COLUMBIA, Mo. -- Possession of small amounts of marijuana would be decriminalized and medical use of the drug would be legal under two propositions Columbia voters approved by large margins.

Voters there also approved a measure that requires the city to generate or purchase electricity from renewable resources in increasingly higher percentages for the next 18 years.

Nearly 70 percent of voters approved Proposition 1, which allows medical use of marijuana if authorized by a physician, in Tuesday's election. The proposition says that if the prohibition on arrest, prosecution and punishment is deemed invalid, the maximum penalty for such medical use of the drug would be a $50 fine.

A similar proposition makes enforcement of laws against marijuana use the lowest law enforcement priority. It passed with nearly 61 percent approval.

Under the second ordinance, adults cannot be arrested for possessing less than 35 grams of marijuana, but could be charged in municipal court. The measure creates a strong presumption that such marijuana cases would result in deferred prosecution, suspended sentences and community service or drug counseling.

The maximum fine for possessing small amounts of pot would be $250 under the ordinance.

"I am stunned," Columbia prosecutor Rose Wibbenmeyer said Wednesday. "I'm really, really surprised and now I'm looking at it as a matter of, 'Where am I going to put all these files I'm going to have coming into my office?"'

Wibbenmeyer estimated that the number of misdemeanor marijuana charges her department handles will double. Last year, her office prosecuted about 280 misdemeanor pot cases, she said, and sent another 300 to the state for prosecution.

She also wondered how the proposals will impact the state's "Abuse and Lose" laws, which revoke the driver's license of anybody over 21 caught in possession of the drug while driving, and anyone under 21 who is caught in possession of marijuana under any circumstances.

County Prosecutor Kevin Crane agreed that passage of the marijuana measures leaves several unanswered questions -- especially on the medical marijuana issue -- and poses a few problems for law enforcement in a town where most minor marijuana charges already were being referred to municipal court.

"Now that this has passed, does a physician tell a patient to go to a street corner and buy it from a drug dealer, but don't buy crack -- just the marijuana?" Crane said. "Does the act of prescribing illegal medication cause a patient to engage in illegal activity? I think that got lost in the mix."

He said similar proposals failed two years ago, likely because there was an aggressive campaign against them. This time, he said, there was not much vocal opposition.

"I don't think it was a fully informed decision," he said. "A lot of people would have voted yes if they were informed, but a lot of people, if they heard what I was just saying, would vote no."

Crane said supporters argued that college students stand to lose federal aid if they're convicted of marijuana possession. But he said it's not as clear-cut as that.

"The implication is that here's a kid in high school who has a joint and he's going to jail," he said. "It's not happening. The reality of it is they weren't going to jail because we were sending them to the city, anyway."

In the so-called green energy measure, the city must purchase renewable electricity in gradually higher percentages every five years through 2022.

The proposition requires 2 percent of electric retail sales to be from renewable energy sources such as wind, landfill gas and solar power by the end of 2007. That number rises to 10 percent by the end of 2017, and 15 percent by the end of 2022.

That measure passed with slightly over 78 percent of the vote.