When voters approved Prop. Z, a construction bond that will pump $2.8 billion into rehabbing and upgrading San Diego Unified schools, the local charter community had reason to celebrate. After all, they’d been promised a $350 million share of the money.

When it comes to new charters, though, the San Diego Unified school board just moved the goal posts.

Last week, trustees voted 4-1 to up the eligibility requirement for charters seeking Prop. Z dollars. Now, only charter schools that have existed for five years, and have been approved for an additional five years, will be eligible for the funds.

The new policy is the most recent example of the school board’s movement toward increased scrutiny of charter schools. Recently, the board shot down a charter school that met legal requirements, but didn’t convince trustees it would meet its enrollment projections.

In a curious wrinkle, two schools that are shy of the five-year mark — e3 Civic High and Global Vision Academy — will be exempted from the new rule. They’ll be grandfathered in; the other dozen or so charters will have to wait. (School board trustee John Lee Evans said those two schools were unique cases.)

Trustee Scott Barnett, the only board member to vote against the new policy, predicts the decision will “end in a chaotic mess,” and that the school board will eventually be forced to walk it back.

But Evans, who along with Marne Foster proposed the five-year requirement, said it’s the board’s fiduciary responsibility to invest in charters with a proven track record of success.

Here’s a snapshot of how it went down. After voters passed Prop. Z, the school board set up a charter advisory committee to weigh in on how charters’ share of the money will be spent.

Because the charter advisory had been operating under an informal set of guidelines, about a month ago, Barnett and trustee Richard Barrera urged the board to draft and formally adopt policies.

Neither Barnett nor Barrera recommended restrictions, but the district’s charter advisory committee pushed for a one-year requirement. Evans and Foster did them one better, and recommended the five-year policy. And so it came to pass.

Barnett blames himself for pushing for the policy in the first place.

“It’s my own fault,” he said. “This happens. I come up with a good idea and then someone bastardizes it. … So I ended up voting against a policy, 90 percent of which I’d written. It was a good policy before they threw the poison pill in there.”

So what’s the rationale behind the five-year requirement?

Evans said there’s been a rash of failed charters — Iftin University Prep High School and Nubia are two recent examples — that closed for financial or academic reasons. When a charter school closes, it takes money away from another, viable school, he said.

“If they fail financially, who picks up the pieces? Answer: the district, i.e., the taxpayers,” Evans said. “If a charter has been successful academically and financially for five years and is approved another five years there is a higher likelihood of continued operation.”

Barnett, however, questions Evans’ and Foster’s true motivations behind the proposal.

“I know why they really did it, and it’s not what they’d tell you,” Barnett said. “It’s because they’re afraid that once they start handing out money, everybody and their mother is going to come running, trying to jump on the gravy train.”

But, Evans said, any suggestion that the school board is backing off the commitment it’s made to the charter community with Prop. Z is “pure misinformation.”

“Every dollar allocated to charter schools will be spent on charter schools,” Evans said. “No one is being left out.”