Challis, Stanley and Clayton all registered population increases in the decade from 2000 to 2019, but Mackay lost residents, according to a report from Census Bureau and the Idaho Department of Labor.

Challis had an estimated 1,091 residents in 2019, a 0.9 percent of an increase from the 1,081 residents in 2010, the report shows. The 2018 count was 1,079.

Stanley had a hefty 9.5 percent increase in residents, growing to 69 in 2019, up from 63 in 2010.

Mackay’s population declined from 517 in 2010 to 501 in 2019, a 3.1 percent drop, the report shows.

Tiny Clayton had a big percentage change — 14.3 percent, but that was just one person. Clayton’s official 2019 population was 8, up from 7 in 2010.

Salmon recorded a 1.8 percent population increase, ending up with 3,169 residents in 2019, compared to 3,112 in 2010.

Arco saw a big decrease in population in the decade, dropping 11.6 percent to 880 residents, from 995 in 2010.

The city of Moore also saw a large loss in residents, declining 10.1 percent to 170 residents in 2019, from 189 in 2010.

The population study shows that cities in Idaho have been thriving in recent years, while many small towns in rural areas are not seeing the same level of growth.

Challis Mayor Mike Barrett said a growth rate of 1 or 2 percent a decade is probably what can be expected. At that rate, there’s no big looming concern about the city’s infrastructure being adequate to handle the additional residents, he said. But, he pointed out, the city is experiencing problems with two water wells, and one of those wells may not be reparable.

“We need a 16-inch commercial well now,” Barrett said. The slow-sand filter the city uses “isn’t great in the winter,” making a larger well important.

“So if we had a big surge in population, we could have a problem,” he said. If that did happen, the city could follow the procedures it used in the 1980s when additional money was collected upfront as development occurred to pay for needed new infrastructure.

The city’s sewer system was designed to handle about 1,300 residents, Barrett said because of the large growth that occurred in the 1980s. The population of Challis grew by 500 or so people to 1,285 when Cyprus Minerals was at its peak, Barrett said. So, the city built an adequate sewer system for that population level. Lagoons need to function at or near capacity to stay healthy, he said.

Barrett believes Challis is being discovered by people who have multiple homes and live in the community only part of the year. Along with empty-nesters who move here, he expects a growth rate of 1 to 2 percent to continue for the foreseeable future.

The Census Bureau reports that eight Idaho cities now have more than 50,000 residents, with Twin Falls exceeding the threshold to be classified a metropolitan statistical area. Twin Falls has an estimated 50,197 residents. The other cities with populations above 50,000 are Boise at 228,959, Meridian at 114,161, Nampa at 99,277, Idaho Falls at 62,888, Caldwell at 58,481, Pocatello at 56,637 and Coeur d’Alene at 52,414.