Not easy to track the process through the RCW and the WAC. Found the following 2 sections in WAC 220 - Fishing that appear to be applicable and tie back to RCW references giving the Commission/Director the authority to set licensing requirements.
220-55-015
Valid recreational license required.
It is unlawful for any person required to have a recreational license to take or possess fish, shellfish, seaweed, or wildlife for personal use without having in physical possession a valid license or a valid internet or telephone authorization number.
[Statutory Authority: RCW 77.32.050. WSR 00-11-178 (Order 00-80), § 220-55-015, filed 5/24/00, effective 6/24/00. Statutory Authority: 1998 c 191 and RCW 75.08.080. WSR 99-03-029 (Order 99-02), § 220-55-015, filed 1/13/99, effective 2/13/99. Statutory Authority: RCW 75.08.080. WSR 94-23-059 (Order 94-162), § 220-55-015, filed 11/14/94, effective 12/15/94; WSR 94-01-001, § 220-55-015, filed 12/1/93, effective 1/1/94; WSR 89-07-071 (Order 89-05), § 220-55-015, filed 3/20/89; WSR 79-09-021 (Order 79-58), § 220-55-015, filed 8/10/79.]
220-55-160
Free fishing weekend.
The Saturday and Sunday following the first Monday in June is declared to be free fishing weekend in Washington. On this weekend a fishing license is not required for any person, regardless of age or residency, to fish for or possess fish and shellfish and a fish and wildlife lands vehicle use permit is not required to utilize department parking facilities except that it is unlawful to fish for or possess any species for which a catch record is required without a valid catch record card in possession. Anglers may fish with two poles in all lakes where it is legal to do so without purchasing a two-pole endorsement, and may also fish in all open areas of the Columbia River and tributaries without purchasing a Columbia River endorsement. During free fishing weekend only the license, endorsements, and permit provided for in this section are affected, and all other rules including the catch record card requirement remain in effect.
[Statutory Authority: RCW 77.04.020 and 77.12.047. WSR 11-16-103 (Order 11-184), § 220-55-160, filed 8/3/11, effective 9/3/11. Statutory Authority: RCW 77.12.047. WSR 06-13-023 (Order 06-135), § 220-55-160, filed 6/13/06, effective 7/14/06. Statutory Authority: RCW 75.08.080 and 77.12.040. WSR 99-08-029 (Order 99-13), § 220-55-160, filed 3/30/99, effective 5/1/99.]
All of the fishing regulations can be found in this link to WAC 220
http://apps.leg.wa.gov/wac/default.aspx?cite=220