BELFAST, Maine — The RSU 20 Board of Directors heard an earful Tuesday night about the financial cliff the nine-town coastal school district faces.

But the directors also heard more about the radical consolidation plan that administrators are suggesting might be one way to address a $2.2 million revenue shortfall. Administrators said they are trying to lessen the estimated school tax assessment increase that has been figured at an average of 11.3 percent in the best-case financial scenario and 15.8 percent in the worst-case scenario.

Those numbers are averaged among the district’s nine communities — Belfast, Belmont, Frankfort, Morrill, Northport, Searsmont, Searsport, Stockton Springs and Swanville.

“Our challenge as an RSU is much more on the revenue side than the cost side,” said Director Gerald Reid of Northport, adding that the board believes the district already has searched to find efficiencies. “Declining enrollment is real and is underpinning our financial challenges.”

Enrollment in the district dropped by 6.3 percent, or 172 students, from 2006 to 2010, and is projected to continue declining by 1-2 percent annually.

John McDonald, the assistant superintendent, said that the proposal to create one high school, one middle school and four elementary schools in the district would save $2.3 million annually and also allow all students to have the same benefits.

The district, combined from the former SAD 56 in Searsport and the former SAD 34 in Belfast, now has two high schools, two middle schools and nine elementary schools.

“Imagine if we planned as if the RSU 20 was a blank canvas,” McDonald said.

The regional high school that would be created would have an enrollment of more than 700 students, he said.

According to this “efficiency model,” all high school students would attend Belfast Area High School. All middle school students would go to a districtwide middle school in the current Searsport District Middle and High School complex. Elementary school pupils would attend either Searsport Elementary School, Captain Albert Stevens Elementary School in Belfast, a regional elementary school to be housed in the former Troy Howard Middle School in Belfast or the Drinkwater School in Northport.

“This model, I assert, is high quality. It is sustainable. It also results in significant cost savings,” McDonald said.

If the directors and the towns want to pursue this model, the earliest the conversion could be completed would be by the 2013-2014 school year, he said.

Other options would save less money but also be less radical, he said.

One would still combine the high schools and middle schools but maintain some of the local elementary schools for an estimated annual savings of $1.5 million.

The other would combine some elementary schools and not combine the high schools or middle schools for an estimated annual savings of $500,000.

McDonald said after the meeting that the concepts “don’t represent hard or fast plans.”

“We’re working hard to explore all the options,” he said.

Some in the room appeared surprised by the magnitude of the estimated average tax increase for schools. Lesley Cosmano, a selectperson for Stockton Springs, said she feels that communication from the RSU 20 central office has not been the best and that the matter is very important.

“I understand the predicament we’re in,” she said. “My biggest concern, of course, is taxes. We have so many people in towns who can’t pay their taxes now.”

According to McDonald, more information about the financial situation for the district will be made available as the budget for the next fiscal year is closer to being drafted. That will happen by the end of March or the beginning of April, he said.