PORTLAND — Maine planning officials said they were not surprised by preliminary figures published by the U.S. Census Bureau this week showing that the state’s population grew by 8.3 percent during the past decade.

According to figures from the 1990 census, there are now more than 1.2 million residents in Maine.

Lincoln and York counties grew the most — by about 17 percent each — while Aroostook County showed an 8 percent decline.

“The young people are leaving. We’ve seen school enrollments decline with each graduating class. There are better jobs elsewhere,” said Caribou City Manager Terry P. St. Peter.

Cumberland County, the most heavily populated county, grew by 12 percent to 241,865, according to the census figures.

The state has not determined which communities experienced the most growth in the 1980s.

The Census Bureau said the population figures are incomplete because some tabulations have not been computed. States and municipalities have two weeks to challenge any figures that appear to be incorrect.

Senior planner Henry C. Nichols of the Office of Comprehensive Planning said the overall modest rise in the state population figures reflects a trend of steady growth that has been going on for years.

He also said the population decline in Aroostook County parallels a trend that has appeared in virtually every part of the country as people move from rural areas to urban centers where there are better chances for employment.

Cities and towns are concerned about census figures because the amount of funding that municipalities receive from state and federal sources depends on population.

South Portland, for example, shows a 2 percent increase in population since 1980, and the city hopes that growth will make it eligible for special community block grants targeted for urban centers.

Towns and cities now have 15 working days to dispute the figures for residents, households, vacant homes and group quarters such as nursing homes.

Ellsworth’s population is pegged at 5,980, about 20 percent higher than in 1980, but City Manager Herbert Gilsdorf disagrees with the figure.

“We feel we’ve been grossly undercounted,” he said. “Our own estimate is at least 1,000 people higher,” largely because of “a tremendous number of camps here that are hard to find.”