(1)(a) Agency SEPA policies and procedures shall implement and be consistent with the rules in this chapter. Unless optional or permissive (see WAC 197-11-704), all of the provisions of this chapter are mandatory, and agency procedures shall incorporate these rules and criteria.

(b) Permissive and optional rules shall not be construed as mandatory requirements. Rules giving encouragement or guidance shall also not be construed as mandatory. The decision on whether to apply an optional provision rests with the responsible official.

(c) Except as stated in the next subsection, the rules in this chapter are not exclusive, and agencies may add procedures and criteria. However, any additional material shall not be inconsistent with, contradict, or make compliance with any provision of these rules a practical impossibility. Any additional material shall be consistent with SEPA.

(d) Agency procedures shall also include the procedures required by sections WAC 197-11-055 (3)(a) and (4), 197-11-420 (1) and (4), and 197-11-910.

(e) Agency procedures may include procedures under WAC 197-11-055 (2) and (7), 197-11-100(3), 197-11-680, 197-11-714(2), 197-11-800(1), and 197-11-908. Any such procedures shall include the content required by those rules.

(2) The following provisions of this chapter are exclusive and may not be added to or changed in agency procedures:

(a) The definitions of "proposal," "major," "action," "significant," "affecting," "environment," "categorical exemption," "agencies with jurisdiction," "lands covered by water," "built environment," "natural environment," "license," "licensing," "mitigation," and "scope";

(b) The criteria for lead agency determination (Part Ten of these rules);

(c) The categorical exemptions in Part Nine of these rules, unless expressly allowed under Part Nine;

(d) The information allowed to be required of applicants under WAC 197-11-080, 197-11-100, 197-11-335, and 197-11-420;

(e) The requirements for the style and size of an EIS (WAC 197-11-425);

(f) The list of elements of the environment (WAC 197-11-444); and

(g) The provisions on substantive authority and mitigation in WAC 197-11-660.

(3) The following provisions of this chapter may not be changed, but may be added to; any additions shall meet the criteria for additional material stated in subsection (1)(c) of this section:

(a) All other definitions in Part Eight of these rules;

(b) The provisions in Parts Four and Five of these rules, except as necessary to be grammatically incorporated into agency procedures;

(c) The contents of agency SEPA procedures (WAC 197-11-906); and

(d) The list of agencies with environmental expertise (WAC 197-11-920).

(4) The forms in Part Eleven shall be used substantially as set forth. Minor changes are allowed to make the forms more useful to agencies, applicants, and the public, as long as the changes do not eliminate requested information or impose burdens on applicants.