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A. All significant adverse impacts to wetlands and buffers as determined by the City Planner shall be fully mitigated in accordance with the standards in this section and a mitigation plan consistent with this section. Mitigation measures to be addressed in the mitigation plan shall include, in order of preference, avoidance, minimization, restoration, rehabilitation, and compensation.

B. Mitigation for alterations to wetlands may be by restoring former wetlands, creating wetlands, or enhancing degraded wetlands, consistent with the Department of Ecology Guidance on Wetland Mitigation in Washington State, Part 2 (Ecology Publication #04-06-013B).

C. Mitigation shall generally replace wetland functions lost from the altered wetland except that the City may permit out-of-kind replacement when the lost functions are minimal or less important to the drainage basin than the functions that the mitigation action seeks to augment.

D. Mitigation shall be in the same drainage basin or sub-basin as the altered wetland, unless a higher level of ecological functioning would result from an alternate approach.

E. Mitigation projects shall be completed as quickly as possible, consistent with such factors as rainfall and seasonal sensitivity of fish, wildlife, and flora, and shall be completed no later than the first year following completion of the development project.

F. Mitigation projects shall be designed with reference to the Department of Ecology’s Guidance on Wetland Mitigation in Washington State, Part 2 (Ecology Publication #04-06013B) and Appendix 8-C of the Department of Ecology’s Wetlands in Washington - Volume 2: Guidance for Protecting and Managing Wetlands (Ecology Publication #04-06-024).

G. Mitigation for alterations to wetlands shall achieve equivalent or greater biologic functions and shall provide similar wetland functions as those lost, except when:

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

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

H. Compensation in the form of wetland creation, restoration or enhancement is required when a wetland is altered permanently as a result of an approved project. Alterations shall not result in net loss of wetland area, except when compensation for wetland alterations is provided in the following order of preference:

1. Wetlands are restored on upland sites that were formerly wetlands.

2. Wetlands are created on disturbed upland sites such as those with vegetative cover consisting primarily of exotic introduced species.

I. Mitigation actions shall be conducted within the same sub-drainage basin and on the same site as the alteration except when all of the following apply:

1. Either there are no reasonable on-site or in-sub-drainage basin opportunities, or on-site and in-sub-drainage basin opportunities do not have a high likelihood of success due to development pressures, adjacent land uses, or on-site buffers or connectivity are inadequate.

2. Off-site mitigation has a greater likelihood of providing equal or improved wetland functions than the altered wetland.

3. Where feasible, mitigation projects shall be completed prior to activities that will disturb wetlands. In all other cases, mitigation shall be completed immediately following disturbance and prior to use or occupancy of the activity or development.

4. Construction of mitigation projects shall be timed to reduce impacts to existing wildlife and vegetation.

5. The applicant shall develop a mitigation plan that provides for construction, maintenance, monitoring, contingencies and adaptive management of the wetland compensation projects, as required by conditions of approval and consistent with the requirements of this chapter.

J. Wetland mitigation – Replacement ratios

1. When an applicant proposes to alter or eliminate a regulated wetland, the functions and values of the affected wetland and buffer shall be replaced through wetland creation, restoration, or enhancement, according to the minimum ratios established in the table in this section. The ratios shall apply to wetland creation, restoration, or enhancement, which is in-kind, on-site, of the same category, timed prior to or concurrent with alteration, and has a high probability of success.

2. Ratios for out-of-kind or off-site mitigation may be greater than set forth in the table, if the City Planner determines that additional mitigation is warranted to mitigate impacts. Ratios for remedial actions resulting from unauthorized alterations shall be greater than set forth in the table, provided that the extent of the increase shall be as determined by the City Planner to be appropriate in the circumstances.

3. Replacement ratios may be decreased by up to 25 percent by the City Planner, if the applicant demonstrates to the satisfaction of the City Planner that all of the following criteria are met:

a. Documentation by a qualified professional demonstrates that the proposed mitigation actions have a very high likelihood of success;

b. Documentation by a qualified professional demonstrates that the proposed mitigation actions will provide functions and values that are significantly greater than the wetland being altered;

c. The proposed mitigation actions are conducted in advance of the impact and shown to be successful through post-construction monitoring and function assessment.

4. The mitigation ratios in the following table are based on Appendix 8-C of the Department of Ecology’s Wetlands in Washington - Volume 2: Guidance for Protecting and Managing Wetlands (Ecology Publication #04-06-024):

Acreage-Based Mitigation Ratios Table

Affected Wetland

Mitigation Type and Ratio

Category

Reestablishment or Wetland Creation

Rehabilitation

Reestablishment or Creation (R/C) and Enhancement (E)

Enhancement Only

Category IV

1.5:1

3:1

1:1 R/C and 2:1 E

6:1

Category III

2:1

4:1

1:1 R/C and 2:1 E

8:1

Category II

3:1

6:1

1:1 R/C and 4:1 E

12:1

Category I - Forested

6:1-

12:1

1:1 R/C

10:1 Enhancement

24:1

Category I - Score Based

4:1-

8:1

1:1 R/C 10:1 Enhancement

16:1

Category I - Bog

Not considered possible

6:1

Case by Case

Case by Case

K. Definitions specific to Wetland Mitigation.

1. Restoration. The manipulation of the physical, chemical, or biological characteristics of a site with the goal of returning natural or historic functions to a former or degraded wetland. For the purpose of tracking net gains in wetland acres, restoration is divided into reestablishment and rehabilitation, as follows:

a. Reestablishment. The manipulation of the physical, chemical, or biological characteristics of a site with the goal of returning natural or historic functions to a former wetland. Activities could include removing fill material, plugging ditches, or breaking drain tiles. Reestablishment results in a gain in wetland acres.

b. Rehabilitation. The manipulation of the physical, chemical, or biological characteristics of a site with the goal of repairing natural or historic functions of a degraded wetland. Activities could involve breaching a dike to reconnect wetlands to a floodplain or return tidal influence to a wetland. Rehabilitation results in a gain in wetland function but does not result in a gain in wetland acres.

2. Creation. The manipulation of the physical, chemical, or biological characteristics present to develop a wetland on an upland or deepwater site, where a wetland did not previously exist. Activities typically involve excavation of upland soils to elevations that will produce a wetland hydroperiod, create hydric soils, and support the growth of hydrophytic plant species. Creation results in a gain in wetland acres.

3. Enhancement. The manipulation of the physical, chemical, or biological characteristics of a wetland site to heighten, intensify or improve specific function(s) or to change the growth stage or composition of the vegetation present. Enhancement is undertaken for specified purposes such as water quality improvement, flood water retention or wildlife habitat. Activities typically consist of planting vegetation, controlling non-native or invasive species, modifying site elevations or the proportion of open water to influence hydroperiods, or some combination of these. Enhancement results in a change in some wetland functions and can lead to a decline in other wetland functions, but does not result in a gain in wetland acres.

4. The distinction between rehabilitation and enhancement for the purposes of the rating system is further explained as follows:

a. Rehabilitation includes:

i. Actions that restore the original hydrogeomorphic (HGM) class, or subclass, to a wetland whose current HGM class, or subclass, has been changed as a result of human activities; and

ii. Actions that restore the water regime that was present and maintained the wetland before human activities changed it.

b. Enhancement includes:

i. Any other actions taken in existing wetlands.

ii. For example, a wetland that was once a forested riverine wetland was changed to a depressional, emergent wetland by the construction of a dike and through grazing. Rehabilitating the wetland would involve breaching the dike so the wetland becomes a riverine wetland again, removing the grazing, and reforesting the area. Removing the grazing and reforesting the wetland without reestablishing the links to the riverine system would be considered as enhancement. (Ord. 2083, 2005)

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