    Mitigation plan requirements.

16.20.115    Financial guarantee.

16.20.120    Independent review of critical area report.

16.20.130    Substantive requirements.

16.20.140    Restoration work.

16.20.145    Reasonable use exception.

16.20.150    Enforcement and inspections.

16.20.160    Limited density transfer.

16.20.170    Preexisting developments and uses.

16.20.010 Finding.

The city finds that:

A. Critical areas’ biological and physical functions benefit the city by protecting water quality, providing fish and wildlife habitat, supporting the food chain, storing and conveying floodwaters, recharging groundwater, controlling erosion, and providing aesthetic values and recreation;

B. Development within critical areas may also pose a threat to human safety or to public and private property;

C. Healthy and well-functioning ecosystems are more likely to withstand natural disasters; and

D. Access to natural ecosystems has been proven to improve the mental and physical health of individuals. (Ord. 1615 § 2, 2019; Ord. 1070 § 2, 2004).

16.20.020 Purpose.

The purpose of this critical areas code is to:

A. Protect the functions and values of ecologically sensitive areas while allowing for economically reasonable use of private property, through the application of the best available science;

B. Implement the Growth Management Act, Puget Sound Action Agenda, Watershed Protect Plan, and the goals and policies of the Environmental Stewardship Element of the comprehensive plan;

C. Protect members of the public and public resources and facilities from injury and loss due to slope failures, erosion, seismic events, volcanic eruptions, or flooding;

D. Meet the requirements of the National Flood Insurance Program, maintaining the city of Bonney Lake as an eligible community for federal flood insurance benefits;

E. Alert members of the public including, but not limited to, appraisers, owners, potential buyers or lessees to the development limitations of critical areas;

F. Provide decision makers with sufficient information to protect critical areas; and

G. Conserve the biodiversity of plant and animal species, protect, maintain, and restore healthy, functioning ecosystems through the protection of unique, fragile, and valuable elements of the environment, including, but not limited to, ground and surface waters, wetlands and lakes, fish and wildlife and their habitats. (Ord. 1615 § 2, 2019; Ord. 1070 § 2, 2004).

16.20.030 Definitions.

100-Year Flood. See “Base flood.”

“Anadromous” refers to fish that spawn and rear in freshwater and mature in saltwater.

“Applicant” means a person who applies for a permit, reasonable use exception, written exemption, and/or approval of a critical areas report from the city.

“Aquifer” means a geological formation capable of yielding water to a well or spring.

“Area of shallow flooding” means a designated Zone AO, AH, AR/AO or AR/AH (or VO) on a community’s Flood Insurance Rate Map (FIRM) with a one percent or greater annual chance of flooding to an average depth of one to three feet where a clearly defined channel does not exist, where the path of flooding is unpredictable, and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow. Also referred to as the sheet flow area.

“Area of special flood hazard” means land in the floodplain within the city subject to a one percent or greater chance of flooding in any given year. It is shown on the Flood Insurance Rate Map (FIRM) as Zone A, AO, AH, A1-30, AE, A99 or AR (V, VO, V1-30, VE). “Special flood hazard area” is synonymous in meaning with the phrase “area of special flood hazard.”

“ASCE 24” means the most recently published version of ASCE 24, Flood Resistant Design and Construction, published by the American Society of Civil Engineers.

“Base flood” means the flood having a one percent chance of being equaled or exceeded in any given year.

“Base flood elevation” or “BFE” means the elevation to which floodwater is anticipated to rise during the base flood.

“Basement” means any area of the building having its floor subgrade, or below ground level, on all sides.

“Best management practices” means those practices which provide the best available and reasonable physical, structural, managerial, or behavioral activity to reduce or eliminate pollutant loads and/or concentrations leaving the site.

“Breakaway wall” means a wall that is not part of the structural support of the building and is intended through its design and construction to collapse under specific lateral loading forces without causing damage to the elevated portion of the building or supporting foundation system.

“Buffer” means an area contiguous to and required for protection of a critical area measured outward in each direction, on the horizontal plane from the delineated edge of the critical area.

“Conservation easement” means a legal agreement that the property owner enters into to restrict uses of the land in a manner that conserves natural functions.

“Critical aquifer recharge area” means an area with a critical recharging effect on aquifers used for potable water, as discussed in WAC 365-190-080(2).

“Critical area” means those areas listed in BLMC 16.20.060.

“Critical areas code” means Division II of this title entitled Critical Areas, consisting of Chapters 16.20 through 16.30 BLMC.

“Critical facility” means a facility for which even a slight chance of flooding might be too great. Critical facilities include, but are not limited to, schools, nursing homes, hospitals, police, fire and emergency response installations, and installations that produce, use, or store hazardous materials or hazardous waste.

“Development” means any manmade change to improved or unimproved real estate, including but not limited to buildings or other structures, land disturbing activity, paving, or storage of equipment or materials within critical areas or associated buffers, including city approvals that establish patterns of use such as subdivisions, short subdivisions, rezones, and conditional use permits.

“Development factor” means the number used in a limited density transfer to calculate modified net acres for calculating the number of housing units that may be built on a parcel or parcels partially encumbered by a critical area.

“Ecosystem” means a spatially explicit unit of the Earth that includes all of the organisms, along with all components of the abiotic environment. Ecosystems have composition, structure, and functions.

“Ecosystem function” means (1) the process or the cause-effect relationship underlying two or more interacting components, e.g., terrestrial plant material as food/substrate for aquatic invertebrates; (2) the sum of processes that sustain the system; and (3) the capacity of natural processes and components to provide goods and services that satisfy human needs, either directly or indirectly. Ecosystem functions can be conceived as a subset of ecological processes and ecosystem components and structure.

“Ecosystem process (or ecological process)” means the complex interactions between biotic (living organisms) and abiotic (chemical and physical) components of ecosystems through the universal driving forces of matter and energy.

“Ecosystem structure” means the arrangement of and relations among the parts or elements (components) of an ecosystem.

“Elevated building,” for insurance purposes, means a nonbasement building that has its lowest elevated floor raised above ground level by foundation walls, shear walls, post, piers, pilings, or columns.

“Elevation certificate” means an administrative tool of the National Flood Insurance Program (NFIP) that can be used to provide elevation information, to determine the proper insurance premium rate, and to support a request for a Letter of Map Amendment (LOMA) or Letter of Map Revision based on fill (LOMR-F).

“Environmental impact remediation” means the reduction of a pollutant in contaminated soil, groundwater, or surface water, the purpose of which is both to reduce the level of the pollutant and to protect people and the environment against its potentially harmful effects.

“Essential facility” has the same meaning as “essential facility” defined in ASCE 24. Table 1-1 in ASCE 24-14 further identifies building occupancies that are essential facilities.

“Existing manufactured home park or subdivision” means a manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed is completed before the effective date of the adopted floodplain management regulations, including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads.

“Expansion to an existing manufactured home park or subdivision” means the preparation of additional sites by the construction of facilities for servicing the lots on which the manufactured homes are to be affixed, including the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads.

“Farmhouse” means a single-family dwelling located on a farm site where resulting agricultural products are not produced for the primary consumption or use by the occupants and the farm owner.

“Fish and wildlife habitat conservation areas” are areas that serve a critical role in sustaining needed habitats and species for the functional integrity of the ecosystem, and which, if altered, may reduce the likelihood that the species will persist over the long term. These areas may include, but are not limited to, rare or vulnerable ecological systems, communities, and habitat or habitat elements including seasonal ranges, breeding habitat, winter range, and movement corridors, and areas with high relative population density or species richness. Fish and wildlife habitat conservation areas do not include such artificial features or constructs as irrigation delivery systems, irrigation infrastructure, irrigation canals, or drainage ditches that lie within the boundaries of, and are maintained by, a port district or an irrigation district or company.

“Flood” or “flooding” means:

1. A general and temporary condition of partial or complete inundation of normally dry land areas from:

a. The overflow of inland waters.

b. The unusual and rapid accumulation of runoff of surface waters from any source.

c. Mudslides (i.e., mudflows) which are proximately caused by flooding as defined in subsection (1)(b) of this definition and are akin to a river of liquid and flowing mud on the surfaces of normally dry land areas, as when earth is carried by a current of water and deposited along the path of the current.

2. The collapse or subsidence of land along the shore of a lake or other body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels or suddenly caused by an unusually high water level in a natural body of water, accompanied by a severe storm, or by an unanticipated force of nature, such as flash flood or an abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in flooding as defined in subsection (1)(a) of this definition.

“Flood elevation study” means an examination, evaluation and determination of flood hazards and, if appropriate, corresponding water surface elevations, or an examination, evaluation and determination of mudslide (i.e., mudflow) and/or flood-related erosion hazards.

“Flood Insurance Rate Map (FIRM)” means the official map on which the Federal Insurance Administration has delineated both the special hazard areas and the risk premium zones applicable to the city of Bonney Lake.

Flood Insurance Study (FIS). See “Flood elevation study.”

“Floodplain” or “floodprone area” means any land area susceptible to being inundated by flooding.

“Floodplain administrator” means the planning and building supervisor who has been designated to administer and enforce the floodplain management regulations.

“Floodplain management” means the operation of an overall program of corrective and preventive measures for reducing flood damage, including but not limited to emergency preparedness plans, flood control works, and floodplain management regulations.

“Floodplain management regulations” mean the zoning ordinances, subdivision regulations, building codes, health regulations, special purpose ordinances (such as floodplain ordinance, grading ordinance and erosion control ordinance) and other applications of police power. The term describes such state or local regulations, in any combination thereof, which provide standards for the purpose of flood damage prevention and reduction.

“Floodproofing” means any combination of structural and nonstructural additions, changes, or adjustments to structures which reduce or eliminate risk of flood damage to real estate or improved real property, water and sanitary facilities, structures, and associated contents. Floodproofed structures are those that have the structural integrity and design to be impervious to floodwater below the base flood elevation.

“Floodway” means the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than one foot. Also referred to as the “regulatory floodway.”

“Functional arrays” means forage, floodwater restraint, hiding habitat, or other physical or biologic roles in the ecosystem, that singly or in combination correspond to those of the native species.

“Functionally dependent use” means a use which cannot perform its intended purpose unless it is located or carried out in close proximity to water. The term includes only docking facilities, port facilities that are necessary for the loading and unloading of cargo or passengers, and ship building and ship repair facilities, and does not include long-term storage or related manufacturing facilities.

“Functions and values” means the benefits conferred by critical areas, including, but not limited to, water quality protection, fish and wildlife habitat, flood storage and conveyance, groundwater recharge, erosion control, and protection from hazards.

“Geologically hazardous areas” means areas that, because of their susceptibility to erosion, landslide, seismic events, or volcanic hazards, require a heightened level of review for public health or safety reasons.

“Hazard tree” means a tree that has significant structural defects that are likely to lead to failure and possibly cause injury or damage as identified in a report from an International Society of Arboriculture (ISA) tree risk assessment qualified (TRAQ) arborist. In the case of steep slopes, a hazard tree can also be a tree that is a hazard to stability of the slope, as determined by a geotechnical engineer.

“Hazardous substance” means a liquid, solid, or gas that exhibits any of the properties described in WAC 173-303-090 or 173-303-100.

“Highest adjacent grade” mean the highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure.

“Historic” means existing before the area was altered by human activity.

“Historic structure” means any structure that is:

1. Listed individually in the National Register of Historic Places (a listing maintained by the Department of the Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;

2. Certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district;

3. Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary of the Interior; or

4. Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either:

a. By an approved state program as determined by the Secretary of the Interior; or

b. Directly by the Secretary of the Interior in states without approved programs.

“Hyporheic zone” means the area beneath and alongside a stream channel where surface water infiltrates and exchanges with subsurface flow.

“Impact” means to adversely affect a natural system or increase the hazard which a natural system poses to human life and property.

“Impervious” refers to a hard surface area that retards the entry of water into the soil.

“Land disturbing activity” means any activity that results in a change in the existing soil cover (both vegetative and nonvegetative) and/or the existing soil topography. Land disturbing activities include, but are not limited to, clearing, grading, filling, excavation, and mining. Compaction that is associated with stabilization of structures and road construction shall also be considered a land disturbing activity. Vegetation maintenance practices are not considered land disturbing activity. Stormwater facility maintenance is not considered “land disturbing activity” if conducted according to established standards and procedures.

“Low impact development (LID)” means a stormwater and land use management strategy that strives to mimic predisturbance hydrologic processes of infiltration, filtration, storage, evaporation and transpiration by emphasizing conservation, use of on-site natural features, site planning, and distributed stormwater management practices that are integrated into a project design.

“Lowest floor” means the lowest floor of the lowest enclosed area, including the basement. An unfinished or flood resistant enclosure, usable solely for parking of vehicles, building access, or storage in an area other than a basement area, is not considered a building’s lowest floor; provided, that such enclosure is not built so as to render the structure in violation of the applicable nonelevation design requirements found at BLMC 16.26.060(G)(1)(b); specifically provided, that adequate flood ventilation openings exist.

“Manufactured home” means a structure, transportable in one or more sections, that is built on a permanent chassis and is designed for use with or without a permanent foundation when attached to the required utilities. The term “manufactured home” does not include a recreational vehicle.

“Manufactured home park or subdivision” means a parcel or contiguous parcels of land divided into two or more manufactured home lots for rent or sale.

“Mean sea level” means the National Geodetic Vertical Datum (NGVD) of 1929 or other datum, to which base flood elevations shown on a community’s Flood Insurance Rate Map are referenced.

“Mitigation” means a requirement to replace or enhance critical functions and values destroyed or impacted by proposed land disturbances.

“Monitoring” means assessing the performance of mitigation measures by collection and analysis of data on changes in natural systems.

“Native or equivalent vegetation” means species which are indigenous to the Puget Sound lowlands ecoregion; or a species that is equivalent in providing the same site-specific functional arrays as would the native species. As with natives, the role of an equivalent species may vary depending on the site and its surrounding ecosystem. Invasive/exotic species shall not be considered equivalent species.

“New construction,” for floodplain management purposes only, means structures for which the “start of construction” commenced on or after the effective date of a floodplain management regulation adopted by a community and includes any subsequent improvements to such structures.

“New manufactured home park or subdivision” means a manufactured home park or subdivision for which the construction of facilities for servicing the lots on which the manufactured homes are to be affixed is completed on or after the effective date of this chapter, including, at a minimum, the installation of utilities, the construction of streets, and either final site grading or the pouring of concrete pads.

“No net loss” means the existing functions and values of critical areas are maintained. The no net loss standard requires that the impacts of a proposed use and/or development, whether permitted or exempt from permit requirements, be identified and mitigated on a project-by-project basis, so that as development occurs critical areas functions and values stay the same.

“Ordinary high water mark” means that mark on the bed or bank below which inundation is so common in ordinary years that the soil and/or vegetation are distinct from that of the abutting upland.

“Primary association” means a relationship between a species and a habitat area whereby the species regularly uses or otherwise needs the habitat area to thrive.

“Reasonable use exception” means a grant of relief from the requirements of the critical areas code needed to provide reasonable economic use of the property.

“Reasonably safe from flooding” means development that is designed and built to be safe from flooding based on consideration of current flood elevation studies, historical data, high water marks and other reliable data known to the community. In unnumbered A zones where flood elevation information is not available and cannot be obtained by practicable means, “reasonably safe from flooding” means that the lowest floor is at least two feet above the highest adjacent grade.

“Recreational vehicle” means a vehicle:

1. Built on a single chassis;

2. Four hundred square feet or less when measured at the largest horizontal projection;

3. Designed to be self-propelled or permanently towable by a light duty truck; and

4. Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use.

“Rill” means a small, steep-sided channel caused by erosion.

“Riparian ecosystem” means an area alongside a river or stream that significantly influences exchanges of energy and matter with the aquatic ecosystem. It includes the active channel, the active floodplain and terraces, and portions of the adjacent uplands that contribute organic matter and energy to the active channel or floodplain. It is a zone of influence; a transitional ecotone between terrestrial and aquatic ecosystems that is distinguished by gradients in biophysical conditions, ecological processes, and biota.

Riparian Habitat. See “Riparian ecosystem.”

“Riparian management zone” means a delineable area measured outward in each direction, on the horizontal plane from the floodway; if a floodway has not been determined then the measurement is from the top of the bank, based on the site-potential tree height used to protect riparian ecosystems.

“Site-potential tree height” means the average maximum height of the tallest dominant trees (200 years or more) for a given site class.

“Slope” means an inclined earth surface, the inclination of which is expressed as a percent of vertical distance over horizontal distance (vertical distance/horizontal distance x 100 = %).

“Species” means a group of animals commonly classified by the scientific community as a species or subspecies.

“Start of construction” includes substantial improvement, and means the date the building permit was issued, provided the actual start of construction, repair, reconstruction, placement or other improvement was within 180 days of the permit date. In relation to this term:

1. The “actual start” means either the first placement of permanent construction of a structure on a site, such as the pouring of slab or footings, the installation of piles, the construction of columns, or any work beyond the stage of excavation; or the placement of a manufactured home on a foundation.

2. Permanent construction does not include land preparation, such as clearing, grading and filling; nor does it include the installation of streets and/or walkways; nor does it include excavation for a basement, footings, piers, or foundations or the erection of temporary forms; nor does it include the installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not part of the main structure.

3. For a substantial improvement, the “actual start of construction” means the first alteration of any wall, ceiling, floor, or other structural part of a building, whether or not that alteration affects the external dimensions of the building.

“Structure” means a walled and roofed building, including a gas or liquid storage tank that is principally above ground, as well as a manufactured home.

“Substantial damage” means damage of any origin sustained by a structure for which the cost of restoring the structure to its before-damaged condition would equal or exceed 50 percent of the market value of the structure before the damage occurred.

“Substantial improvement” means any reconstruction, rehabilitation, addition, or improvement of a structure, the cost of which equals or exceeds 50 percent of the market value of the structure before the “start of construction” of the improvement. This term includes structures which have incurred “substantial damage,” regardless of actual repair work performed. The term does not, however, include either:

1. Any project for improvement of a structure to correct previously identified existing violations of state or local health, sanitary, or safety code specifications which have been identified by the local code enforcement official and which are the minimum necessary to assure safe living conditions; or

2. Any alteration of a “historic structure”; provided, that the alteration will not preclude the structure’s continued designation as a “historic structure.”

“Tree topping” means the indiscriminate cutting of branches and laterals to stubs at a specific tree height or spread, often exceeding 25 percent of a tree’s crown mass. Topping is harmful to a tree and creates unsightly regrowth that requires future trimming at frequent intervals.

“Undevelopable critical area” means designated wetlands, streams, fish and wildlife habitat conservation areas, Class 1 landslide hazardous areas, and associated buffers.

“Violation” means the failure of a structure or other development to be fully compliant with the requirements of the city’s critical areas code. A structure or other development without the elevation certificate, other certifications, or other evidence of compliance required by the frequently flooded areas code (Chapter 16.26 BLMC) is presumed to be in violation until such time as that documentation is provided.

“Water surface elevation” means the height, in relation to the National Geodetic Vertical Datum (NGVD) of 1929, or other datum, of floods of various magnitudes and frequencies in the floodplains of coastal or riverine areas.

“Watercourse” means flowing waters of the state, perennial or intermittent, excluding artificial waterways such as ditches or canals not created by human alteration of a natural watercourse.

“Wellhead protection area” or “WHPA” means the zone of contribution associated with an approved public drinking water source as delineated for each well, wellfield, or spring within the six-month and one-, five- and 10-year time-of-travel boundaries marked, or boundaries established using alternate criteria approved by the Washington State Department of Health in those settings where groundwater time of travel is not a reasonable delineation criterion, in accordance with WAC 246-290-135.

“Wetland” or “wetlands” means areas that are inundated or saturated by surface water or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. Wetlands do not include those artificial wetlands intentionally created from nonwetland sites, including, but not limited to, irrigation and drainage ditches, grass-lined swales, canals, detention facilities, wastewater treatment facilities, farm ponds, and landscape amenities, or those wetlands created after July 1, 1990, that were unintentionally created as a result of the construction of a road, street, or highway. Wetlands may include those artificial wetlands intentionally created from nonwetland areas to mitigate conversion of wetlands. (Ord. 1666 § 2, 2021; Ord. 1641 § 5, 2020; Ord. 1615 § 2, 2019; Ord. 1491 § 18, 2014; Ord. 1325 § 6, 2009; Ord. 1301 § 1, 2009; Ord. 1070 § 2, 2004).

16.20.040 Critical areas code.

This chapter establishes the general requirements that apply to all critical areas in addition to the specific requirements in Chapters 16.22, 16.24, 16.26, 16.28 and 16.30 BLMC. The director shall administer and interpret this critical areas code. (Ord. 1615 § 2, 2019; Ord. 1301 § 2, 2009; Ord. 1070 § 2, 2004).

16.20.045 Best available science.

A. Criteria for Best Available Science. The best available science is that scientific information applicable to the critical area prepared by local, state or federal natural resource agencies, a qualified scientific professional or team of qualified scientific professionals consistent with criteria established in WAC 365-195-905 through 365-195-925, as amended.

B. Protection for Functions and Value and Anadromous Fish. Critical area studies and decisions to alter critical areas shall rely on the best available science to protect the functions and value of critical areas and must give special consideration to conservation or protection measures necessary to preserve or enhance anadromous fish and their habitat, such as salmon and bull trout.

C. Absence of Valid Scientific Information. Where there is an absence of valid scientific information or incomplete scientific information relating to a critical area leading to uncertainty about the risk to critical area function of permitting an alteration of or impact to the critical area, the director shall take a “precautionary approach,” that strictly limits development and land use activities until the uncertainty is sufficiently resolved. The burden of proof that the action will cause no net loss or harm to persons or property falls on the applicant or the property owner. (Ord. 1615 § 2, 2019).

16.20.050 Fees.

Chapter 3.68 BLMC establishes fees by which the city shall recover its cost of reviewing development proposals, including the cost of engineering review, planning review, inspections, and administration. The applicant shall be responsible for all required reports, assessments, studies, and plans. (Ord. 1615 § 2, 2019; Ord. 1070 § 2, 2004).

16.20.060 Applicability.

A. Unless exempted in BLMC 16.20.070, this critical areas code shall apply to all developments within one or more of the following critical areas and associated buffers, regardless of whether the site has been previously identified as a critical area:

1. Wetlands as designated in Chapter 16.22 BLMC;

2. Critical aquifer recharge areas as designated in Chapter 16.24 BLMC;

3. Frequently flooded areas as designated in Chapter 16.26 BLMC;

4. Geologically hazardous areas as designated in Chapter 16.28 BLMC; and

5. Fish and wildlife habitat conservation areas as designated in Chapter 16.30 BLMC.

B. When any existing regulation, easement, covenant, or deed restriction conflicts with this critical areas code, that which provides more protection to the critical areas shall apply.

C. All work within a critical area requires a critical areas permit, unless exempted in BLMC 16.20.070. Work exempted in BLMC 16.20.070 shall require approval, as described in BLMC 16.20.070(A) and (B), from the city of Bonney Lake before it is begun. (Ord. 1615 § 2, 2019; Ord. 1301 § 3, 2009; Ord. 1070 § 2, 2004).

16.20.065 Mitigation sequencing.

All proposed development, uses, and activities subject to this chapter shall utilize one or more of the following methods, listed in preferential sequence (commonly known as “sequencing”). The methods used shall be those which are highest on the list yet consistent with the objectives of the proposed development.

A. Avoid the impact altogether by not taking a certain action or parts of an action;

B. Minimize impacts by limiting the action’s magnitude or changing the project design, location, or timing;

C. Rectify the impact by repairing, rehabilitating, or restoring the affected environment;

D. Reduce or eliminate the impact over time by preservation and maintenance operations during the life of the action;

E. Compensate for the impact by replacing, enhancing, or providing substitute resources or environments; and

F. Monitor the impact and take appropriate corrective measures. (Ord. 1615 § 2, 2019).

16.20.070 Exemptions.

All exempted activities shall use reasonable methods to avoid potential impacts to critical areas. To be exempt does not give permission to degrade a critical area or ignore risk from natural hazards. Any incidental damage to, or alteration of, a critical area that is not a necessary outcome of the exempted activity shall be restored, rehabilitated, or replaced at the responsible party’s expense. Exemption from the critical areas code does not exempt an applicant from obtaining all other required permits from the city and/or state agencies.

A. The following activities do not require a written critical area exemption before work is commenced:

1. Normal operation, maintenance, or repair of existing structures, utilities, roads, levees, drainage systems, or similar improvements, including vegetation management, if the action does not modify or increase the impact to or encroach upon the critical area or buffer, and if the action accords with best management practices and maintenance, and does not impact an endangered or threatened species;

2. Passive outdoor activities such as recreation, education, and scientific research that do not degrade the critical area;

3. The following work within improved public rights-of-way or private street easements: construction, replacement, or modification of streets, utilities, lines, mains, equipment, or appurtenances, excluding electrical substations; provided, that actions that modify a wetland or watercourse, such as culverts or bridges, or result in the transport of sediment or increased stormwater shall be subject to the following requirements wherever possible:

a. Critical area and/or buffer widths shall be increased equal to the width of the right-of-way improvement, including disturbed areas; and

b. Native vegetation shall be retained and replanted along the right-of-way improvement;

4. Minor utility projects such as placement of a utility pole, street sign, anchor, or vault, which do not significantly impact critical areas function or values, if constructed using best management practices;

5. Removal with hand labor and light equipment of invasive or noxious plants as designated by the director, including, but not limited to:

a. English ivy (Hedera helix);

b. Himalayan blackberry (Rubus discolor, R. procerus);

c. Evergreen blackberry (Rubus laciniatus); and

d. Weeds listed on the Noxious Weeds Designated for Control or Eradication in Pierce County annual list by the Pierce County noxious weed control board;

6. Minor pruning or thinning of trees may be allowed only if such activity is consistent with the following:

a. The selective removal of branches in the inner crown of the tree, provided no more than 25 percent of a tree’s leaf-bearing crown is removed. An even distribution of interior small branches and foliage on remaining limbs shall be maintained to avoid over-thinning. Creating an unbalanced canopy is prohibited;

b. Work involving the removal of more than 25 percent of a tree’s crown mass shall require a written critical areas exemption and demonstration that the removal is necessary for the clearance of electrical distribution and service lines only;

c. The removal of the lower branches of a tree; provided, that the height of the pruned portion shall not exceed one-third of the total tree height and that removal of branches from the lower portion shall not exceed 25 percent of the tree’s leaf-bearing crown;

d. Tree topping is prohibited;

e. Mature and old-growth trees are more susceptible to permanent damage or death from pruning. Pruning of mature trees should only be done as a corrective or preventative measure, such as the removal of decayed, rubbing, or crowded branches;

7. Application of herbicides, pesticides, or fertilizers, if necessary; provided, that their use shall conform to Department of Fish and Wildlife management recommendations and the regulations of the Department of Agriculture and the U.S. Environmental Protection Agency;

8. Minor clearing or digging necessary for surveys, soil logs, percolation tests, and similar activities, provided critical area impacts are minimized and disturbed areas are immediately restored;

9. Navigational aids and boundary markers;

10. Proposed developments that have undergone critical area review at a previous stage of permit review provided the earlier permit has not expired;

11. Harvesting of wild crops without injuring their natural reproduction, tilling the soil, planting crops, applying chemicals, or altering the critical area;

12. Existing and ongoing agricultural activities where the land has not lain idle so long that modifications to the hydrological regime are necessary to resume operations; and

13. Regular maintenance of existing landscaping regardless of location; provided, that the maintenance does not include the removal of native vegetation.

B. The following activities, while exempt from the critical areas code, require a written critical areas exemption from the city before work is commenced:

1. Emergency actions immediately necessary to prevent injury or property damage, provided the action minimizes impact to critical areas and buffers. The person undertaking the action shall notify the director(s) within one day following commencement of the emergency action. The director(s) shall determine if the action was allowable under this subsection and commence enforcement if not. Within one year of the date of the emergency, the person undertaking the action shall fully mitigate any resulting impacts to the critical area and buffers in accordance with an approved critical area report and mitigation plan;

2. Forest practices in accordance with Chapter 76.09 RCW and WAC Title 222, other than forest practice conversions;

3. Structural modifications of, additions to, or replacements of existing legal structures without altering or increasing the impact to the critical area; provided, that the work complies with city’s regulations regarding legal nonconforming uses and, if applicable, the standards of BLMC 16.26.060. This includes most tenant improvements;

4. Removal of a hazard tree; provided, that removed trees are left on site where appropriate in wetland and habitat areas, and for each tree removed, two replacement trees shall be planted in the same or nearly same location within one year in accordance with a plan approved by the director. The replacement trees shall be of species native and indigenous to the site. Deciduous trees shall be at least one inch in diameter at breast height. Evergreen trees shall be at least six feet in height measured from the top of the root ball. When feasible, wildlife snags shall be created from hazard trees;

5. Measures to control fire or halt the spread of disease or damaging insects consistent with the State Forest Practices Act, Chapter 76.09 RCW; provided, that the removed vegetation shall be replaced with the same or similar native species within one year in accordance with an approved plan;

6. Conservation measures of soil, water, vegetation, fish, and other wildlife that do not adversely impact ecosystems;

7. Required environmental impact remediation; and

8. Development of Category IV wetlands less than 1,000 square feet in size if a critical area report demonstrates that (a) the wetland does not provide suitable habitat for amphibians and (b) the wetland does not possess unique characteristics that would be difficult to replicate. (Ord. 1615 § 2, 2019; Ord. 1070 § 2, 2004).

16.20.080 Review process.

The general sequence for administering this critical areas code shall be per the following table, which shows questions the city shall answer, and actions the city shall take depending on the answer:

Step 1

Does the development proposal contain critical areas or critical area buffers?

The director(s) shall check maps, review the environmental checklist, visit the site, and/or require scientific determinations as necessary to make this determination.



Go to step 2.

Go to step 4.

Step 2

Is the development proposal exempt per BLMC 16.20.070?



Go to step 4.

Require a critical area report. Reference critical area report in any public notice.

Step 3

Does the proposal, with conditions of approval, conform to BLMC 16.20.130, Substantive requirements, the substantive requirements for the critical area type, e.g., wetlands, the permit type processing requirements, and the rest of Bonney Lake Municipal Code?



Go to step 4.

Go to step 4.

Step 4

Document the review process in a manner appropriate to, and filed with, the permit(s) required for the proposed development, and act on the permit application in accordance with the findings. Approval or disapproval and notices of decision shall be issued as required by the appropriate permit type.

(Ord. 1615 § 2, 2019; Ord. 1325 § 7, 2009; Ord. 1070 § 2, 2004).

16.20.090 Critical area reports.

Critical area reports shall be prepared for nonexempt proposed developments containing critical areas or their buffers. In addition to information required in specific critical area chapters, the critical area reports shall:

A. Be prepared by qualified experts as defined in WAC 365-195-905(4). The following list shows the type of critical area report and the related professional discipline:

1. Wetlands: wetland biologist.

2. Critical aquifer recharge areas: hydrogeologist or geologist.

3. Floodplains: hydrologist or engineer.

4. Geologically hazardous areas: engineer or geologist.

5. Fish and wildlife habitats: biologist.

B. Incorporate best available science.

C. Cover a study area large enough to understand relationships with important off-site factors and identify any nearby critical area whose buffer extends onto the project site.

D. Contain the following:

1. Name and contact information of the applicant, description of the proposed development, and identification of required permits;

2. Site plan drawn to scale of no less than one inch equals 100 feet showing critical areas, buffers, existing structures, and proposed structures, clearing, grading, and stormwater management;

3. Characterization of critical areas and buffers;

4. Assessment of the probable impact of the development proposal on critical areas;

5. Analysis of site development alternatives;

6. Detailed explanation of how the project is consistent with each of the sequencing standards identified in BLMC 16.20.065;

7. An analysis of the anticipated impacts on functions and values;

8. Evaluation of compliance with this critical areas code’s substantive requirements applicable to the proposed development;

9. If impacts to the buffer or critical area are proposed the report shall include:

a. A strategy for mitigating the impacts, including site selection factors;

b. An analysis of the existing and anticipated functions and values at the mitigation site, including an assessment of risks; and

c. A review of the best available science relative to the proposed mitigation;

10. Additional information as required in the chapter corresponding to the type of critical area;

11. Documentation of who prepared the report and when, with fieldwork and data sheets;

12. Statement specifying the accuracy of the report and assumptions relied upon;

13. Additional information as required by the director.

E. When the contents of a critical area report determine that a proposed development requires compensatory mitigation and the mitigation approach proposed is acceptable to the city, a separate stand-alone mitigation plan shall be prepared in accordance with BLMC 16.20.110. The mitigation plan will be submitted once the director accepts the findings of the critical area report. (Ord. 1615 § 2, 2019; Ord. 1325 § 8, 2009; Ord. 1070 § 2, 2004).

16.20.100 Previous studies.

Critical area reports may rely upon, without duplication of effort, valid previous studies prepared for the site, taking into account any change in the site, the proposed development, or the surrounding area. (Ord. 1615 § 2, 2019; Ord. 1070 § 2, 2004).

16.20.110 Mitigation plan requirements.

If the city allows conformance with this critical areas code’s substantive requirements to be achieved by mitigation, a mitigation plan shall be submitted. Mitigation should provide equivalent or greater functions and values than those of the critical area and critical area buffer it replaces. The mitigation shall be near the impact site unless it is more cost-effective to mitigate lost functions at a larger scale. The city reserves the right to disallow mitigation that would be located outside the UGA. Components of a mitigation plan shall include:

A. Repealed by Ord. 1615;

B. Repealed by Ord. 1615;

C. Repealed by Ord. 1615;

D. Repealed by Ord. 1615;

E. Repealed by Ord. 1615;

F. Detailed construction plans, including:

1. Construction timing;

2. Grading and excavation details;

3. Erosion and sediment control features;

4. Planting plan including species and spacing; and

5. Measures to protect plants until established and control invasive species;

G. A program for monitoring the mitigation over at least five years;

H. Specific performance standards for evaluating whether the mitigation is successful and potential corrective measures should the monitoring indicate the standards are not being met; and

I. A bond quantity worksheet including the estimated cost of installation, maintenance and monitoring of the mitigation for the duration of the monitoring period. (Ord. 1615 § 2, 2019; Ord. 1070 § 2, 2004).

16.20.115 Financial guarantee.

A. Financial guarantees shall be provided for mitigation required pursuant to this chapter. Financial guarantees shall be sufficient to guarantee that all required mitigation measures will be completed no later than the time established by the city and shall be based on the bond quantity amount established in accordance with BLMC 16.20.110(I). The financial guarantee shall be in a form of an assignment of funds.

B. Depletion, failure or collection of the financial guarantee shall not relieve an applicant or violator from completing the required mitigation, maintenance, monitoring, or restoration as required under this chapter.

C. Public development proposals shall be relieved from having to comply with the provisions of this section if public funds have previously been committed for mitigation, maintenance, monitoring, or restoration. (Ord. 1615 § 2, 2019).

16.20.120 Independent review of critical area report.

The director may have the critical area report evaluated by an independent qualified professional and/or request consultation from an agency with expertise. The cost of the independent review shall be borne by the applicant. If the report and evaluations disagree, the director shall determine which to utilize. (Ord. 1615 § 2, 2019; Ord. 1070 § 2, 2004).

16.20.130 Substantive requirements.

A. Repealed by Ord. 1615.

B. Undevelopable critical areas and associated buffers shall be left undisturbed except as provided below if best management practices are used.

1. The following may be allowed upon approval of a critical areas permit:

a. Authorized functional restoration;

b. In the outer 25 percent of buffers and at least 50 feet from the critical area edge: permeable-surfaced walkways, trails, and minimal wildlife viewing structures; or

c. Other uses and activities specifically authorized by this critical areas code or other activities that will not result in permanent impact on the undevelopable critical areas and associated buffers.

2. Activities in compliance with BLMC 16.20.070.

3. A public agency proposing a public utility or transportation project, where strict application of the critical areas code would prohibit construction of the said public project, may apply for a critical areas permit to request relief from the critical areas code. In order to be granted relief, the public agency shall demonstrate compliance with the following criteria:

a. The project demonstrates compliance with the mitigation sequencing in BLMC 16.20.065;

b. There is no other practical alternative with less impact on the critical areas;

c. The application of the critical area regulations would unreasonably restrict the ability to provide utility services to the public;

d. The public project shall use the best available construction, design, and development techniques that result in the least impact to ecological functions and values of the critical area;

e. Any modification of the required critical areas regulations under this provision shall ensure no net loss of ecological functions and values of the critical area;

f. Mitigation and monitoring shall be provided per BLMC 16.20.110 to address any adverse impacts on critical areas and the associated ecological functions and values; and

g. The public project shall be subject to review under the State Environmental Policy Act (SEPA) and the categorical exemption in WAC 197-11-800(2)(b) through (2)(e), and 197-11-800(23)(a) through (h) shall not apply as authorized by WAC 197-11-908.

4. Developments authorized by a reasonable use exception pursuant to BLMC 16.20.145 for which mitigation is provided per BLMC 16.20.110 and 16.20.115.

C. No development shall occur in a critical area and associated buffer, which results in a net loss of the functions or values of any critical area. The pre- and post-development functional comparison shall be on a per-function basis unless otherwise authorized by this critical areas code.

D. No development shall occur in critical areas and associated buffers which results in an unreasonable hazard to the public health and safety.

E. Where a buffer has been previously established through city review, and is permanently recorded on title or placed within a separate tract, the buffer shall be as previously established, provided it is at least 50 percent of the required standard buffer distance.

F. As a condition of any permit approval for properties with undevelopable critical areas the city shall require that the critical area(s) and/or buffer be placed in a conservation tract or conservation easement, the purpose of which is to set aside and protect the critical area. The conservation tract or conservation easement shall be:

1. Held by the city, a homeowner’s association, a land trust or similar conservation organization, or by each lot owner within the development in an undivided interest;

2. Recorded on all documents of title of record for the affected parcels;

3. Noted on the face of any plat or recorded drawing; and

4. Delineated on the ground with permanent markers and signs in accordance with local survey standards. The outer edge of the critical area or buffer shall be signed and fenced to protect the resource. The director shall specify the design and sign message, if applicable, of such markers, signs, and fencing.

G. As a condition of any permit approval for properties with critical aquifer recharge areas; frequently flooded areas; or erosion, Class 2 landslide, seismic, and/or volcanic hazardous areas, the city:

1. Shall require that the applicant file a notice on title with the Pierce County assessor stating the presence of the critical area or buffer and the application of this critical areas code to the property, to inform subsequent purchasers of the property.

2. May require that the outer edge of the critical area or buffer be signed and/or fenced to protect the resource. The director(s) shall specify the design and sign message, if applicable, of such markers, signs, and fencing.

H. The city may allow averaging of standard buffer widths if a qualified professional demonstrates that:

1. Functions and values are not adversely affected;

2. The total buffer area is not reduced; and

3. At no location is the buffer width reduced by more than 25 percent of the standard buffer width.

I. Where a legally established and constructed road, or other similar transportation infrastructure, transects a wetland buffer or riparian management zone, the city may approve a modification of the standard buffer or riparian management zone width to the edge of the linear feature closest to the critical area if the isolated part of the buffer or riparian management zone does not provide additional protection of the wetland or stream and provides insignificant biological, geological or hydrological functions.

J. Unless otherwise provided, buildings and other structures shall be set back a distance of 10 feet from the edges of all undevelopable critical areas and associated buffers. Protrusions into this setback area shall be allowed consistent with the encroachments allowed into property line setback areas in BLMC Title 18.

K. Lots created through subdivisions or short plats shall not contain undevelopable critical areas and associated buffers. Subdivisions and short plats shall show any applicable critical area limitations.

L. When critical areas of two or more types coincide, the more restrictive buffer and requirements shall apply.

M. The substantive requirements peculiar to the type of critical area shall also be complied with. (Ord. 1649 § 2, 2021; Ord. 1615 § 2, 2019; Ord. 1491 § 19, 2014; Ord. 1252 § 1, 2007; Ord. 1070 § 2, 2004).

16.20.140 Restoration work.

Restoration activity within critical areas may be allowed upon approval of a critical areas permit in one of the following ways:

A. Repealed by Ord. 1615;

B. Native plants in critical areas may be installed; provided, that:

1. Installation of plants on potential landslide hazard areas shall be in accordance with this chapter and Chapter 16.28 BLMC, and may require a geotechnical report that addresses existing slope stability and provide a statement that the proposed planting activity will not likely undermine existing stability;

2. Installation of native plants in wetlands or wetland buffers shall be in accordance with this chapter and Chapter 16.22 BLMC and may require biologists’ or other experts’ reports stating the appropriateness of the proposed plants for the proposed location;

C. Planting within wetlands or their buffers may be used as a future mitigation for other work on or adjacent to the wetland if the following criteria are met:

1. The required wetland report identifies the long-term benefits to the wetland system;

2. The proposed work improves the function and value of a wetland, a buffer, or its system as a natural ecosystem; and

3. The proposed work is carefully monitored with documentation as required in BLMC 16.20.110 and performance bonding required in BLMC 16.20.115. (Ord. 1615 § 2, 2019; Ord. 1325 § 9, 2009; Ord. 1070 § 2, 2004).

16.20.145 Reasonable use exception.

A. If the application of this chapter would deny all reasonable use of the property, the applicant may apply for a reasonable use exception pursuant to this section. Development may be allowed which is consistent with the purpose of this title; provided, the hearing examiner finds that the applicant has demonstrated that all of the following criteria are met:

1. The provisions of this title would deny all reasonable economic use of the property;

2. There is no other reasonable use with less impact on the critical area or its buffer than the use proposed by the applicant;

3. Any alterations to the critical area shall be the minimum necessary to allow for reasonable use of the property;

4. The proposed development does not pose an unreasonable threat to the public health, safety, or welfare on or off the property;

5. The proposal conforms to all other applicable regulations and code provisions;

6. Any impacts permitted to the critical area are mitigated in accordance with BLMC 16.20.065 and 16.20.110 to the greatest extent possible;

7. The need for the exception is not the result of the applicant’s deliberate actions;

8. The exception would not impact anadromous fish habitat;

9. The proposed development protects critical areas and/or buffer functions and values consistent with best available science;

10. The development would not threaten the potability of public drinking water supply(ies); and

11. The application is sufficiently documented (for example, critical area report, mitigation plan, permit applications, and environmental documents) to make a determination regarding these criteria.

B. If the director finds that impact to a critical area or its buffer would be reduced by encroaching into a setback required by BLMC Title 18, the building setback may be reduced by half through the reasonable use exception process.

C. Any authorized alteration of a critical area shall be subject to conditions established by the hearing examiner to safeguard public health, safety, or welfare, to minimize the impact on the critical area and its buffer and further the purpose and goals of this title. (Ord. 1615 § 2, 2019; Ord. 1505 § 16, 2015; Ord. 1325 § 10, 2009).

16.20.150 Enforcement and inspections.

A. In enforcing this critical areas code per Chapter 14.130 BLMC, the director may require a restoration plan prepared by a qualified professional. Historic functions and values, soil configurations, and native vegetation shall be used as a guide for restoration. Flood and geological hazards shall be reduced to the predevelopment level.

B. Reasonable access to the development shall be provided to agents of the city for critical area inspections, monitoring, restoration, or emergency action. (Ord. 1615 § 2, 2019; Ord. 1070 § 2, 2004).

16.20.160 Limited density transfer.

A. Density Calculation. In residential development proposals a portion of the site encumbered by an undevelopable critical area and/or corresponding buffers area can be included in the net acres for the purpose of calculating density; provided, that the proposal does not include any reduction and/or modification in the required standard buffers. This provision does not apply in the conservancy district, which does not use net acres to determine the maximum allowed density.

B. Formula. The calculation of the modified net acre is provided below:

[Net Acre] plus [Undevelopable Area multiplied by the Development Factor] equals Modified Net Acre.

C. Development Factor. The development factor is a number to be used in calculating the number of dwelling units or the maximum allowable floor area for a site which contains undevelopable critical areas. The development factor is derived from the following table:

Undevelopable Environmentally Critical Area as Percentage of Site

Development Factor

1% – 10%


11% – 20%


21% – 30%


31% – 40%


41% – 50%


51% – 60%


61% – 70%


71% – 80%


81% – 90%


91% – 99%


(Ord. 1615 § 2, 2019).

16.20.170 Preexisting developments and uses.

Developments or uses that upon initiation were legally permitted but which do not conform with this critical areas code may continue; except as provided in BLMC 16.24.080. Preexisting developments:

A. Shall not be expanded or changed so as to increase the nonconformity;

B. Shall not be resumed if discontinued for 12 consecutive months; and

C. May be replaced or restored in the event of destruction by fire, explosion, or other casualty only if reconstruction is commenced within one year and completed within 18 months. (Ord. 1615 § 2, 2019; Ord. 1070 § 2, 2004).