Chapter 18.60


Article I. Designation and Rating

18.60.010    Designation and rating of streams.

Article II. Additional Report Requirements – Streams

18.60.020    Critical area report – Additional requirements for streams.

Article III. Performance Standards

18.60.030    Performance standards – General requirements.

Article I. Designation and Rating

18.60.010 Designation and rating of streams.

A. Streams are waterbodies contained within a channel and are either perennial or intermittent. Streams shall be rated according to the criteria in this section.

1. Type 1 water means those streams identified in the Brier shoreline master program.

2. Type 2 water means perennial or intermittent streams that contain salmonid fish habitat.

3. Type 3 water means perennial streams that do not contain salmonid fish habitat.

4. Type 4 water means intermittent streams that do not contain salmonid fish habitat.

B. Mapping. The approximate location and extent of Stream 0056 and Abbey View Drainage is shown on the adopted Stream Classification Map for Stream 0056 and Abbey View Drainage. The map is to be used as a guide for the city, project applicants, and/or property owners, and may be continuously updated as new critical areas are identified. It is a reference and does not provide a final critical area designation. The exact location of a stream’s boundary shall be determined through the performance of a field investigation by a qualified professional. (Ord. 389.A § 1, 2012: Ord. 389 § 1 (Exh. A) (part), 2011)

Article II. Additional Report Requirements – Streams

18.60.020 Critical area report – Additional requirements for streams.

In addition to the general critical area report requirements of BMC 18.10.160, critical area reports for streams must meet the requirements of this section.

A. Stream Analysis. A critical area report for a stream area shall contain an analysis of the stream including the following site- and proposal-related information at a minimum:

1. Location of stream.

2. Stream category.

3. A floodplain study to determine the location of the floodplain in regard to the proposed development.

4. A discussion of measures, including avoidance, minimization and mitigation, proposed to preserve existing stream habitat and restore any stream area that was degraded prior to the current proposed land use activity and to be conducted in accordance with BMC 18.10.190, Mitigation sequencing.

5. A discussion of ongoing management practices that will protect stream habitat after the project site has been developed, including proposed monitoring and maintenance programs. (Ord. 389 § 1 (Exh. A) (part), 2011)

Article III. Performance Standards

18.60.030 Performance standards – General requirements.

A. Activities may only be permitted in a stream or stream buffer if the applicant can show that the proposed activity will not degrade the functions and values of the stream and other critical areas. All unavoidable impacts shall be fully mitigated.

B. Activities and uses shall be prohibited from streams and stream buffers, except as provided for in this title.

C. Buffers.

1. Establishment of Buffers. The following buffers shall be established for streams.

Stream Type

Buffer Widths (Feet)

Type 1

200 feet

Type 2

100 feet

Type 3

55 feet

Type 4

35 feet

2. Measurement of Stream Buffers. All buffers shall be measured from the ordinary high water mark of the stream as surveyed in the field. The width of the stream buffer shall be determined according to the stream category. The buffer for a stream created, restored, or enhanced as compensation for approved stream alterations shall be the same as the buffer required for the category of the created, restored, or enhanced stream.

3. Increased Stream Buffer Widths. The director shall require increased buffer widths in accordance with the recommendations of a qualified professional 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 of the following criteria:

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

b. The buffer area has minimal vegetative cover. In lieu of increasing the buffer width where existing buffer vegetation is inadequate to project the stream functions and values, implementation of a buffer planting plan may substitute. Where a buffer planting plan is proposed, it shall include provisions for monitoring and maintenance to ensure success and preferably include native vegetation, or nonnative, noninvasive vegetation.

4. Reduction of Stream Buffer Widths.

a. The director may allow the standard stream buffer width to be reduced in accordance with an approved critical area report and the best available science on a case-by-case basis when it is determined that a smaller area is adequate to protect the stream functions and values based on site-specific characteristics.

b. This determination shall be supported by documentation showing that a reduced buffer is adequate based on all of the following criteria:

i. The critical area report provides a sound rationale for a reduced buffer based on the best available science;

ii. The existing buffer area is well-vegetated with native species; and

iii. No direct or indirect, short term or long term, adverse impacts to streams will result from the proposed activity including, but not limited to, downstream sedimentation or flooding.

c. The director may require long-term monitoring of the buffer and stream. Subsequent corrective actions may be required if adverse impacts to streams are discovered during the monitoring period.

d. In no case shall the standard buffer width be reduced by more than twenty-five percent, or the buffer width be less than fifty feet, except for buffers for Type 4 streams, which shall not be subject to buffer reduction.

5. Stream Buffer Width Averaging. The director may allow modification of the standard stream 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 demonstrates that:

a. It will not reduce stream functions or values;

b. The stream would benefit from a wider buffer in places and would not be adversely impacted by a narrower buffer in other places;

c. The total area contained in the buffer area after averaging is no less than that which would be contained within the standard buffer; and

d. The buffer width is not reduced to less than fifty percent of the standard width or fifty feet, whichever is greater, except for Type 4 streams, which shall not be subject to buffer width averaging.

D. Fencing of Streams.

1. The director shall condition any permit or authorization issued pursuant to this title to require the applicant to install a permanent fence, as determined by the director, at the edge of the stream buffer, when fencing will prevent future impacts to the stream.

2. The applicant shall be required to install a permanent fence around the stream or buffer when domestic grazing animals are present or may be introduced on site.

3. Fencing installed as part of a proposed activity or as required in this subsection shall be designed so as to not interfere with species migration, including fish runs, and shall be constructed in a manner that minimizes impacts to the stream and associated habitat.

E. Bank Stabilization Measures.

1. New bank stabilization measures shall not be allowed unless no other feasible alternative exists to protect buildings and infrastructure.

2. New, replacement, or substantially improved bank stabilization measures may be permitted in accordance with an approved critical area report that demonstrates the following:

a. Natural stream processes will be maintained;

b. The bank stabilization measures will not degrade fish or wildlife habitat conservation areas or associated wetlands;

c. All unavoidable impacts will be mitigated.

3. Streambank stabilization shall be achieved through bioengineering or soft armoring techniques as described in Washington Department of Fish and Wildlife Publication, “Integrated Streambank Protection Guidelines,” 2002.

F. Roads, Trails, Bridges, and Rights-of-Way.

1. Construction of trails, roadways, and road bridging may be permitted in accordance with an approved critical area report subject to the following standards:

a. There is no other feasible alternative route with less impact on the environment;

b. The crossing minimizes interruption of downstream movement of wood and gravel;

c. Roads across streams or within their buffers shall not run parallel to the water body;

d. Passive trails shall be located on the outer twenty-five percent of the stream buffer, unless prevented by topography or other natural features, and except for limited viewing platforms and crossings;

e. Crossings, where necessary, shall only occur as near to perpendicular with the water body as possible;

f. Mitigation for impacts is provided pursuant to a mitigation plan of an approved critical area report;

g. Road bridges are designed according to the most current versions of the Department of Fish and Wildlife Fish Passage Design at Road Culverts, and the National Marine Fisheries Service Guidelines for Salmonid Passage at Stream Crossings;

h. Roads and bridges shall be designed to not create fish passage blockages and to not cause or block transport of wood, water, and sediment;

i. Trails and associated viewing platforms shall not be made of continuous impervious materials.

G. Utility Facilities.

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

a. Fish and wildlife habitat areas shall be avoided to the maximum extent possible;

b. Installation shall be accomplished by boring beneath the scour depth and hyporheic zone of the water body and channel migration zone, where feasible;

c. The utilities shall cross at an angle greater than sixty degrees to the centerline of the channel in streams or perpendicular to the channel centerline whenever boring under the channel is not feasible;

d. Crossings shall be contained within the footprint of an existing road or utility crossing where possible;

e. The utility route shall avoid paralleling the stream or following a down-valley course near the channel;

f. The utility installation shall not increase or decrease the natural rate of shore migration or channel migration; and

g. Mitigation shall be provided for all unavoidable impacts.

H. 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.

I. Instream Structures.

1. Instream structures and structures within the stream buffer, such as, but not limited to, high flow bypasses, sediment ponds, instream ponds, retention and detention facilities, and dams, shall not be allowed.

2. Instream structures and structures within the stream buffer to improve water quality and fish habitat, excluding those listed in subsection (J)(1) of this section, shall be allowed in accordance with an approved critical area report.

J. Stormwater Conveyance Facilities.

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

a. No other feasible alternatives with less impact exist;

b. Mitigation for impacts is provided and mitigation sequencing is followed; and

c. Vegetation shall be maintained and, if necessary, added adjacent to all open channels and ponds in order to retard erosion, filter out sediments, and shade the water.

K. On-Site Sewage Systems and Wells.

1. New on-site individual sewage systems and wells are not permitted in stream buffers.

2. Repairs to failing on-site sewage systems and wells in stream buffers associated with an existing structure shall be accomplished by utilizing one of the following methods that result in the least impact:

a. Connection to an available public sanitary sewer system or public water system;

b. Replacement with a new on-site sewage system or well located in a portion of the site that has already been disturbed pre-development and is located landward as far as possible, provided the proposed sewage system or well is in compliance with the Snohomish County health department; or

c. Repair to the existing on-site septic system or well. (Ord. 389 § 1 (Exh. A) (part), 2011)