§ 24.30.075. Wetland mitigation—Types.

Mitigation for lost or diminished wetland and buffer functions shall rely on a type listed below in order of preference. A lower preference form of mitigation shall only be used if the applicant's qualified wetland scientist demonstrates to the approval authority's satisfaction that all higher ranked types of mitigation are not viable, consistent with the criteria in this section.

A.

Restoration. Rectifying the impact by restoring the affected wetland and associated buffer. 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 or its buffer. For the purpose of tracking net gains in wetland acres, restoration is divided into:

1.

Re-establishment. Re-establishing a wetland and buffer on a site formerly occupied by a wetland. 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 or buffer. Re-establishment results in a gain in wetland acres (and functions). Activities could include removing fill material, plugging ditches, or breaking drain tiles.

2.

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. Rehabilitation results in a gain in wetland function but does not result in a gain in wetland acres. Activities could involve breaching a dike to reconnect wetlands to a floodplain or return tidal influence to a wetland.

B.

Establishment (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. Establishment results in a gain in wetland acres. 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.

1.

If a site is not available for wetland restoration to compensate for expected wetland and/or buffer impacts, the approval authority may authorize creation of a wetland and buffer upon demonstration by the applicant's qualified wetland scientist that:

a.

The hydrology and soil conditions at the proposed mitigation site are conducive for sustaining the proposed wetland and that creation of a wetland at the site will not likely cause hydrologic problems elsewhere;

b.

The proposed mitigation site does not contain invasive plants or noxious weeds or that such vegetation will be completely eradicated at the site;

c.

Adjacent land uses and site conditions do not jeopardize the viability of the proposed wetland and buffer (e.g., due to the presence of invasive plants or noxious weeds, stormwater runoff, noise, light, or other impacts); and

d.

The proposed wetland and buffer will eventually be self-sustaining with little or no long-term maintenance.

C.

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. 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. 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 activities. Habitat enhancement is not eligible as a sole method of mitigation. Applicants proposing to enhance wetlands or associated buffers shall demonstrate how the proposed enhancement will increase the wetland's/buffer's water quality functions, how this increase in function will adequately compensate for the impacts, and how all other existing wetland functions at the mitigation site will be protected.

D.

Protection/Maintenance (Preservation) Removing a threat to, or preventing the decline of, wetland conditions by an action in or near a wetland. This includes the purchase of land or easements, repairing water control structures or fences. This term also includes activities commonly associated with the term "preservation." Preservation does not result in a gain of wetland acres. Permanent protection of a Category I or II wetland and associated buffers at risk of degradation, will be used if:

1.

The approval authority determines that the proposed preservation is the best mitigation option;

2.

The proposed preservation site is under threat of undesirable ecological change due to permitted, planned, or likely actions that will not be adequately mitigated under existing regulations;

3.

The area proposed for preservation is of high quality. The following features may be indicative of high quality sites:

a.

Category I or II wetland rating using the wetland rating system for western Washington;

b.

Rare wetland type (for example, bogs, mature forested wetlands, estuarine wetlands);

c.

The presence of habitat for priority or locally important wildlife species (see Chapter 24.25.065 TCC); or

d.

Priority sites in an adopted watershed plan.

4.

Permanent preservation of the wetland and buffer will be provided through a conservation easement or tract held by a land trust, consistent with Chapter 24.65 TCC and TCC 24.30.340—24.30.410.

5.

Ratios for preservation in combination with other forms of mitigation generally range from 10:1 to 20:1, as determined on a case-by-case basis, depending on the quality of the wetlands being impacted and the quality of the wetlands being preserved. Ratios for preservation as the sole means of mitigation generally start at 20:1.

(Ord. No. 14773, § 3(Att. B), 7-24-2012)