AUGUSTA — City officials have doubts about the accuracy of U.S. Census population estimates that indicate Augusta’s population decreased by more than any other city in Maine from 2010 to 2015.

Recent U.S. Census Bureau estimates show the city’s population decreased from 19,136 at the time of the 2010 Census to 18,471 in 2015, according to population estimates done every year. That would be a decrease of 665 people, or just under 3.5 percent.

Mayor David Rollins and city administrators said the methodology used in non-Census count years to estimate populations isn’t accurate at estimating population changes in small municipalities such as Augusta and those in most of Maine. They said the methodology relies heavily on housing data, such as building permits and the number of housing units.

Augusta has lost a significant amount of rental housing units over the last several years to fires and because buildings were closed after they were deemed unsafe for habitation. But that doesn’t mean all the people living in those units left Augusta, just that they left that specific unit, city officials said.

“We have lost a number of units in Augusta to fire or buildings being closed because they weren’t safe for habitation, but I’m not convinced those people left Augusta,” said Matt Nazar, development director for the city. “It may be accurate that the city has lost some population. But until we see the 2020 Census data, I’m not yet convinced” Augusta lost as many people as the data suggests.

Nazar also noted the population estimates tend to be less accurate for small municipalities than for larger population bases, such as counties and entire states. Nazar said when he worked for the State Planning Office, a Census worker agreed the municipal estimates were often inaccurate because the methodology used doesn’t work well for small populations.

“For states the size of Maine, at the municipal level, the estimates are problematic,” he said. “Not necessarily completely inaccurate but problematic. The smaller the numbers are, the more amplified the discrepancies look.”

Rollins, a real estate appraiser by profession, said he hasn’t seen any indications Augusta saw a population decline of 3.5 percent over the last several years. He said he sees no corresponding drop in real estate values or sale prices that he would expect if significant numbers of people were leaving the city.

“I can’t see that we’ve had a 3.5 percent drop in population,” he said. “That’s only a projection, and those numbers, according to our planning department, are not typically accurate at the municipal level. Those numbers don’t usually come to fruition. If we really lost that many people, you’d see a downturn in (property) values. And the real estate numbers aren’t showing that.”

The median sales price of a single-family home in Kennebec County increased from $132,700 in 2010 to $139,000 in 2015, according to Maine Association of Realtors data, which was not broken down by municipality.

The Maine city losing the second-most population from 2010 to 2015, according to the Census estimates, was Bangor, which lost 648 residents.

Some smaller Maine cities lost a bigger percentage of their population than Augusta, according to the estimates, including the northern Maine cities of Caribou and Presque Isle. Caribou lost 373 residents, which is 4.5 percent of its population, while Presque Isle lost 521 people, 5.4 percent of its population.

Other local cities also saw their populations decrease, according to the estimates. Gardiner’s population went from 5,800 in 2010 to 5,597 in 2015, a 3.5 percent decrease amounting to 203 persons.

Hallowell, during that same period, went from 2,381 to 2,315, a 2.8 percent decrease.

Waterville appears to have bucked that trend, increasing its population from 15,722 in 2010 to 16,261 in 2015, a 3.4 percent increase amounting to 539 persons.

The Census estimates indicate Maine’s population is relatively unchanged overall at 1,329,328 in 2015, 967 more people than it had at the time of the 2010 Census.