PIERRE, S.D. (AP) — Members of the Oglala Sioux Tribe passed a referendum to legalize medical and recreational marijuana on the Pine Ridge Reservation in South Dakota, according to preliminary results from the tribe’s election commission.

A proposal to allow alcohol in the tribe’s casino failed.

The results of Tuesday’s vote will be certified by the end of the month. In the tally from all precincts announced on Wednesday morning, both medical and recreational marijuana passed by wide margins, with 82% of voters approving medical marijuana and 74% approving recreational pot. The alcohol proposal failed by 12 percentage points.

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The Oglala Sioux will become the only Native American tribe to set up a cannabis market in a state where it’s otherwise illegal. The tribal council is next supposed to enact laws for how marijuana will be legalized and regulated. According to initial plans, the tribe will not take ownership of cannabis production or retail, but license individuals and put a retail tax on pot. The Tribal Council will take up the issue on March 31.

Chase Iron Eyes, a spokesperson for the tribe’s president, Julian Bear Runner, said the vote reflected the difference in how many tribal members perceive alcohol and marijuana. He called alcohol a “poison” that was forced on the tribe; whereas he described marijuana as a “healing plant” that presented a path out of poverty and historical trauma.

Iron Eyes said that though traditional Lakota society still eschews both alcohol and pot, people were swayed by the medicinal and economic potential in cannabis.

Tribal leaders have pitched setting up a marijuana resort near the tribe’s casino in order to attract tourists visiting the Black Hills. They envision a small eco-tourism industry developing from the increase in visitors.

Rick Gray Grass, who is part of the tribe’s executive leadership and pushed the marijuana proposal, said he hopes to have dispensaries open by August or September. He is still formulating the regulations that will be presented to the tribal council. He expected the council to limit people to purchasing an ounce of pot and enact security measures to prevent people from taking it off tribal land.

Still, the proposal sets up a potential conflict with federal and state authorities. The Flandreau Santee Sioux Tribe in the eastern part of the state attempted to grow and sell marijuana in 2015, but ended up burning its cannabis plants after conflicts with federal and state governments.

Gray Grass argued that the tribe’s treaty with the federal government allows them to act as a sovereign nation. “I think we have a stronger stand on Pine Ridge,” he said.

Tribal leaders said they want to cooperate with authorities in setting up a marijuana market and have discussed their plans with the U.S. attorney’s office for the state. Federal and state law enforcement has not commented on the issue.

The tribe is also looking for ways to get people prescriptions for medical marijuana. Indian Health Services, which provides most of the healthcare on the reservation, will not prescribe marijuana because it is a federal agency. The tribe’s current plans do not have special provisions for people with prescriptions.

South Dakota voters will also decide on medical and recreational marijuana legalization in a referendum on ballots in November.

If voters decide to legalize marijuana in the state, it could mean a boom for the tribe’s marijuana market. They would have a head start in growing and selling pot, making tribal members the only retailers in the state for a period.

Trent Hancock, a marijuana producer from Oregon who has helped the tribe formulate its pot plans, hoped that tribal members could sell $100 million of the product in a year under that scenario.