Wash. Rev. Code § 70.77.425
It is unlawful for any person to store permanently stocks of fireworks remaining unsold after the lawful period of sale as provided in the person's permit except in such places of permanent storage as the city or county issuing the permit approves. Unsold stocks of consumer fireworks remaining after the authorized retail sales period from nine o'clock a.m. on June 28th to twelve o'clock noon on July 5th shall be returned on or before July 31st of the same year, or remaining after the authorized retail sales period from twelve o'clock noon on December 27th to eleven o'clock p.m. on December 31st shall be returned on or before January 10th of the subsequent year, to the approved permanent storage facilities of a licensed fireworks wholesaler or to a magazine or permanent storage place approved by a local fire official.
RCW 70.77.425
Severability-2002 c 370: See note following RCW 70.77.126.