A new law will drastically change the way some towns share the cost of school districts.

And now many school officials worry that rich towns with few students will get a break at the expense of poor towns with many students.

Currently, most SADs divide the cost of schools among their towns, basing each contribution on the property value of each town. Rich towns put more money into the school system. Poor towns contribute less. It doesn’t matter how many students each town sends to school.

A state law approved during the last legislative session changes that, forcing most SADs and CSDs to combine both valuation and student enrollment when calculating each town’s share. The new law is set to take effect July 1.

Some school districts say the new method will topple the delicate balance among towns that share a school system.

“We really, really get killed,” said SAD 43 Superintendent James Hodgkins, who oversees schools in Byron, Mexico, Roxbury and Rumford.

But while state officials acknowledge that some SADs will see a major shift, they say most school administrators are worried for no reason.

“The vast majority won’t be affected,” said Jim Rier, a finance specialist for the Maine Department of Education,

SAD 44 Superintendent David Murphy, who oversees schools in Andover, Bethel, Greenwood, Newry and Woodstock, learned of the change just before the law passed last year.

Buried in a school funding bill, the clause altered the way most SADs figure each town’s share. Murphy said he quickly realized that one town’s share would drop dramatically – and the contributions from the others would rise – when he factored in enrollment. Newry, a small ski town with high property values but few students, would see its school contributions drop about $930,000, Murphy said. The other four towns would have to pay between $130,000 and $500,000 more.

“In reality, that’s probably not something they can do,” Murphy said.

Murphy said he discussed the situation with legislators in the region, but the bill passed with little attention. He brought it up with town officials this winter.

“Somebody’s got to ride in here on a white horse and save us,” he said.

Soon other school districts began paying attention.

SAD 72 Superintendent George Cunningham said he already considers both a town’s valuation and its number of students when calculating shares of the SAD. But with the new formula, he believes Fryeburg’s contribution will still decrease by 5 percent. Denmark’s share will increase by 6 percent.

That may not sound like much, he said, but 5 percent equals $460,000.

“What concerns me is this is going to exacerbate differences and create some disunity in the ranks,” he said.

The state believes the shift won’t be so dramatic in SAD 72. But by Tuesday afternoon, the Maine Department of Education didn’t have specifics.

Hodgkins, superintendent in SAD 43, said he is still trying to calculate how the change will affect his four western Maine towns. Although he hadn’t received specific figures from the state, he said, his own preliminary calculations make him believe Byron, Roxbury and Rumford will see their contributions go down. Mexico, a poor town with a large number of students, will see its share rise.

He believes the small town can’t afford to pay any more.

“It will be absolutely devastating to the town of Mexico,” he said.

The Maine Department of Education has tried to allay fears about the change. State officials maintain that most districts won’t see much of a difference with the new formula. Those who do are anomalies, Rier said.

“There are a very small number that are in that situation,” he said.

The Maine Department of Education plans to release today a detailed list of every SAD and CSD in Maine and how the change will affect them.

Earlier this week, the department told the Legislature’s Property Tax Reform Committee that most school districts won’t see much of a difference. The committee recommended that those greatly impacted, including SAD 43, SAD 44 and SAD 72, be allowed to phase in the change during a four-year period. The full Legislature must still approve the recommendation.

Some SAD officials say a phase-in may help. But they aren’t celebrating yet.

“That’s certainly a step in the right direction,” Murphy said. “I’ll have to look at it to let it sink in.”