A lunchtime visit to Rosemary Hills Elementary School in Montgomery County — when about 250 kindergartners are let loose for recess — can convey a sense of how crowded the county’s schools have become.

“It can be like ‘Lord of the Flies’ sometimes,” said Rafe Petersen, the parent of a first-grader. “It’s kind of mayhem.”

Rosemary Hills, which serves students from pre-kindergarten to second grade, is built to hold about 475 students, but about 700 students are enrolled this year. At roughly 150 percent capacity, the school is just one of several in the county facing serious overcrowding amid expectations of further growth.

Rising enrollment has created challenges for the school system, including a need for new schools, modernizing sagging buildings and expanding campuses to accommodate students. But county school officials say there isn’t enough money to keep up with the thousands of students expected to pour into the system over the next decade, and they are having to make difficult choices.

“It’s like a triage,” said Bruce Crispell, the director of long-range planning for Montgomery schools. “You take care of the worst space deficits first.”

County officials estimate that more than 10,000 new students will enroll in the public schools in the next six years, a total roughly equivalent to the population of an entire high school each year. Those new students would push enrollment up more than 7 percent, from 148,700 to 159,400 by 2018.

How to pay for more educational space is an unanswered question. With the economy pinching the county’s capital budget, officials recommended delaying or cutting building projects across all departments, including schools.

The fiscal 2014 budget proposal from County Executive Isiah Leggett (D) earlier this year rejected the $14 million the Board of Education requested for capital improvements. It also suggested cutting $20 million in school capital projects between 2015 and 2018.

“It’s not a question of lack of support for the school system, but we have to make our needs fit our resources,” said Patrick Lacefield, a spokesman for Leggett. Lacefield said the county had to prioritize urgent construction projects, such as repairing unsafe bridges or replacing buses that had safety problems.

The County Council restored most of what Leggett recommended cutting but only as a stopgap measure until Montgomery officials tackle the capital improvement budget next year.

The county does a comprehensive update of its six-year capital improvements program in even-numbered years. Board of Education member Patricia O’Neill said a sober picture of how much construction the school system needs will come as the district prepares budget requests to present in 2014.

When Superintendent Joshua P. Starr “unveils his full capital budget in October and we hold hearings in November, it’s going to be breathtaking because it will be the opportunity to really address throughout the county the growth and the aging schools infrastructure,” O’Neill (Bethesda-Chevy Chase) said.

Montgomery population booms in the past mostly happened on the edges of the county, where new development sprung up. But this recent wave of new students is spread throughout the county, from Clarksburg to Bethesda to Wheaton.

“We’re bursting at the seams,” O’Neill said.

Much of the expansion is related to the recent recession, officials said. The bad housing market has kept some families from moving out of Montgomery while simultaneously drawing others to move in with family to save money. More parents have also pulled their kids out of private schools and enrolled them in the public school system.

Cindy Golub’s daughter, Rebecca, transferred to Wootton High School last year. Golub’s youngest son plans to transfer to a Montgomery public school next year.

Both children went from private school to public school to be part of a larger, more diverse student body and have access to more extracurricular activities. But, Golub said, the change does help financially, and “it’s nice to have the option” of choosing between private and public schools.

The county has made progress in addressing space shortages. The district has about 400 portable classrooms on county campuses, down from a peak of almost 700 in 2005. About 90 percent of the portable classrooms are at elementary schools, which means Montgomery soon will have to make more space at middle and high schools.

To accommodate, school officials are considering building larger schools than they have in the past with the money that is available. County Council and Board of Education members also say they’ll focus on lobbying the state for construction funds.

Montgomery educates 17 percent of the state’s population but receives 9 percent of Maryland schools construction funding, council member Phil Andrews (D-Gaithersburg-Rockville) said.

“Montgomery County is continuing to get shortchanged,” Andrews said during an education committee meeting this month. “We need to find a way to persuade our state lawmakers and the governor to allocate and recommend more for [Montgomery County] schools construction relative to what it is getting from the rest of the state.”

Crispell said he expects “relentless enrollment growth” in the system for the next 25 years. That means parents will continue to have students attending overcrowded schools.

“We’re exploding, and it’s frustrating,” Petersen said. “It’s been accepted that our kids will go from trailer to trailer as they progress up through these schools.”