Ord 2625 - TMC Title 18 Chapters - Critical Areas Regulations

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10. Protect the critical area from human and domestic animal disturbance. An undisturbed and high quality critical area or buffer may substitute for the yard setback and landscape requirements of TMC Chapter 18.50 and 18.52. C. WATERCOURSE BUFFER WIDTHS. The following buffer widths, measured from the Ordinary High Water Mark (OHWM), apply to each side of a watercourse. If the OHWM cannot be determined, then the buffer will be measured from the top of bank: Overlay. 1. Type S Watercourse: Regulated under TMC Chapter 18.44, Shoreline 2. Type F Watercourse: 100-foot-wide buffer. 3. Type Np Watercourse: Standard 80-foot-wide buffer; alternate buffer in the 50-65 range allowed with buffer enhancement. 4. Type Ns Watercourse: 50-foot-wide buffer. D. BUFFER SETBACKS. 1. All commercial and industrial buildings shall be set back 15 feet and all other development shall be set back 10 feet. Building setbacks shall be measured from the foundation to the buffer's edge. Building plans shall also identify a 20-foot area beyond the buffer setback within which the impacts of development will be reviewed. 2. The Director may waive setback requirements when a site plan demonstrates there will be no impacts to the buffer from construction or occasional maintenance activities. E. VARIATION OF STANDARD WATERCOURSE BUFFER WIDTH. 1. Buffer averaging may be allowed by the Director as a Type 2 decision if the total area of the buffer after averaging is equal to the area required without averaging and the buffer at its narrowest point is never less than either 3/4 of the required width; and the following criteria is met: a. The watercourse has significant differences in characteristics that affect its habitat functions, and the buffer is increased adjacent to the higher -functioning area of habitat or more -sensitive portion of the watercourse and decreased adjacent to the lower - functioning or less -sensitive portion as demonstrated by a critical areas report from a qualified professional. b. There are no feasible alternatives to the site design that could be accomplished without buffer averaging, and the averaged buffer will not result in degradation of the watercourse's functions and values as demonstrated by a critical areas report. c. Compliance with mitigation sequencing requirements (TMC Section 18.45.075). d. Compliance with TMC Chapter 18.45.158, "Vegetation Protection and Management." w:\Legislative Development\Critical Areas update 2-25-20 MD:bjs Review and analysis by Barbara Saxton Page 29 of 87