SANTA CRUZ — A bill that had been hailed as a much-needed fix to California’s cannabis regulations was vetoed by Gov. Jerry Brown on Sunday, prompting outcry from advocates and promise from the bill’s author to continue pushing for the change.

When recreational pot became legal in California in January, advocates warned the new rules overlooked the neediest medical marijuana users who had relied on donated cannabis from not-for-profit programs.

Since Jan. 1, most of those programs have reportedly shut down, leaving medical marijuana users in limbo.

In August, state lawmakers overwhelmingly approved SB 829, a bill carving out a path to allow cannabis to be donated to medical users tax free.

But Sunday, Brown vetoed the bill, saying it would undermine the the will of voters who passed Proposition 64 in 2016.

“This bill contains provisions that conflict with the strict standards contained in the voter approved Control, Regulate and Tax Adult Use of Marijuana Act,” Brown wrote in a veto statement. “Providing free cannabis to a person with only a doctor’s recommendation undermines these rules and the intent of voters. For this reason, I cannot sign this bill.”

The bill’s author, state Sen. Scott Wiener, D-San Francisco, called the veto a “missed opportunity to help people in desperate need of medicine,” and disputed the governor’s interpretation of Prop. 64 in a statement released Sunday.

“The voters never intended this when they passed Prop. 64, and I remain committed to correcting this oversight,” Wiener said.

Dale Gieringer, who directs cannabis-advocacy nonprofit Cal Norml, called Brown’s veto “outrageous” in an interview with the Sentinel on Monday.

“The notion the notion that the government can tax marijuana that’s given away free of charge for medicine is just absurd,” Gieringer said. “I think the governor has no concept of the impact of this veto.”

A spokesperson for the governor declined to comment further on the veto.

Among the impacted groups is the Santa Cruz-based Wo/Men’s Alliance for Medical Marijuana. Founded in 1993 and often credited as the nation’s oldest pot collective, the not-for-profit group has given away cannabis to thousands of terminally and severely ill members and been labeled the “gold standard” of such programs by a federal judge who in 2004 ordered the Drug Enforcement Agency to leave the group in peace.

Unable to cope with the new regulations, the co-op has been closed since Jan. 1.

“It’s really been super hard for folks,” said Valerie Corral, the organization’s co-founder and director. “They’re poor and they’re without medicine. I do my best personally to take care of people who are the sickest, but they’re having a bad time. A lot of them are back into the black market.”

On Monday evening a steady stream of veterans poured in to the Santa Cruz Veterans Alliance dispensary in Soquel. Inside, the veterans exchanged a voucher for a sealed package containing 8 grams of donated “Kosher Kush.”

The Veterans Alliance is one of the few compassionate care programs in the state that has managed to stay afloat by growing its own cannabis and offsetting its donations with recreational sales.

”This program matters so much to me that I would march on the Federal Reserve Bank,” said Robert Ackerly, 74, a Vietnam veteran who served in the Navy and says he uses cannabis to treat physical pain and post-traumatic stress disorder. “These guys are standing up for veterans, and there’s nothing wrong with pot. It’s a fact that it’s medical.”

Seth Smith, a navy veteran and communications director at the Santa Cruz Veterans Alliance, said he was left disappointed and “a little bit angry” by the governor’s veto.

He estimated SB 829 would have saved the organization about $500 per month in taxes it pays on the pounds of donated pot. But he said the Veterans Alliance will forge ahead with its donation program.

“It’s what we’re built on,” Smith said. “It’s our whole purpose for being — to provide quality cannabis to veterans free of charge.”

Corral, meanwhile, said she remains committed to reopening and is in talks with a landlord at a midtown site. She said the rejection of SB 829 makes that prospect more challenging, but is hoping to make the program solvent by following the Santa Cruz Veterans Alliance model — subsidizing its not-for-profit programs with recreational sales.

“It’s not going to stop us from doing what we need to do for people,” Corral said. “We’ve always done it. We’ve never gotten breaks from the government, but of course we didn’t have to pay taxes on it.”