Elevation in relation to mean sea level of the lowest floor (including basement) of all structures recorded on a current elevation certificate with Section B completed by the floodplain administrator;

Elevation in relation to mean sea level to which any structure has been floodproofed;

Where a structure is to be floodproofed, certification by a registered professional engineer or architect that the floodproofing methods for any nonresidential structure meet floodproofing criteria in YMC § 18.19.040(B)(2);

Description of the extent to which a watercourse will be altered or relocated as a result of proposed development;

Where development is proposed in a floodway, an engineering analysis indication no rise of the base flood elevation; and

Any other such information that may be reasonably required by the floodplain administrator in order to review the application.

The permit requirements of this chapter have been satisfied;

All other required state and federal permits have been obtained;

The site is reasonably safe from flooding;

The proposed development is not located in the floodway. If located in the floodway, ensure that the encroachment provisions of YMC § 18.19.040(D)(1) are met;

Notify FEMA when annexations occur in the special flood hazard area.

Where base flood elevation data is provided through the FIS, FIRM, or required as in subsection (C)(2) of this section, obtain and maintain a record of the actual (as-built) elevation (in relation to mean sea level) of the lowest floor (including basement) of all new or substantially improved structures, and whether or not the structure contains a basement.

For all new or substantially improved floodproofed nonresidential structures where base flood elevation data is provided through the FIS, FIRM, or as required in subsection (C)(2) of this section:

All new construction and substantial improvements, including those related to manufactured homes, shall be anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads including the effects of buoyancy.

All manufactured homes shall be anchored to prevent flotation, collapse, or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors. For more detailed information, refer to guidebook, FEMA-85, "Manufactured Home Installation in Flood Hazard Areas."

All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.

All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.

Electrical, heating, ventilation, plumbing, and air-conditioning equipment and other service facilities shall be designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the components during conditions of flooding.

The storage or processing of materials that could be injurious to human, animal, or plant life if released due to damage from flooding is prohibited in special flood hazard areas.

Storage of other material or equipment may be allowed if not subject to damage by floods and if firmly anchored to prevent flotation, or if readily removable from the area within the time available after flood warning.

All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the systems;

Water wells shall be located on high ground that is not in the floodway (WAC 173-160-171);

New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharges from the systems into flood waters;

On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

Be consistent with the need to minimize flood damage;

Have public utilities and facilities, such as sewer, gas, electrical, and water systems located and constructed to minimize or eliminate flood damage;

Have adequate drainage provided to reduce exposure to flood damage;

Where subdivision proposals and other proposed developments contain greater than 50 lots or five acres (whichever is the lesser) base flood elevation data shall be included as part of the application.

In AE zones or other A zoned areas where the BFE has been determined or can be reasonably obtained, new construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated one foot or more above the BFE. Mechanical equipment and utilities shall be waterproof or elevated least one foot above the BFE.

New construction and substantial improvement of any residential structure in an A zone for which a BFE is not available and cannot be reasonably obtained shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.

Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs must meet or exceed the following minimum criteria:

New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:

If the requirements of subsection (B)(2)(a) of this section are not met, then new construction and substantial improvement of any commercial, industrial or other nonresidential structure shall meet all of the following requirements:

All manufactured homes to be placed or substantially improved on sites shall be elevated on a permanent foundation such that the lowest floor of the manufactured home and nonfloodproofed utilities serving the manufactured home are elevated one foot or more above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement.

Manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision that are not subject to the above manufactured home provisions shall be elevated so that either:

Be on the site for fewer than 180 consecutive days; or

Be fully licensed and ready for highway use, on wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or

Meet the requirements of subsection (B)(3) of this section.

Detached accessory structures used solely for parking of vehicles or limited storage may be constructed such that the floor is below the BFE, provided the structure is designed and constructed in accordance with the following requirements:

Detached garages, storage structures, and other appurtenant structures not meeting the above standards must be constructed in accordance with all applicable standards in subsection (B)(1) of this section.

Upon completion of the structure, certification that the requirements of this section have been satisfied shall be provided to the floodplain administrator for verification.

If substantially damaged, the substantial damage determination is based only on the cost to repair damage caused by flooding to predamage conditions.

The proposed repair or restoration does not change the size of the structure and does not significantly alter the nature of the building. With the exception of costs associated with wet floodproofing in accordance with subsection (B)(7)(e) of this section, proposals that include work beyond or in addition to that necessary to repair or restore the structure to predamage condition must be regulated as substantial improvements.

The repaired or restored structure will continue to be an agricultural structure, as defined in these regulations.

Owners are notified, in writing, that agricultural structures approved under this section:

Wet Floodproofing Construction Requirements. When owners elect to wet floodproof flood-damaged agricultural structures as part of repair or restoration to predamage condition, the structure shall:

Replacement of Farmhouses in Floodway. Repairs, reconstruction, replacement, or improvements to existing farmhouse structures located in designated floodways and that are located on lands designated as agricultural lands of long-term commercial significance under RCW 36.70A.170 may be permitted subject to the following:

Substantially Damaged Residences in Floodway.

Variances shall not be issued within any floodway if any increase in flood levels during the base flood discharge would result;

Upon a determination that the variance is the minimum necessary, considering the flood hazard, to afford relief;

Upon a showing of good and sufficient cause;

Upon a determination that failure to grant the variance would result in exceptional hardship to the applicant;

Upon a determination that the granting of a variance will not result in increased flood heights, additional threats to public safety, extraordinary public expense, create nuisances, cause fraud on or victimization of the public, or conflict with existing state laws or local ordinances.

Upon a showing that the use cannot perform its intended purpose unless it is located or carried out in close proximity to water. This includes only facilities defined in Chapter 18.02 YMC in the definition of "functionally dependent use." In order to approve a variance for a functionally dependent use, the criteria in subsection (A)(1) of this section must be met.

For the repair, rehabilitation, or restoration of historic structures upon a determination that the proposed repair or rehabilitation will not preclude the structure's continued designation as a historic structure and the variance is the minimum necessary to preserve the historic character and design of the structure. In order to approve a variance for the repair, rehabilitation, or restoration of a historic structure, the criteria in subsection (A)(1) of this section must be met.

Accessory Structures and Agricultural Structures. A variance is authorized to be issued for the construction or substantial improvement of accessory structures and agricultural structures, provided the requirements of this section and the following are satisfied:

The danger that materials may be swept onto other lands to the injury of others;

The danger to life and property due to flooding or erosion damage;

The susceptibility of the proposed facility and its contents to flood damage and the effect of such damage on the individual owner;

The importance of the services provided by the proposed facility to the community;

The necessity to the facility of a waterfront location, where applicable;

The availability of alternative locations for the proposed use which are not subject to flooding or erosion damage;

The compatibility of the proposed use with existing and anticipated development;

The relationship of the proposed use to the comprehensive plan and floodplain management program for that area;

The safety of access to the property in times of flood for ordinary and emergency vehicles;

The expected heights, velocity, duration, rate of rise, and sediment transport of the floodwaters and the effects of wave action, if applicable, expected at the site; and

The cost of providing governmental services during and after flood conditions, including maintenance and repair of public utilities and facilities such as sewer, gas, electrical, and water systems, and streets and bridges.

Wetlands;

Critical aquifer recharge areas;

Frequently flooded areas;

Geologically hazardous areas; and

Fish and wildlife habitat conservation areas.

On a site immediately adjoining a critical area;

A distance equal to or less than the required critical area buffer width and building setback;

A distance equal to or less than one-half mile (2,640 feet) from a bald eagle nest;

A distance equal to or less than 300 feet upland from a stream, wetland, or water body;

Within a frequently flooded area; or

A distance equal to or less than 200 feet from a critical aquifer recharge area.

Address funding for the research component of the adaptive management program;

Change course based on the results and interpretation of new information that resolves uncertainties; and

Commit to the appropriate time frame and scale necessary to reliably evaluate regulatory and nonregulatory actions affecting protection of critical areas and anadromous fisheries.

Active steps to restore damaged wetlands, streams, protected habitat, or their buffers to the functioning condition that existed prior to an unauthorized alteration, and

Actions performed to reestablish structural and functional characteristics of the critical area that have been lost by alteration, past management activities, or catastrophic events.

The provisions of this chapter have been previously addressed as part of another approval;

There have been no material changes in the potential impact to the critical area or buffer since the prior review;

There is no new information available that is applicable to any critical area review of the site or particular critical area;

The permit or approval has not expired or, if no expiration date, no more than five years have elapsed since the issuance of that permit or approval; and

Compliance with any standards or conditions placed upon the prior permit or approval has been achieved or secured;

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

Retention and replanting of native vegetation shall occur wherever possible along the right-of-way improvement and resulting disturbance. Native vegetation includes plant species that are indigenous to the area in question; and

Removal of invasive species.

There is no practical alternative to the proposed activity with less impact on critical areas;

The activity involves the placement of a utility pole, street signs, anchor, or vault or other small component of a utility facility; and

The activity involves disturbance of an area less than 75 square feet;

The trail surface shall meet all other requirements including water quality standards set forth in the [locally adopted stormwater management regulations];

Critical area and/or buffer widths shall be increased, where possible, equal to the width of the trail corridor, including disturbed areas; and

Trails proposed to be located in landslide or erosion hazard areas shall be constructed in a manner that does not increase the risk of landslide or erosion and in accordance with an approved geotechnical report;

The removal of the following vegetation with hand labor, light equipment or regulated grazing:

The removal of trees from critical areas and buffers that are hazardous, posing a threat to public safety or posing an imminent risk of damage to private property; provided, that:

Measures to control a 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 in-kind or with similar native species within one year in accordance with an approved restoration plan; and

Unless otherwise provided, or as a necessary part of an approved alteration, removal of any vegetation or woody debris from a habitat conservation area or wetland shall be prohibited;

Category I. Category I wetlands are those that:

Category II. Category II wetlands are difficult, though not impossible, to replace, and provide high levels of some functions. Category II wetlands in western Washington include wetlands scoring between 51 and 69 points in the 2004 rating system.

Category III. Category III wetlands are those with a moderate level of functions (scores between 30 and 50 points). Wetlands scoring between 30 and 50 points generally have been disturbed in some ways and are often less diverse or more isolated from other natural resources in the landscape than Category II wetlands.

Category IV. Category IV wetlands have the lowest levels of functions (scores less than 30 points) and are often heavily disturbed.

Wetland delineation and required buffers;

Existing wetland acreage;

Wetland category;

Vegetative, faunal, and hydrologic characteristics;

Soil and substrate conditions;

Topographic elevations, at two-foot contours; and

A discussion of the water sources supplying the wetland and documentation of hydrologic regime (locations of inlet and outlet features, water depths throughout the wetland, evidence of recharge or discharge, evidence of water depths throughout the year: drift lines, algal layers, moss lines, and sediment deposits).

Existing and proposed wetland acreage;

Vegetative and faunal conditions;

Surface and subsurface hydrologic conditions including an analysis of existing and future hydrologic regime and proposed hydrologic regime for enhanced, created, or restored mitigation areas;

Relationships within watershed and to existing water bodies;

Soil and substrate conditions, topographic elevations;

Existing and proposed adjacent site conditions;

Required wetland buffers (including any buffer reduction and mitigation proposed to increase the plant densities, remove weedy vegetation, and replant the buffers);

Property ownership; and

Associated wetlands and related wetlands that may be greater than 300 feet from the subject project.

Water-dependent activities may be allowed where there are no practicable alternatives that would have a less adverse impact on the wetland, its buffers and other critical areas.

Where non-water-dependent activities are proposed, it shall be presumed that alternative locations are available, and activities and uses shall be prohibited, unless the applicant demonstrates that:

Standard Buffer Widths. The standard buffer widths presume the existence of a relatively intact native vegetation community in the buffer zone adequate to protect the wetland functions and values at the time of the proposed activity. If the vegetation is inadequate, then the buffer width shall be increased or the buffer should be planted to maintain the standard width. Required standard wetland buffers, based on wetland category and land use intensity, are as follows:

Measurement of Wetland Buffers. All buffers shall be measured from the wetland boundary as surveyed in the field. The width of the wetland buffer shall be determined according to the wetland category and the proposed land use. The buffer for a wetland created, restored, or enhanced as compensation for approved wetland alterations shall be the same as the buffer required for the category of the created, restored, or enhanced wetland. Only fully vegetated buffers will be considered. Lawns, walkways, driveways, and other mowed or paved areas will not be considered buffers.

Increased Wetland Buffer Widths. The administrator shall require increased buffer widths in accordance with the recommendations of an experienced, qualified professional wetland scientist, and the best available science on a case-by-case basis when a larger buffer is necessary to protect wetland functions and values based on site-specific characteristics. This determination shall be based on one or more of the following criteria:

Wetland Buffer Width Averaging. The administrator may allow modification of the standard wetland buffer width in accordance with an approved critical area report and the best available science on a case-by-case basis by averaging buffer widths. Averaging of buffer widths may only be allowed where a qualified professional wetland scientist demonstrates that:

Buffer Consistency. All mitigation sites shall have buffers consistent with the buffer requirements of this chapter.

Buffer Maintenance. Except as otherwise specified or allowed in accordance with this chapter, wetland buffers shall be retained in an undisturbed or enhanced condition. Removal of invasive nonnative weeds is required for the duration of the mitigation bond.

Buffer Uses. The following uses may be permitted within a wetland buffer in accordance with the review procedures of this chapter; provided they are not prohibited by any other applicable law and they are conducted in a manner so as to minimize impacts to the buffer and adjacent wetland:

Avoiding the impact altogether by not taking a certain action or parts of an action.

Minimizing impacts by limiting the degree or magnitude of the action and its implementation, by using appropriate technology, or by taking affirmative steps to avoid or reduce impacts.

Rectifying the impact by repairing, rehabilitating, or restoring the affected environment.

Reducing or eliminating the impact over time by preservation and maintenance operations.

Compensating for the impact by replacing, enhancing, or providing substitute resources or environments.

The lost wetland provides minimal functions as determined by a site-specific function assessment, and the proposed compensatory mitigation action(s) will provide equal or greater functions or will provide functions shown to be limiting within a watershed through a formal Washington State watershed assessment plan or protocol; or

Out-of-kind replacement will best meet formally identified watershed goals, such as replacement of historically diminished wetland types.

Restoring wetlands on upland sites that were formerly wetlands.

Creating wetlands on disturbed upland sites such as those with vegetative cover consisting primarily of nonnative introduced species. This should only be attempted when there is a consistent source of hydrology and it can be shown that the surface and subsurface hydrologic regime is conducive for the wetland community that is being designed.

Enhancing significantly degraded wetlands in combination with restoration or creation. Such enhancement should be part of a mitigation package that includes replacing the impacted area meeting appropriate ratio requirements.

There are no reasonable on-site or in-subdrainage basin opportunities or on-site and in-subdrainage basin opportunities do not have a high likelihood of success, after a determination of the natural capacity of the site to mitigate for the impacts. Consideration should include: anticipated wetland mitigation replacement ratios, buffer conditions and proposed widths, hydrogeomorphic classes of on-site wetlands when restored, proposed flood storage capacity, potential to mitigate riparian fish and wildlife impacts (such as connectivity);

Off-site mitigation has a greater likelihood of providing equal or improved wetland functions than the impacted wetland; and

Off-site locations shall be in the same subdrainage basin unless:

Acreage Replacement Ratios. The following ratios shall apply to creation or restoration that is in kind, is on site, is the same category, is timed prior to or concurrent with alteration, and has a high probability of success. These ratios do not apply to remedial actions resulting from unauthorized alterations; greater ratios shall apply in those cases. These ratios do not apply to the use of credits from a state certified wetland mitigation bank. When credits from a certified bank are used, replacement ratios should be consistent with the requirements of the bank's certification. The first number specifies the acreage of replacement wetlands and the second specifies the acreage of wetlands altered.

Increased Replacement Ratio. The administrator may increase the ratios under the following circumstances:

Proposed mitigation will result in a lower category wetland or reduced functions relative to the wetland being impacted; or

The impact was an unauthorized impact.

Impacts to wetland functions may be mitigated by enhancement of existing significantly degraded wetlands, but must be used in conjunction with restoration and/or creation. Applicants proposing to enhance wetlands must produce a critical area report that identifies how enhancement will increase the functions of the degraded wetland and how this increase will adequately mitigate for the loss of wetland area and function at the impact site. An enhancement proposal must also show whether existing wetland functions will be reduced by the enhancement actions.

At a minimum, enhancement acreage shall be double the acreage required for creation or restoration. The ratios shall be greater than double the required acreage where the enhancement proposal would result in minimal gain in the performance of wetland functions and/or result in the reduction of other wetland functions currently being provided in the wetland.

Mitigation ratios for enhancement in combination with other forms of mitigation shall range from 6:1 to 3:1 and be limited to Class III and Class IV wetlands.

Located outside of the wetland and its buffer; and

Meets the minimum lot size requirements of [locally adopted zoning dimensions].

Underground Tanks. All new underground storage facilities proposed for use in the storage of hazardous substances or hazardous wastes shall be designed and constructed so as to:

Aboveground Tanks. All new aboveground storage facilities proposed for use in the storage of hazardous substances or hazardous wastes shall be designed and constructed so as to:

Vehicle repair and servicing must be conducted over impermeable pads and within a covered structure capable of withstanding normally expected weather conditions. Chemicals used in the process of vehicle repair and servicing must be stored in a manner that protects them from weather and provides containment should leaks occur.

No dry wells shall be allowed in critical aquifer recharge areas on sites used for vehicle repair and servicing. Dry wells existing on the site prior to facility establishment must be abandoned using techniques approved by the state Department of Ecology prior to commencement of the proposed activity.

Use of reclaimed water for surface percolation must meet the ground water recharge criteria given in RCW 90.46.010(10) and 90.46.080(1). The State Department of Ecology may establish additional discharge limits in accordance with RCW 90.46.080(2).

Direct injection must be in accordance with the standards developed by authority of RCW 90.46.042.

Construction of new critical facilities shall be permissible within frequently flooded areas if no feasible alternative site is available.

Critical facilities constructed within frequently flooded areas shall have the lowest floor elevated three feet or more above the level of the base flood elevation (100-year flood).

Floodproofing and sealing measures must be taken to ensure that toxic substances will not be displaced by or released into flood waters.

Access routes elevated to or above the level of the base flood elevation shall be provided to all critical facilities to the extent possible.

Areas of historic failures;

Areas with all three of the following characteristics:

Areas that have shown movement during the Holocene epoch (from 10,000 years ago to the present) or that are underlain or covered by mass wastage debris of that epoch;

Slopes that are parallel or subparallel to planes of weakness (such as bedding planes, joint systems, and fault planes) in subsurface materials;

Slopes having gradients steeper than 80 percent, subject to rock fall during seismic shaking;

Areas potentially unstable because of rapid stream incision, streambank erosion, and undercutting by wave action;

Areas that show evidence of or are at risk from snow avalanches;

Areas located in a canyon or on an active alluvial fan, presently or potentially subject to inundation by debris flows or catastrophic flooding; and

Any area with a slope of 40 percent or steeper and with a vertical relief of 10 or more feet, except areas composed of consolidated rock. A slope is delineated by establishing its toe and top and is measured by averaging the inclination over at least 10 feet of vertical relief.

The magnitude of an earthquake;

The distance from the source of an earthquake;

The type of thickness of geologic materials at the surface; and

The type of subsurface geologic structure.

Will not increase the threat of the geological hazard to adjacent properties beyond pre-development conditions;

Will not adversely impact other critical areas;

Are designed so that the hazard to the project is eliminated or mitigated to a level equal to or less than pre-development conditions; and

Are certified as safe as designed and under anticipated conditions by a qualified engineer or geologist, licensed in the state of Washington.

Minimum Buffer. The minimum buffer shall be equal to the height of the slope.

Buffer Reduction. The buffer may be reduced to a minimum of 10 feet when a qualified professional demonstrates to the administrator's satisfaction that the reduction will adequately protect the proposed development, adjacent developments and uses, and the subject critical area.

Increased Buffer. The buffer may be increased where the administrator determines a larger buffer is necessary to prevent risk of damage to proposed and existing development.

The development will not increase surface water discharge or sedimentation to adjacent properties beyond pre-development conditions;

The development will not decrease slope stability on adjacent properties; and

Such alterations will not adversely impact other critical areas.

Land that is located wholly within a landslide hazard area or its buffer may not be subdivided. Land that is located partially within a landslide hazard area or its buffer may be divided; provided, that each resulting lot has sufficient buildable area outside of, and will not affect, the landslide hazard or its buffer.

Access roads and utilities may be permitted within the landslide hazard area and associated buffers if the city determines that no other feasible alternative exists; and

Areas with which state or federally designated endangered, threatened, and sensitive species have a primary association;

State Priority Habitats and Areas Associated with State Priority Species. Priority habitats and species are considered to be priorities for conservation and management. Priority species require protective measures for their perpetuation due to their population status, sensitivity to habitat alteration, and/or recreational, commercial, or tribal importance. Priority habitats are those habitat types or elements with unique or significant value to a diverse assemblage of species. A priority habitat may consist of a unique vegetation type or dominant plant species, a described successional stage, or a specific structural element. Priority habitats and species are identified by the state Department of Fish and Wildlife.

Naturally Occurring Ponds under 20 Acres. Naturally occurring ponds are those ponds under 20 acres and their submerged aquatic beds that provide fish or wildlife habitat, including those artificial ponds intentionally created from dry areas in order to mitigate impacts to ponds. Naturally occurring ponds do not include ponds deliberately designed and created from dry sites, such as canals, detention facilities, wastewater treatment facilities, farm ponds, temporary construction ponds, and landscape amenities, unless such artificial ponds were intentionally created for mitigation.

Waters of the State. Waters of the state include lakes, rivers, ponds, streams, inland waters, underground waters, salt waters, and all other surface waters and watercourses within the jurisdiction of the state of Washington.

Areas of Rare Plant Species and High Quality Ecosystems. Areas of rare plant species and high quality ecosystems are identified by the Washington State Department of Natural Resources through the Natural Heritage Program.

Land useful or essential for preserving connections between habitat blocks and open spaces.

Establishment of buffer zones;

Preservation of critically important vegetation and/or habitat features such as snags and downed wood;

Limitation of access to the habitat area, including fencing to deter unauthorized access;

Seasonal restriction of construction activities;

Establishment of a duration and timetable for periodic review of mitigation activities; and

Requirement of a performance bond, when necessary, to ensure completion and success of proposed mitigation.

Establishment of Buffers. The administrator shall require the establishment of buffer areas for activities adjacent to habitat conservation areas when needed to protect habitat conservation areas. Buffers shall consist of an undisturbed area of native vegetation or areas identified for restoration established to protect the integrity, functions, and values of the affected habitat. Required buffer widths shall reflect the sensitivity of the habitat and the type and intensity of human activity proposed to be conducted nearby and shall be consistent with the management recommendations issued by the Washington Department of Fish and Wildlife. Habitat conservation areas and their buffers shall be preserved in perpetuity through the use of native growth protection areas and critical area tracts. Native growth protection areas includes 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.

Seasonal Restrictions. When a species is more susceptible to adverse impacts during specific periods of the year, seasonal restrictions may apply. Larger buffers may be required and activities may be further restricted during the specified season.

Habitat Buffer Averaging. The administrator may allow the recommended habitat area buffer width to be reduced in accordance with a critical area report, the best available science, and the management recommendations issued by the Washington Department of Fish and Wildlife, only if:

Land that is located wholly within a habitat conservation area or its buffer may not be subdivided.

Land that is located partially within a habitat conservation area or its buffer may be divided; provided, that the developable portion of each new lot and its access is located outside of the habitat conservation area or its buffer and meets the minimum lot size requirements.

Access roads and utilities serving the proposed may be permitted within the habitat conservation area and associated buffers only if the city determines that no other feasible alternative exists and when consistent with this chapter.

No development shall be allowed within a habitat conservation area or buffer with which state or federally endangered, threatened, or sensitive species have a primary association, except that which is provided for by a management plan established by the Washington Department of Fish and Wildlife or applicable state or federal agency.

Whenever activities are proposed adjacent to a habitat conservation area with which state or federally endangered, threatened, or sensitive species have a primary association, such area shall be protected through the application of protection measures in accordance with a critical area report prepared by a qualified professional and approved by the city. Approval for alteration of land adjacent to the habitat conservation area or its buffer shall not occur prior to consultation with the Washington Department of Fish and Wildlife for animal species, the Washington State Department of Natural Resources for plant species, and other appropriate federal or state agencies.

Bald eagle habitat shall be protected pursuant to the Washington State Bald Eagle Protection Rules WAC 232-12-292. Whenever activities are proposed adjacent to a verified nest territory or communal roost, a habitat management plan shall be developed by a qualified professional. Activities are adjacent to bald eagle sites when they are within 800 feet or within one-half mile (2,640 feet) and in a shoreline foraging area. The city shall verify the location of eagle management areas for each proposed activity. Approval of the activity shall not occur prior to approval of the habitat management plan by the Washington Department of Fish and Wildlife.

Establishment of Riparian Habitat Areas. Riparian habitat areas shall be established for habitats that include aquatic and terrestrial ecosystems that mutually benefit each other and that are located adjacent to rivers, perennial or intermittent streams, seeps, and springs.

A riparian habitat area width of 150 feet is established along Yelm Creek and Thompson Creek, both Type 5, intermittent streams with low mass wasting potential as defined in WAC 222-16-031.

Increased Riparian Habitat Area Widths. The recommended riparian habitat area widths shall be increased, as follows:

Riparian Habitat Area Width Averaging. The administrator may allow the recommended riparian habitat area width to be reduced in accordance with a critical area report only if:

Riparian Habitat Mitigation. Mitigation of adverse impacts to riparian habitat areas shall result in equivalent functions and values on a per function basis, be located as near the alteration as feasible, and be located in the same subdrainage basin as the habitat impacted.

Alternative Mitigation for Riparian Habitat Areas. The performance standards set forth in this subsection may be modified at the city's discretion if the applicant demonstrates that greater habitat functions, on a per function basis, can be obtained in the affected subdrainage basin as a result of alternative mitigation measures.

Clearing and Grading. When clearing and grading is permitted as part of an authorized activity or as otherwise allowed in these standards, the following shall apply:

Shoreline Erosion Control Measures. New, replacement, or substantially improved shoreline erosion control measures may be permitted in accordance with an approved critical area report that demonstrates the following:

Streambank Stabilization. Streambank stabilization to protect new structures from future channel migration is not permitted except when such stabilization is achieved through bioengineering or soft armoring techniques in accordance with an approved critical area report.

Roads, Trails, Bridges, and Rights-of-Way. Construction of trails, roadways, and minor road bridging, less than or equal to 30 feet wide, may be permitted in accordance with an approved critical area report subject to the following standards:

Utility Facilities. New utility lines and facilities may be permitted to cross watercourses in accordance with an approved critical area report if they comply with the following standards:

Public Flood Protection Measures. New public flood protection measures and expansion of existing ones may be permitted, subject to the city's review and approval of a critical area report and the approval of a federal biological assessment by the federal agency responsible for reviewing actions related to a federally listed species.

Instream Structures. Instream structures, such as, but not limited to, high-flow bypasses, sediment ponds, instream ponds, retention and detention facilities, tide gates, dams, and weirs, shall be allowed only as part of an approved watershed basin restoration project approved by the city and upon acquisition of any required state or federal permits. The structure shall be designed to avoid modifying flows and water quality in ways that may adversely affect habitat conservation areas.

Stormwater Conveyance Facilities. Conveyance structures may be permitted in accordance with an approved critical area report subject to the following standards:

On-Site Sewage Systems and Wells.