BELFAST, Maine — Town managers and elected officials around the eight communities that comprise Regional School Unit 20 were crunching numbers Monday as they figured out what the proposed $34.3 million school budget will mean to taxpayers if approved at the polls next week.

What their calculators told them was not pretty.

Around the district, local property tax assessments for the towns of Belfast, Belmont, Morrill, Northport, Searsmont, Searsport, Stockton Springs and Swanville will increase by 17.2 percent from the last school year, or $3.4 million more.

That number was smaller until last Thursday, when voters who attended an emotional budget meeting voted to reinstate $856,000 worth of slashed funds for art teachers, middle school sports, school secretaries and more.

The school district this year faced budget problems that included decreased state and federal funds, increased costs for insurance and a sharp hike for teacher and support staff salaries. They also lost state subsidies for education when the town of Frankfort voted to withdraw from the district and join SAD 22 to the north.

In Belfast, which is likely to have an 18 percent increase in local taxes for schools, Mayor Walter Ash said that the continued increases are distressing.

“You cannot keep putting the burden back on the taxpayers,” he said. “If the schools keep going the way they’ve been going, they’re going to be unsustainable to the taxpayers. Not just in Belfast, but around the state … I’m just scared, the way it’s headed.”

According to Belfast City Manager Joe Slocum, the proposed school budget would add more than a $300 yearly increase in property taxes for a home valued at $100,000.

“Every dollar is hard on people. It doesn’t matter if you’re a big business or just somebody living in a rented mobile home trying to make ends meet,” he said. “Three hundred dollars just on schools is going to be a real hardship on people. It’s going to hurt everybody.”

In Stockton Springs, a waterfront community with fewer than 2,000 people and just 147 students in the district, spending more for schools would be very hard for residents, said Town Manager Richard Couch.

“What the people of Belfast did last week — it was just unreasonable,” he said. “That meeting was just awful. It was a free-for-all.”

If voters approve the budget, it would cause the estimated mill rate to jump to 16.59 per thousand dollars of valuation from the current rate of 14.25, he said. Also, out of every property tax dollar Stockton Springs residents pay, nearly 75 cents will be earmarked for schools, a 22 percent increase from last year. Couch said that in order to balance the budget, he’s had to freeze municipal salaries, eliminate a groundskeeping position and recreation director and reduce hours at the town hall. He has cut $85,000 from the municipal budget by trimming here and there, he said, and it hurt to see the school district’s voters add so much money to the budget last Thursday night.

“There’s no magic number. If you want to reduce what people pay, you have to reduce your spending,” he said. “It’s not new math. You’ve got to make a reduction. The school didn’t do that.”

In Morrill, a town of fewer than 1,000 people, taxpayers are facing a 20.6 percent increase in assessments for schools. Joyce Scott, the town’s accounts manager, said that in 2008, taxpayers paid $455,000 for schools. If the budget is approved, that sum will rise to $759,000 for the next school year.

“It’s rather preposterous, really,” she said. “It’s an incredible hike. Obviously, people cannot keep going this way. The system is really dysfunctional.”

She said that the district’s residents need clear information, a transparent budget, a very good plan and an educated school board in order to make changes that could positively affect both education and the bottom line.

“I think people could make good decisions if they got good information,” she said.

Brian Thompson, the first selectman from Swanville, said that he doesn’t think that voters will approve this school budget. In his town, the proposed budget would cause the mill rate to go up 1.1 to 17.6. That would mean that taxes on a house valued at $100,000 would go up $110 next year just to pay for the school budget increase.

“People aren’t going to be happy,” he said. “I think people are going to revolt and say, ‘No. Go back and cut it. We can’t take it.’”

Residents will vote on the RSU 20 budget at their municipal polls on Tuesday, June 11.