18.08.184 Streams – Performance standards – General

18.08.184 Streams – Performance standards – General.

A. Establishment of Stream Buffers. The establishment of buffer areas shall be required for all development proposals and activities in or adjacent to streams. The purpose of the buffer shall be to protect the integrity, function, and value of the stream. Buffers shall be protected during construction by placement of a temporary barricade, on-site notice for construction crews of the presence of the stream, and implementation of appropriate erosion and sedimentation controls. Native vegetation removal or disturbance is not allowed in established buffers.

Required buffer widths shall reflect the sensitivity of the stream or the risks associated with development and, in those circumstances permitted by these regulations, the type and intensity of human activity and site design proposed to be conducted on or near the sensitive area. Buffers or setbacks shall be measured as follows.

1. The following buffers are established for streams:

Stream Type	Buffer Width (Feet)
Type 1	200
Type 2	100
Type 3	50
Type 4	25

2. Measurement of Stream Buffers. Stream buffers shall be measured perpendicularly from the ordinary high water mark.

3. Increased Stream Buffer Widths. The director shall require increased buffer widths in accordance with the recommendations of a qualified biologist and the best available science on a case-by-case basis when a larger buffer is necessary to protect stream functions and values based on site-specific characteristics. This determination shall be based on one or more of the following criteria:

a. A larger buffer is needed to protect other critical areas;

b. The buffer or adjacent uplands has a slope greater than 30 percent or is susceptible to erosion and standard erosion-control measures will not prevent adverse impacts to the wetland.

4. Buffer Conditions Shall Be Maintained. Except as otherwise specified or allowed in accordance with this title, stream buffers shall be retained in an undisturbed condition.

5. Degraded Buffers Shall Be Enhanced. Stream buffers vegetated with non-native species or otherwise degraded shall be enhanced with native plants, habitat features or other enhancements.

6. Buffer Uses. The following uses may be permitted within a stream 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 stream:

a. Conservation and Restoration Activities. Conservation or restoration activities aimed at protecting the soil, water, vegetation, or wildlife;

b. Passive Recreation. Passive recreation facilities designed in accordance with an approved critical area report, including:

i. Walkways and trails; provided, that those pathways that are generally parallel to the perimeter of the stream shall be located in the outer 25 percent of the buffer area;

ii. Wildlife viewing structures; and

iii. Fishing access areas;

c. Stormwater Management Facilities. Grass-lined swales and dispersal trenches may be located in the outer 25 percent of the buffer area. All other surface water management facilities are not allowed within the buffer area.

7. Building Setback. A 15-foot building setback is required from the edge of the stream buffer.

C. Stream Crossings. Stream crossings may be allowed and may encroach on the otherwise required stream buffer if:

1. All crossings use bridges or other construction techniques which do not disturb the stream bed or bank, except that bottomless culverts or other appropriate methods demonstrated to provide fisheries protection may be used for Type 2 or Type 3 streams if the applicant demonstrates that such methods and their implementation will pose no harm to the stream or inhibit migration of fish;

2. All crossings are constructed during the summer low flow and are timed to avoid stream disturbance during periods when use is critical to salmonids;

3. Crossings do not occur over salmonid spawning areas unless the city determines that no other possible crossing site exists;

4. Bridge piers or abutments are not placed within the FEMA floodway or the ordinary high water mark;

5. Crossings do not diminish the flood-carrying capacity of the stream;

6. Underground utility crossings are laterally drilled and located at a depth of four feet below the maximum depth of scour for the base flood predicted by a civil engineer licensed by the state of Washington. Temporary bore pits to perform such crossings may be permitted within the stream buffer established in this title; and

7. Crossings are minimized and serve multiple purposes and properties whenever possible.

1. Stream relocations may be allowed only for:

a. All stream types as part of a public project for which a public agency and utility exception is granted pursuant to this title; or

b. Type 3 or 4 streams for the purpose of enhancing resources in the stream if:

i. Appropriate floodplain protection measures are used; and

ii. The location occurs on the site, except that relocation off the site may be allowed if the applicant demonstrates that any on-site relocation is impracticable, the applicant provides all necessary easements and waivers from affected property owners and the off-site location is in the same drainage sub-basin as the original stream.

2. For any relocation allowed by this section, the applicant shall demonstrate, based on information provided by a civil engineer and a qualified biologist, that:

a. The equivalent base flood storage volume and function will be maintained;

b. There will be no adverse impact to local ground water;

c. There will be no increase in velocity;

d. There will be no interbasin transfer of water;

e. There will be no increase in the sediment load;

f. Requirements set out in the mitigation plan are met;

g. The relocation conforms to other applicable laws; and

h. All work will be carried out under the direct supervision of a qualified biologist.

E. Stream Enhancement. Stream enhancement not associated with any other development proposal may be allowed if accomplished according to a plan for its design, implementation, maintenance and monitoring prepared by a civil engineer and a qualified biologist and carried out under the direction of a qualified biologist.

F. Minor Stream Restoration. A minor stream restoration project for fish habitat enhancement may be allowed if:

1. The project results in an increase in stream function and values;

2. The restoration is sponsored by a public agency with a mandate to do such work;

3. The restoration is not associated with mitigation of a specific development proposal;

4. The restoration is limited to removal and enhancement of riparian vegetation, placement of rock weirs, log controls, spawning gravel and other specific salmonid habitat improvements;

5. The restoration only involves the use of hand labor and light equipment; or the use of helicopters and cranes which deliver supplies to the project site; provided, that they have no contact with sensitive areas or their buffers; and

6. The restoration is performed under the direction of a qualified biologist. (Ord. 1036 § 28, 2006).