17.130.060 Standard buffer width requirements.
Buffers shall be required for all streams regulated by this chapter. Required stream buffer widths are as stated in this section.
(1) Required widths for stream buffers are as follows:
(a) For Type S streams – 150 feet;
(b) For Type F streams – 100 feet;
(c) For Type Np streams – 75 feet; and
(d) For Type Ns streams – 50 feet.
(2) Measurement. The buffer shall be measured horizontally in a landward direction from the ordinary high water mark. Where lands adjacent to a stream display a continuous slope of 25 percent or greater, the buffer shall include all such sloping areas. Where the horizontal distance of the sloping area is greater than the required standard buffer, the buffer shall be extended to a point 25 feet beyond the top of the bank of the sloping area.
(3) Averaging Buffer Widths. The width of a buffer may be averaged, thereby reducing the width of a portion of the buffer and increasing the width of another portion, if all of the following requirements are met:
(a) Averaging will not impair or reduce the habitat, water quality purification and enhancement, stormwater detention, groundwater recharge, shoreline protection and erosion protection, and other functions of the stream or buffer;
(b) The total area of the buffer on the subject property is not less than the buffer which would be required if averaging were not allowed; and
(c) No part of the width of the buffer is less than 65 percent of the required width or 25 feet, whichever is greater.
(4) Buffer Width Reduction. Buffer widths may be reduced if the buffer is enhanced in accordance with the following requirements:
(a) Buffer width reduction and enhancement is targeted for buffer areas that have minimal functional values due to existing physical characteristics;
(b) The applicant demonstrates that proposed buffer enhancement, together with proposed buffer width reduction, will result in an increase in the functional value of the buffer when compared with the functional value of the standard buffer;
(c) The applicant includes a comparative analysis of buffer values prior to and after enhancement, and demonstrates compliance with this section, as part of the critical area report required by SMC 17.130.090;
(d) The buffer width is not reduced below 75 percent of the standard buffer width, or 25 feet, whichever is greater, and the total buffer area reduction is not less than 75 percent of the total buffer area before reduction; and
(e) The functional values of the stream protected by the buffer are not decreased. (Ord. 1475 § 3 (Att. C), 2019; Ord. 1164 § 4, 2004).