Abbotsford, Stratford and Tomorrow Rivers districts in the Marshfield area have grown between 15 and 20 percent in recent years, News-Herald Media reported Monday.
Most Wisconsin school districts have been posting enrollment declines.
Increasing enrollment has meant more funding but also greater costs. School leaders are concerned state revenue limits will eventually leave them unable to cover expenses, and they're scrambling to fit students into existing classrooms to avoid costly construction.
"We're basically full again now after adding eight classrooms," Stratford district administrator Scott Winch said. "Space is a big issue within the district."
School leaders in the growing districts credit the area's Hispanic population, which has been increasing since 2000. The Hispanic population in Abbotsford grew 555 percent between 2000 and 2010.
"We're going to propose adding an extra math teacher next year just because our sections are getting so big," Winch said. "We'll be taking away one of our distance learning rooms to do that, and we'll need to find a place to put (that equipment)."
Researchers with the University of Wisconsin Applied Population Laboratory say while 59 percent of Wisconsin's rural districts posted enrollment declines between 2008 and 2013, the trend isn't likely to change.
Some districts are shifting the courses they can offer in order to meet the shifting demographics, while moves some districts made years ago are proving useful.
"I think we had a jump-start on developing programs (15 to 20 years ago) to serve those students in our (English as a second language) program," said Reed Welsh, district administrator for Abbotsford.
The schools are levying the most they are allowed by state law in order to ensure sure they can avoid budget shortfalls in the future.