Activities and uses shall be prohibited from wetlands and wetland buffers, except as provided in this section.
A. Permitted activities; requirements. The following activities may be permitted in a wetland or wetland buffer only if the applicant can demonstrate the activity will not degrade functions and values of the wetland and other critical areas. The Director may require preparation of a critical areas report to confirm compliance with requirements of this title. Mitigation shall be required pursuant to provisions of this title.
1. Enhancement or preservation activities that improve the function of the existing wetland.
2. Modifications to existing structures where no further wetland alteration or increase in structure footprint will occur.
3. Trails. Public and private trails may be allowed within all wetland buffers where it can be demonstrated in a critical areas report that the wetland and wetland buffer functions and values will not be degraded by trail construction or use. Trail planning, construction, and maintenance shall adhere to all of the following criteria:
a. Trail alignment shall follow a path beyond a distance from the wetland edge equal to seventy-five percent (75%) of the buffer width, except as needed to access viewing platforms or view points. Trails may be placed within existing rights-of-way or on existing levees or railroad grades within these limits;
b. Trails and associated viewing platforms shall be constructed of pervious or permeable materials, unless necessary for conformance to the Americans with Disabilities Act. The trail surface shall meet all other requirements, including water quality standards set forth in the Washington State Department of Ecology Stormwater Management Manual for Western Washington, August 2001 or as revised;
c. Trail alignment shall avoid trees in excess of eight inches in diameter at a height of four and a half feet (4.5') above the ground on the upslope side of the tree;
d. Trail construction and maintenance shall follow the U.S. Forest Service Trails Management Handbook (FSH 2309.18, June 1987) and Standard Specifications for Construction of Trails (EM-7720-102, June 1984 or as revised);
Access trails to viewing platforms within the wetland may be provided. Trail access and platforms shall be aligned and constructed to minimize disturbance to valuable functions of the wetland or its buffer and still provide enjoyment of the resource.;
e. Buffer widths shall be increased, where possible, equal to the width of the trail corridor, including disturbed areas; and
f. Equestrian trails shall be located or measures provided to assure that runoff from the trail does not directly discharge to the wetland.
4. Stormwater Management Facilities. Stormwater management facilities are not allowed in Category I and II wetlands and their buffers. Any category of wetland may receive clean runoff from sources such as roof drains and footing drains when such runoff is demonstrated as beneficial to wetland functions. Category III and IV wetland buffers may be used for detention/retention areas where the applicant can demonstrate no practicable alternative and that such use is beneficial to wetland functions. Enhanced treatment is required prior to discharge to such wetlands, and a stormwater facility maintenance plan shall be submitted.
5. Public Roads and Utilities. Footprint expansion of public roads and utilities may occur to maintain locally established levels of service, and to provide for and protect public safety when no lesser impacting option is feasible and the width of the corridor is minimized to the maximum extent practicable. Public and private utility corridors may be allowed within wetland buffers for all categories of wetlands when no lesser impacting alternative alignment is feasible, and wetland and wetland buffer functions and values will not be degraded. Utilities, whenever practicable, shall be constructed in existing, improved roads, drivable surface or shoulder, subject to compliance with road maintenance BMP’s, or within an existing utility corridor. Otherwise, corridor alignment, construction, restoration and maintenance shall adhere to all of the following criteria:
a. Corridor alignment shall follow a path beyond a distance from the wetland edge equal to seventy-five percent (75%) of the buffer width, except when crossing a Category IV wetland and its buffer;
b. Corridor construction and maintenance shall maintain and protect the hydrologic and hydraulic functions of the wetland and the buffer;
c. Corridors shall be fully revegetated with appropriate native vegetation upon completion of construction; and
d. Utilities requiring maintenance roads shall be prohibited in wetland buffers unless the following criteria are met:
(1) There are no lesser impacting alternatives;
(2) Any required maintenance roads shall be no greater than fifteen feet (15') wide.
(3) Roads shall closely approximate the location of the utility to minimize disturbances; and
(4) The maintenance road shall be constructed of pervious materials and designed to maintain and protect the hydrologic functions of the wetland and its buffer. (Ord. 985, 10-5-2020)