The bill, introduced by Democratic Rep. Christopher Hurst of Enumclaw and Republican Rep. Terry Nealey of Dayton, says that if less than an ounce of pot is found at a store with a pharmacy, the store must notify law enforcement, and the marijuana must be properly disposed of.
Supporters say the bill was prompted by recent incidents where marijuana was found at Walmart stores, after it was apparently dropped. There was concern that having marijuana on the premises could affect the licensing of the pharmacies at such stores.
Washington voters legalized possession of up to an ounce of marijuana last fall.
The bill now, passed by the House Friday night, heads to the Senate for consideration.