The Olympian reports that board spokesman Mikhail Carpenter says the rule change likely goes into effect 30 days after Wednesday's unanimous board vote.
By mid-January, the ban could affect marijuana smokers on the second floor of Frankie's Sports Bar in Olympia.
Frankie's has been allowing bar patrons to smoke marijuana in an upstairs private room for about a year. Bar owner Frank Schnarr has contended that members could smoke legally there after the passage of Initiative 502, which made it legal for adults 21 and older to possess up to an ounce of marijuana in Washington.
The newspaper says while other Washington bars currently prohibit smoking, Schnarr won a prior legal battle to allow patrons to smoke cigarettes in an upstairs room, provided that they pay $10 in annual dues.
Schnarr has spoken out against the rule change and says he'll ignore it.