Can tenants use marijuana in Washington?

[John Hrvatin]

Hey BP, This property is in Washington state where marijuana is legal. I have a tenant who just moved in and upon entering the unit a few days later to hang a shower curtain rod (Shower stall so the curtain is 90 degrees I didn’t feel comfortable with them anchoring it to the wall) I walked into the mud room and was hit with a very strong marijuana smell. The tenants had just signed a drug and smoke free lease upon moving in. Is the tenant able to do this and if not how should I move forward? Thank you in advance!