For purposes of this chapter, the following definitions shall apply. Other applicable definitions may be located in MCMC Title 14 or elsewhere in the development code.
“Actively farmed”
means land that has a documented history of ongoing agricultural use and that is currently used primarily for the production of crops and/or raising or keeping livestock.
“Adaptive management”
means using scientific methods to evaluate how well regulatory and nonregulatory actions protect the critical area. An adaptive management program is a formal and deliberate scientific approach to taking action and obtaining information in the face of uncertainty.
“Advance mitigation”
means compensation, in the form of creation, re-establishment, rehabilitation, or enhancement, for an anticipated critical area impact that is completed prior to the impact for which it compensates. The compensation must be in accordance with a city-approved plan.
“Agricultural land”
is land primarily devoted to the commercial production of horticultural, viticultural, floricultural, dairy, apiary, or animal products or of berries, grain, hay, straw, turf, seed, Christmas trees not subject to the excise tax imposed by RCW 84.33.100 through 84.33.140, or livestock.
“Alteration”
means any human-induced change in an existing condition of a critical area or its buffer. Alterations include, but are not limited to, grading, filling, channelizing, dredging, clearing (vegetation), draining, construction, compaction, excavation, or any other activity that changes the critical area.
“Anadromous fish”
means those species that migrate up rivers from salt water to spawn in fresh water.
“Aquifer”
means a geological formation, group of formations or part of formation that is capable of yielding a significant amount of water to a well or spring.
“Aquifer recharge areas”
are areas that, due to the presence of certain soils, geology, and surface water, act to recharge ground water by percolation.
“Aquifer susceptibility”
means the ease with which contaminants can move from the land surface to the aquifer based solely on the types of surface and subsurface materials in the area. Susceptibility usually defines the rate at which a contaminant will reach an aquifer unimpeded by chemical interactions with the vadose zone media.
“Aquifer vulnerability”
is the combined effect of susceptibility to contamination and the presence of potential contaminants.
“Artificial wetland or surface water system”
means a wetland or surface water system that was intentionally created from a nonwetland site through human activity and for a specific purpose. This includes stormwater detention ponds, bioswales, irrigation canals, wastewater treatment ponds, landscape amenities, stock ponds, and similar areas.
Artificial wetlands or surface water systems do not include wetlands created as compensation for development impacts or wetlands that have inadvertently become established as a result of changing environmental conditions or land use.
“Best available science”
means information from research, inventory, monitoring, surveys, modeling and assessments that is used to designate, protect, or restore critical areas. As defined by WAC 365-195-900 through 365-195-925, best available science is derived from a process that includes peer reviewed literature, standard methods, quantitative analysis and documented references to produce reliable information.
“Best management practices (BMPs)”
means conservation practices or systems of practices and management measures that:
1. 
Control soil loss and reduce water quality degradation caused by high concentrations of nutrients, animal waste, toxics, and/or sediment;
2. 
Minimize adverse impacts to surface water and ground water flow, circulation patterns, and to the chemical, physical, and biological characteristics of wetlands and streams;
3. 
Protect trees and other vegetation designated to be retained during and following site construction; and
4. 
Provide standards for proper use of chemical herbicides and pesticides within critical areas.
“Buffer” or “buffer area”
means the area or zone contiguous to a critical area that protects the integrity or functions and values of a critical area from potential adverse impacts. Functionally disconnected areas are excluded from buffer areas.
“Channel migration zone”
means the area within which a river or stream channel is likely to move laterally over a specified period (e.g., 100 years).
“City”
means the city of Mill Creek.
“Clearing”
means the removal of timber, brush, grass, ground cover or other vegetative matter from a site, which exposes the earth’s surface of the site.
“Compensatory mitigation”
means replacing, to an equivalent or greater level, critical areas or buffers after all appropriate and practicable impact avoidance and minimization measures have been implemented. Compensatory mitigation includes but is not limited to: wetland creation, rehabilitation, re-establishment, enhancement, and preservation; stream restoration and relocation; and buffer enhancement and restoration.
“Conservation easement”
means a legal agreement or dedication by the property owner to restrict uses of the land. Conservation easements shall be recorded in the Snohomish County real property records, shall run with the land, and are legally binding on all present and future owners of the property.
“Creation”
means the manipulation of a nonwetland (upland) site for purposes of establishing wetland functions and characteristics where none previously existed. Activities could include, but are not limited to, excavation of upland soils to elevations that will produce a wetland hydroperiod, create hydric soils, and support the growth of wetland plant species. Creation results in a net increase in wetland area.
“Critical aquifer recharge area”
means areas designated by WAC 365-190-080(2) that are determined to have a critical recharging effect on aquifers used for potable water as defined by WAC 365-190-030(2).
“Critical area report”
means a report prepared by a qualified professional based on best available science, and the specific methods and standards for technical study required for each applicable critical area. Geotechnical reports and hydrogeological reports are critical area reports specific to geologically hazardous areas and critical aquifer recharge areas, respectively.
“Critical area tract”
means land held in private ownership and retained in an open condition in perpetuity for the protection of critical areas.
“Critical areas”
include any of the following areas or ecosystems: aquifer recharge areas, fish and wildlife habitat conservation areas, frequently flooded areas, geologically hazardous areas, and wetlands, as defined in Chapter 36.70A RCW and this chapter.
“Critical habitat”
means habitat areas with which endangered, threatened, or sensitive plant or wildlife species have a primary association (e.g., feeding, breeding, rearing of young, migrating). Such areas are identified herein with reference to lists, categories, and definitions promulgated by the Washington Department of Fish and Wildlife as identified in WAC 232-12-011 or 232-12-014; in the Priority Habitat and Species (PHS) program of the Department of Fish and Wildlife; or by rules and regulations adopted by the U.S. Fish and Wildlife Service, National Marine Fisheries Service, or any other agency with jurisdiction for such designations.
“Cumulative impacts”
means the combined, incremental effects of human activity on ecological or critical areas functions and values. Cumulative impacts result when the effects of an action are added to or interact with other effects in a particular place and within a particular time. It is the combination of these effects, and any resulting environmental degradation, that should be the focus of cumulative impact analysis and changes to policies and permitting decisions.
“Department”
means the city of Mill Creek department of community development.
“Disturbance”
means alteration (see definition of “alteration”) of a critical area or associated buffer.
“Ditch”
means any graded (manmade) channel specifically installed to collect and convey runoff from properties and roadways. Ditches include drains, outfalls, channels, stormwater runoff facilities or other wholly artificial watercourses, except those that directly result from the manmade modification to a natural watercourse.
“DRASTIC”
means a model developed by the National Water Well Association and Environmental Protection Agency to measure aquifer susceptibility.
“Ecosystem functions”
are the products, physical and biological conditions, and environmental qualities of an ecosystem that result from interactions among ecosystem processes and ecosystem structures. Ecosystem functions include, but are not limited to, sequestered carbon, attenuated peak streamflows, aquifer water level, reduced pollutant concentrations in surface and ground waters, cool summer in-stream water temperatures, and fish and wildlife habitats.
“Ecosystem values”
are the cultural, social, economic, and ecological benefits attributed to ecosystem functions.
“Emergency activities”
are those activities necessary to prevent an immediate threat to public health, safety, or welfare, or that pose an immediate risk of damage to private property and that require remedial or preventative action in a timeframe too short to allow for compliance with the requirements of this chapter.
“Emergent wetland”
means a wetland with at least 30 percent of the surface area covered by erect, rooted, herbaceous vegetation extending above the water surface as the uppermost vegetative stratum.
“Enhancement”
means the manipulation of an existing degraded wetland site to heighten, intensify or improve existing functions or to change the growth stage or composition of the vegetation present. Activities could include, but are not limited to, planting vegetation, controlling non-native or invasive species, modifying site elevations or the proportion of open water to influence plant composition, or some combination of these. Enhancement improves some wetland functions but can lead to a decline in other wetland functions; it does not result in a net increase in wetland area.
“Erosion”
means a process whereby wind, rain, water and other natural agents mobilize and transport soil particles.
“Erosion hazard areas”
means lands or areas underlain by soils identified by the U.S. Department of Agriculture Natural Resource Conservation Service (NRCS) as having “severe” or “very severe” erosion hazards. These include, but are not limited to, Alderwood gravelly sandy loam and Everett gravelly sandy loam soils when they occur on slopes of 15 percent or greater.
“Excavation”
means the mechanical movement or removal of earth.
“Existing and ongoing agricultural activities”
means those activities conducted on lands defined in RCW 84.34.020(2), and those activities involved in the production of crops and livestock, including but not limited to operation and maintenance of existing farm and stock ponds or drainage ditches, irrigation systems, changes between agricultural activities, and maintenance or repair of existing serviceable structures and facilities. Activities that result in the filling of an area or bring an area into agricultural use are not part of an ongoing activity. An operation ceases to be ongoing when the area on which it was conducted has been converted to a nonagricultural use, or has lain idle for more than five years unless that idle land is registered in a federal or state soils conservation program. Forest practices are not included in this definition.
“Exotic”
means any species of plant or wildlife that is not indigenous to the Puget Sound area.
“Fen”
means a type of wetland similar to a bog that is wholly or partly covered with water and dominated by grass-like plants, grasses, and sedges. Fens accumulate peat soil and are alkaline rather than acid.
“Fill material”
means a deposit of earth material.
“Filling”
means the act of transporting or placing by any manual or mechanical means fill material from, to, or on any soil surface, including temporary stockpiling of fill material.
“Fish and wildlife habitat conservation areas”
means areas necessary for maintaining species in suitable habitats within their natural geographic distribution so that isolated subpopulations are not created.
“Fish habitat”
means habitat that is used by fish at any life stage at any time of the year, including potential habitat likely to be used by fish that could be recovered by restoration or management and includes off-channel habitat.
“Flood” or “flooding”
means a general and temporary condition of partial or complete inundation of normally dry land areas from:
1. 
The overflow of inland or tidal waters; and/or
2. 
The unusual and rapid accumulation of runoff of surface waters from any source.
“Floodplain”
means the total land area adjoining a river, stream, watercourse, or lake subject to inundation by the base flood.
“Forested wetland”
means a wetland with at least 30 percent of the surface area covered by woody vegetation greater than 20 feet in height that is at least partially rooted within the wetland.
“Frequently flooded areas”
means lands in the floodplain subject to a one percent or greater chance of flooding in any given year or within areas subject to flooding due to high ground water, and those lands that provide important flood storage, conveyance and attenuation functions, as determined by the director in accordance with WAC 365-190-080(3). Classifications of frequently flooded areas include, at a minimum, the 100-year floodplain designations of the Federal Emergency Management Agency and the National Flood Insurance Program.
“Function assessment” or “functions and values assessment”
means a set of procedures, applied by a qualified professional, to identify the ecological functions being performed in a wetland or other critical area, usually by determining the presence of certain characteristics, and determining how well the critical area is performing those functions. Function assessments can be qualitative or quantitative and may consider social values potentially provided by the wetland or other critical area. Function assessment methods shall be consistent with best available science.
“Functionally and effectively disconnected”
means significant development blocks the protective measures provided by a buffer or RMZ. Significant development includes public infrastructure such as roads and railroads, and private development such as homes or commercial structures. Minor development that does not fully block buffer or RMZ functions includes development such as trails, minor accessory structures, paths, and driveways serving a single residence.
“Functionally disconnected area”
means areas, as determined by the director, that are functionally and effectively disconnected from a wetland or RMZ. The director will evaluate whether the interruption affects the entirety of the buffer or RMZ. Individual structures may not fully interrupt buffer or RMZ function. In such cases, the functionally disconnected area is limited in scope to the portion of the buffer or RMZ that is affected. Where questions exist regarding whether an area is functionally disconnected, or the extent of that impact, the director may require a critical area report.
“Geologically hazardous areas”
means areas that may not be suited to development consistent with public health, safety or environmental standards, because of their susceptibility to erosion, sliding, earthquake, or other geological processes as designated by WAC 365-190-080(4). Types of geologically hazardous areas include: erosion, landslide, and seismic hazards.
“Grading”
means any excavating or filling of the earth’s surface or combination thereof.
“Ground water”
means water in a saturated zone or stratum beneath the surface of land or a surface water body.
“Ground water management area”
means a specific geographic area or subarea designated pursuant to Chapter 173-100 WAC for which a ground water management program is required.
“Ground water management program”
means a comprehensive program designed to protect ground water quality, to assure ground water quantity, and to provide for efficient management of water resources while recognizing existing ground water rights and meeting future needs consistent with local and state objectives, policies and authorities within a designated ground water management area or subarea and developed pursuant to Chapter 173-100 WAC.
“Growth Management Act”
means Chapters 36.70A and 36.70B RCW, as amended, together with administrative regulations adopted thereunder.
“Habitat corridor”
means a vegetated corridor with a minimum width of 100 feet set aside and protected consistent with MCMC § 18.06.830 for preserving connections between wetlands and any of the following:
1. 
A legally protected, relatively undisturbed and vegetated area (e.g., priority habitats, other compensation sites, wildlife areas/refuges, or national, county and state parks where they have management plans with identified areas designated as natural, natural forest, or natural area preserve);
2. 
An area that is the site of a watershed project identified within and fully consistent with a watershed plan, as these terms are defined by RCW 89-08-460;
3. 
An area where development is prohibited per the provisions of a local shoreline master program; or
4. 
An area with equivalent habitat quality that has conservation status in perpetuity, in consultation with the Washington Department of Fish and Wildlife.
“Habitat management”
means management of land to maintain species in suitable habitats within their natural geographic distribution so that subpopulations are not isolated. This does not imply maintaining all habitat or individuals of all species in all cases.
“Hazard tree”
means a tree, or any part of a tree, that is structurally unsound and has a high likelihood of causing damage or injury to persons or property, or otherwise poses a danger to public safety.
“Hazardous substance”
means any liquid, solid, gas, or sludge, including any material, substance, product, commodity, or waste, regardless of quantity, that exhibits any of the physical, chemical or biological properties described in WAC 173-303-090 or 173-303-100.
“High impact land use”
means land uses likely to have a significant adverse impact to critical areas because of the intensity of the use, levels of human activity, use of machinery or chemicals, presence of domesticated animals, or the presence of light and noise. Examples include parking lots; buildings and yard areas of residential, commercial and business park developments; private and public streets; active use parks and recreation facilities; and other uses/activities that are likely to significantly impact critical areas.
“Hydraulic project approval (HPA)”
means a permit issued by the state Department of Fish and Wildlife for modifications to waters of the state in accordance with Chapter 75.20 RCW.
“Hydric soil”
means a soil that is saturated, flooded or ponded long enough during the growing season to develop anaerobic conditions in the upper part. The presence of hydric soil shall be determined following the methods described in the 1987 Corps of Engineers Wetland Delineation Manual (Publication No. Y-87-1) and the Western Mountains, Valleys, and Coast Regional Supplement (Publication No. ERDC/EL TR-10-3).
“Hydrologic soil groups”
means soils grouped according to their runoff-producing characteristics under similar storm and cover conditions. Properties that influence runoff potential are depth to seasonally high water table, intake rate and permeability after prolonged wetting, and depth to a low permeable layer. Hydrologic soil groups are normally used in equations that estimate runoff from rainfall, but can be used to estimate a rate of water transmission in soil. There are four hydrologic soil groups:
1. 
Low runoff potential and a high rate of infiltration potential;
2. 
Moderate infiltration potential and a moderate rate of runoff potential;
3. 
Slow infiltration potential and a moderate to high rate of runoff potential; and
4. 
High runoff potential and very slow infiltration and water transmission rates.
“Hydrophytic vegetation”
means macrophytic plant life growing in water or on a substrate that is at least periodically deficient in oxygen as a result of excessive water content.
“Hyporheic zone”
means the saturated zone located beneath and adjacent to streams that contains some portion of surface waters, serves as a filter for nutrients, and maintains water quality.
“Impervious surface”
means a hard surface area that either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development or that causes water to run off the surface in greater quantities or at an increased rate of flow compared to natural conditions prior to development. Common impervious surfaces include, but are not limited to, roof tops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, and oiled macadam or other surfaces which similarly impede the natural infiltration of stormwater. Impervious surfaces do not include surfaces created through proven low impact development techniques.
“Indigenous”
means any species of plant or wildlife that occurs naturally on a particular site or area.
“Infiltration”
means the downward entry of water into the immediate surface of soil.
“In-kind compensation”
means to replace critical areas with substitute areas whose characteristics and functions closely approximate those destroyed or degraded by a regulated activity.
“In-lieu fee program”
means an agreement between a regulatory agency (state, federal, or local) and a single sponsor, generally a public natural resource agency or nonprofit organization. Under an in-lieu fee agreement, the sponsor collects funds from individuals and/or entities required to conduct compensatory mitigation under a wetland regulatory program. The sponsor uses the funds pooled from multiple permittees to create one or more mitigation sites under the authority of the agreement to satisfy the permittees’ required mitigation.
“Innovative mitigation”
means mitigation that may occur off site and/or may be out of kind compared to the critical area being impacted.
“Isolated wetland”
means a wetland that is not adjacent to or hydraulically connected via surface water, ground water, or other conveyance to another wetland, lake, or stream.
“Lake”
means a naturally existing or artificially created body of standing water, which exists on a year-round basis and occurs in a depression of land or expanded part of a stream. A lake must be greater than one acre in size, greater than six and six-tenths feet in depth at the deepest point, and have less than 30 percent aerial coverage by trees, shrubs, or persistent emergent vegetation. A lake is bounded by the ordinary high water mark or the extension of the elevation of the lake’s ordinary high water mark with the stream where the stream enters the lake.
“Landfill”
means a disposal facility or part of a facility at which solid waste is permanently placed in or on land including facilities that use solid waste as a component of fill.
“Landslide”
means episodic downslope movement of a mass of soil or rock.
“Landslide hazard areas”
means areas that, due to a combination of slope inclination and relative soil permeability, are susceptible to landsliding.
“Light equipment”
means hand-held tools and construction equipment, such as chain saws, wheelbarrows, and post-hole diggers.
“Low impact development”
is a stormwater and land use management strategy that strives to mimic natural hydrologic conditions by emphasizing the pre-disturbance hydrologic processes of infiltration, filtration, storage, evaporation, and transpiration.
“Low impact land use”
means land uses which are not likely to have a significant adverse impact to critical areas because of the intensity of the use, levels of human activity, limited use of machinery or chemicals, site design, and other factors identified in this chapter. Examples include passive open space tracts with low-intensity uses (unpaved trails, hiking, birdwatching, etc.), utility corridors without a maintenance road and little or no vegetation management, cell towers, and detention/retention ponds.
“Mature forested wetland”
means a forested wetland where the largest trees are at least 80 years old or have diameters at breast height of at least 21 inches.
“Mitigation”
means sequentially avoiding impacts, minimizing impacts, or compensating for remaining unavoidable impacts in accordance with MCMC § 18.06.625.
“Monitoring”
means evaluating the impacts of development proposals over time on the biological, hydrological, pedological, and geological elements of such systems and/or assessing the performance of required mitigation measures throughout the collection and analysis of data by various methods for the purpose of understanding and documenting changes in natural ecosystems and features, and includes gathering baseline data.
“Native growth protection area (NGPA)”
means an area where native vegetation is preserved for the purpose of preventing harm to property and the environment, including, but not limited to, controlling surface water runoff and erosion, maintaining slope stability, buffering and protecting plants and animal habitat.
“Native vegetation”
means plant species that are indigenous to the Puget Sound area.
“No net loss”
means the maintenance of the aggregate total of the city’s critical area functions and values as achieved through a case-by-case review of development proposals. Each project shall be evaluated based on its ability to meet the no net loss standard.
“Nonconformity”
means a nonconforming use or nonconforming building as defined in MCMC § 14.01.030(N).
“Off-site compensation”
means to replace critical areas away from the site on which critical area impacts have occurred.
“On-site compensation”
means to replace critical areas at or adjacent to the site on which critical area impacts have occurred.
“Open space land”
means any land area as defined in RCW 84.34.020.
“Ordinary high water mark (OHWM)”
means that mark which is found by examining the bed and banks and ascertaining where the presence and action of waters are so common and usual, and so long continued in all ordinary years, that the soil has a character distinct from that of the abutting upland in respect to vegetation.
“Out-of-kind mitigation”
means replacement of critical areas or buffers with substitute critical areas or buffers whose characteristics do not closely approximate those destroyed or degraded by a regulated activity.
“Permeability”
means the capacity of an aquifer or confining bed to transmit water. It is a property of the aquifer or confining bed and is independent of the force causing movement.
“Permittee-responsible innovative mitigation projects”
means an aquatic resource restoration, establishment, enhancement, and/or preservation activity undertaken by the permittee/applicant/developer (or an authorized agent or contractor) to provide compensatory mitigation for which the permittee/applicant/developer retains full responsibility. This is in contrast to an applicant purchasing credits from a certified mitigation bank.
“Pond”
means a naturally existing or artificially created body of standing water that exists on a year-round basis and occurs in a depression of land or expanded part of a stream. A pond must be less than or equal to one acre and greater than 10,000 square feet in size, and greater than six and six-tenths feet in depth at the deepest point.
“Porous soil types”
means soils, as identified by the National Resources Conservation Service, U.S. Department of Agriculture, which contain voids, pores, interstices or other openings which allow the passing of water.
“Potable water”
means water that is safe and palatable for human use.
“Practical alternative”
means an alternative that is available and capable of being carried out after taking into consideration cost, existing technology, and logistics in light of overall project purposes, and having less impact to critical areas.
“Preservation”
means actions taken to ensure the permanent protection of existing, ecologically important critical areas and/or buffers that the city or another agency has deemed worthy of long-term protection. Preservation includes the implementation of appropriate legal and physical mechanisms such as recording conservation easements and installing protective features such as fences and signs.
“Priority habitat”
means areas with one or more of the following attributes: comparatively high wildlife density; high wildlife species richness; significant wildlife breeding habitat; significant wildlife seasonal ranges; significant movement corridors for wildlife; limited availability; and/or high vulnerability. Priority habitats have unique or significant value to one or more species as classified by the Washington Department of Fish and Wildlife. A priority habitat may consist of a unique vegetation type or dominant plant species, a described successional stage, or a specific structural element under WAC 173-26-020(30).
“Priority species”
means wildlife species of concern due to their population status and their sensitivity to habitat alteration, as defined by the Washington Department of Fish and Wildlife.
“Project area”
means a proposed development site and the lands within 50 feet of the area proposed to be disturbed, altered, or used by the proposed activity.
“Pruning”
means mechanical removal of woody plant parts intended to maintain plant health by removing dead, injured or diseased wood or to control or direct vegetative growth. Pruning in a hillside and associated buffer area is an alteration activity subject to the provisions of this chapter.
“Qualified professional” or “qualified consultant”
shall mean a person with experience and training in the pertinent scientific discipline, and who is a qualified scientific expert with expertise appropriate for the relevant critical area subject in accordance with WAC 365-195-905(4). A qualified professional must have obtained a B.S. or B.A. or equivalent degree in biology, soil science, engineering, environmental studies, fisheries, geomorphology or related field, and two years of related work experience, and meet the following criteria:
1. 
A qualified professional for habitats or wetlands must have a degree in biology or a related discipline and professional experience related to the subject species.
2. 
A qualified professional for geologically hazardous areas must be a professional engineer or geologist, licensed in the state of Washington.
3. 
A qualified professional for critical aquifer recharge areas means a hydrogeologist, geologist, engineer, or other scientist with experience in preparing hydrogeologic assessments.
“Reasonable use exception”
means a mechanism by which the city may grant relief from development code requirements where compliance leaves no reasonable use of a property.
“Recharge”
means the process involved in the absorption and addition of water to ground water.
“Re-establishment”
means the manipulation of a former wetland site with the goal of restoring natural or historic wetland characteristics and functions that are no longer present. Re-establishment activities could include, but are not limited to, grading/excavation, removing fill material, plugging ditches, breaking drain tiles, and planting. Re-establishment results in a net increase in wetland area and functions.
“Regulated activity”
means activities occurring in or near and/or potentially affecting an environmentally critical area or associated buffer that are subject to the provisions of this chapter. Regulated activities generally include but are not limited to any filling, dredging, dumping or stockpiling, draining, excavating, flooding, constructing or reconstructing, driving pilings, obstructing, shading, clearing or harvesting.
“Rehabilitation”
means the manipulation of the physical or hydrological characteristics of an existing degraded wetland for the purposes of repairing natural or historic functions and processes. Activities could involve, but are not limited to, breaching a dike to reconnect wetlands to a floodplain or other activities that restore the natural water regime. Rehabilitation results in a gain in wetland functions and processes but does not result in a net increase in wetland area.
“Repair” or “maintenance”
means an activity that restores the character, scope, size, and design of a serviceable area, structure, or land use to its previously authorized and undamaged condition. Activities that change the character, size, or scope of a project beyond the original design and drain, dredge, fill, flood, or otherwise alter critical areas are not included in this definition.
“Restoration”
means measures taken to restore an altered or damaged natural feature, including:
1. 
Active steps taken to restore damaged wetlands, streams, protected habitat, or their buffers to the functioning condition that existed prior to an unauthorized alteration; and
2. 
Actions performed to re-establish structural and functional characteristics of a critical area that have been lost by alteration, past management activities, or catastrophic events.
“Rills”
means steep-sided channels resulting from accelerated erosion. A rill is generally a few inches deep. Rill erosion tends to occur on slopes, particularly steep slopes with poor vegetative cover.
“Riparian management zone” or “RMZ”
means a stream and the area adjacent to the stream that has the potential to provide full riparian ecosystem functions for a stream, including, but not limited to, bank stability, shade, pollution removal, contributions of detrital nutrients, recruitment of large woody debris, and wildlife habitat. Functionally disconnected areas are excluded from riparian management zones.
“Scrub/shrub wetland”
means a wetland with at least 30 percent of its surface area covered by woody vegetation less than 20 feet in height as the uppermost strata.
“Seismic hazard areas”
means areas that are subject to severe risk of damage as a result of earth-quake-induced ground shaking, slope failure, settlement, or soil liquefaction.
“SEPA”
means the Washington State Environmental Policy Act, Chapter 43.21C RCW.
“Significant habitat”
means areas with one or more of the following attributes: comparatively high wildlife density; high wildlife species diversity; important wildlife nesting or breeding areas; wildlife seasonal ranges or refuge areas along migratory routes; important movement corridors for wildlife; and limited availability or high vulnerability. These areas typically contain some feature that is particularly attractive to wildlife, in most instances water. To be considered a significant habitat, the area must be of sufficient size or functionally linked to another significant habitat or critical habitat to allow continued functioning of the area at the level described in this definition considering existing and proposed developments of non-critical areas in the vicinity.
“Site”
means any parcel or combination of contiguous parcels, or right-of-way or combination of contiguous rights-of-way, under the applicant’s ownership or control.
“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 the ratio of horizontal distance to vertical distance. In these regulations, slopes are generally expressed as a percentage. Percentage of slope refers to a given rise in elevation over a given run or distance. A 40 percent slope, for example, refers to a 40-foot rise in elevation over a distance of 100 feet.
“Slope buffer”
means a designated area contiguous or adjacent to a slope that is required for the continued maintenance, function, and structural stability of the slope.
“Sphagnum bog”
means a type of wetland dominated by mosses that form peat. Sphagnum bogs are very acidic, nutrient-poor systems, fed by precipitation rather than surface inflow, with specially adapted plant communities.
“Stormwater conveyance facilities”
means bioswales, dispersal trenches, stormwater pipes, and other facilities that carry stormwater from a detention or treatment facility to a discharge location.
“Stormwater facility”
means structures or lands used for the specific purpose of treating or managing storm runoff. Stormwater facilities include detention/retention ponds, wet ponds, media filtration facilities, vaults, lagoons, infiltration basins, and other approved facilities constructed in accordance with the city’s stormwater management regulations.
“Stream”
means those areas where surface waters produce a defined channel or bed. A defined channel or bed is an area that demonstrates clear evidence of the passage of water and includes, but is not limited to, bedrock channels, gravel beds, sand and silt beds, and defined-channel swales. The channel or bed need not contain water yearround. Streams provide biological functions and habitat for aquatic organisms. This definition does not include artificially created irrigated ditches, canals, storm or surface water runoff devices or other entirely artificial watercourses unless they are used by anadromous or resident fish populations.
“Structural diversity”
means the relative degree of diversity or complexity of vegetation in a habitat area as indicated by the stratification or layering of different plant communities (e.g., ground cover, shrub layer and tree canopy); the variety of plant species; and the spacing or pattern of vegetation.
“Subdrainage basin” or “subbasin”
means the drainage area of the highest order stream containing the subject property impact area. Stream order is used to define the position of a stream in the hierarchy of tributaries in the watershed. The smallest streams are the highest order (first order) tributaries. These are the upper watershed streams and have no tributaries of their own.
“Surface water systems”
means aquatic resources including lakes, and ponds and riparian management zones.
“Unavoidable”
means adverse impacts that remain after all appropriate and practicable avoidance and minimization measures have been implemented.
“Utility line”
means pipe, conduit, cable or other similar facility by which services are conveyed to the public or individual recipients. Such services shall include, but are not limited to, water supply, electric power with an associated voltage of 55,000 volts or less, natural gas, communications and sanitary sewer.
“Water resources inventory area (WRIA)”
means one of 62 watersheds in the state of Washington, each composed of the drainage areas of a stream or streams, as established in Chapter 173-500 WAC as it existed on January 1, 1997.
“Water table”
means that surface in an unconfined aquifer at which the pressure is atmospheric. The water table is defined by the levels at which water stands in wells that penetrate the aquifer just far enough to hold standing water.
“Waters of the state”
means lakes, rivers, ponds, streams, inland waters, underground waters, salt waters and all other surface waters and water-courses within the jurisdiction of the state of Washington.
“Watershed plan”
means a plan developed by federal, tribal, state, and/or local government agencies and/or appropriate nongovernmental organizations, in consultation with relevant stakeholders, for the specific goal of aquatic resource restoration, establishment, enhancement, and preservation. A watershed plan addresses aquatic resource conditions in the watershed, multiple stakeholder interests, and land uses. Watershed plans may also identify priority sites for aquatic resource restoration and protection. Examples of watershed plans include special area management plans, advance identification programs, and wetland management plans.
“Well”
means a bored, drilled or driven shaft, or a dug hole whose depth is greater than the largest surface dimension for the purpose of withdrawing or injecting water or other liquids.
“Wellhead protection area (WHPA)”
means the portion of a zone of contribution for a well, wellfield or spring, as defined using criteria established by the state Department of Ecology.
“Wetland”
means those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation 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 the conversion of wetlands. For identifying and delineating a wetland, local government shall use the Washington State Wetland Identification and Delineation Manual.
“Wetland buffer”
means a designated area contiguous or adjacent to a wetland that is required for the continued maintenance, function, and structural stability of the wetland.
“Wetland class”
means the general appearance of the wetland based on the dominant vegetative life form or the physiography and composition of the substrate. The uppermost layer of vegetation that possesses an aerial coverage of 30 percent or greater of the wetland constitutes a wetland class. Multiple classes can exist in a single wetland. Types of wetland classes include forest, scrub/shrub, and emergent.
“Wetland edge”
means the boundary of a wetland as delineated based on the definitions contained in this chapter.
“Wetland mitigation bank”
means a site where wetlands and buffers are restored, created, enhanced, or in exceptional circumstances, preserved expressly for the purpose of providing compensatory mitigation in advance of authorized impacts to similar resources.
“Wetlands with special characteristics”
means bogs, estuarine wetlands, forested wetlands, interdunal wetlands, wetlands in coastal lagoons, and wetlands of high conservation value. Detailed information about these individual wetland types is found in the Washington State Wetland Rating System for Western Washington: 2014 Update, Version 2.0 (Publication No. 23-06-009, or as revised).
“Zone of contribution”
means the area surrounding a well or spring that encompasses all areas or features that supply ground water recharge to the well or spring.
(Ord. 2004-603 § 2; Ord. 2006-633 § 2; Ord. 2009-702 § 2 (Exh. C); Ord. 2015-796 § 1; Ord. 2015-803 § 4 (Exh. A); Ord. 2017-814 § 2; Ord. 2026-945 § 2 (Att. A))