Cal. Pub. Res. Code § 4590

(a)
1. (1) A timber harvesting plan approved by the department on or after July 1, 2012, is effective for a period of not more than five years, unless extended pursuant to paragraph (2).
2. (2) A timber harvesting plan, pursuant to which timber operations have commenced, but have not been completed, may be extended by amendment for two years in order to complete the timber operations, if both of the following conditions are met:
  1. (A) Good cause is shown.
  2. (B) All timber operations are in conformance with the timber harvesting plan, this chapter, and all applicable rules and regulations, upon the filing of the notice of extension as required by this section.
(b) The extension shall apply to any area covered by the timber harvesting plan for which a report has not been submitted under Section 4585. The notice of extension shall be provided to the department not sooner than 140 days, but at least 10 days, prior to the expiration date of the timber harvesting plan. The notice shall include the circumstances that prevented a timely completion of the timber operations under the timber harvesting plan and, consistent with Section 4583, an agreement to comply with this chapter and the rules and regulations of the board as these exist on the date the extension notice is filed.
(c) Stocking work may continue for more than the effective period of a timber harvesting plan under subdivision (a), but shall be completed within five years after the conclusion of other work.
(d) In addition to the extension authorized by paragraph (2) of subdivision (a), a timber harvesting plan that is approved by the department from January 1, 2014, to December 31, 2015, inclusive, may be extended by amendment for an additional two years in order to complete the timber operations, if the timber harvesting plan complies with subparagraphs (A) and (B) of paragraph (2) of subdivision (a) and the notice of extension, pursuant to subdivision (b), includes written certification by a registered professional forester that neither of the conditions in subdivision (e) has occurred.
(e) The department shall not approve an extension of a timber harvesting plan pursuant to subdivision (a) or (d) if either of the following has occurred:
1. (1) Listed species, as defined in Article 1 (commencing with Section 2050) of Chapter 1.5 of Division 3 of the Fish and Game Code or the federal Endangered Species Act (16 U.S.C. Sec. 1531 et seq.), have been discovered in the logging area of the timber harvesting plan since approval of the plan.
2. (2) Significant physical changes to the harvest area or adjacent areas have occurred since the timber harvesting plan’s cumulative impacts were originally assessed.
(f) An extension of a timber harvesting plan for which either of the conditions in subdivision (e) has occurred may be obtained only pursuant to Section 1039 of Title 14 of the California Code of Regulations.