WASHINGTON — City officials didn't think they were taking a big risk about a year ago when they decided to pay the U.S. Census Bureau to conduct a partial special census in neighborhoods that had grown substantially since the 2010 decennial U.S. census.

Besides their optimism that the growth had substantially increased the city's population, the officials had some facts in their pocket.

"We knew how many building permits had been granted the last seven, eight years in those neighborhoods and the average household size of the owner-occupied and rental units there," said Jon Oliphant, Washington's planning and development director.

"But I still thought it was prudent to aim low with my estimate of what the special census would show," he said.

Oliphant estimated 1,013 new residents would be counted in the special census, conducted mainly in neighborhoods that were not affected by the 2013 tornado.

The actual special census number, announced last week by the city, was 1,432. So Washington's population is now 16,566, a nearly 9.5 percent increase from the 2010 population of 15,134.

"Was I surprised by the special census result? To be honest, no," Oliphant said. "It pretty much confirmed what I thought."

The new population means the city will receive an estimated $600,000 in additional population-based funding from the state between June 2018 and June 2021, when the results of the 2020 U.S. census will be certified.

That's about $200,000 more than city officials' guess of $400,000.

Municipalities receive revenue from the state on a per capita basis from income, use and motor vehicle taxes.

Subtract the estimated $113,570 that Washington will pay the Census Bureau for the special census, and the city's net gain from the special census will be about $486,430.

Washington Mayor Gary Manier said the additional state funds will be used mainly for infrastructure work.

"We fell behind on that work because of the tornado and we need to catch up," he said. "We spent about 2 1/2 years after the tornado fixing the damages."

Eight Washington residents were hired as temporary workers by the Census Bureau to help with the special census, which was conducted late last year in parts of the Oak Creek, Bristol Park, Northwyck, Hunter's Glen, Cherry Pointe, Mallard Crossing, Trail's Edge, Washington Estates, Devonshire, Wilmor Estates and Villas of Hollybrook neighborhoods.

Mainly because of the workers' efficiency, Oliphant said, the city saved money on its rental of a 1,900-square-foot office in the Cherry Tree Shopping Center and the time it took to do the special census.

The Census Bureau requires a municipality having a special census done to supply temporary office space that meets Census Bureau requirements.

"We rented the office (for $800 per month plus utilities) for a minimum of three months starting in mid-October and we were out in about 60 days," Oliphant said. "We got great feedback from the Census Bureau about how the special census was conducted. That says a lot about our city staff, elected officials, census workers and the residents who were counted."

The Census Bureau originally estimated a nine- to 10-month timeline to complete and certify the special census.

Manier floated the idea of a special census to Oliphant a few months before the City Council's approval May 1, 2017.

"I thought it was time to do a special census," Manier said. "I know what kind of city we had before the tornado and what kind of city we have now. It's a place where people want to move. I've had people tell me they moved to Washington because of how we responded to the tornado."

Steve Stein can be reached at 686-3114 or stevestein21@yahoo.com. Follow him on Twitter @SpartanSteve.