Herndon also said that because there are so many variables that affect overcrowding, it's hard to determine when more portable classrooms are the answer and when building a new school is necessary.

"We're a growing county. We have been for a quite a number of years," Herndon said. "And property is not always available and not easy to come by."

No room to grow

Mike Bowler is a member of the Baltimore County School Board and a Catonsville resident whose grandson previously attended Hillcrest.

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Bowler said the reasons for Hillcrest's troubles stem from its success.

"It's overcrowded because it's an extremely successful school," Bowler said. "In a sense it's a victim of its own success."

That success includes 95-plus percent scores in both the math and reading tests in the annual Maryland School Assessments for the third, fourth and fifth grades at Hillcrest in 2011 and 2012. The score is the highest attainable on the mandatory tests, which are taken every spring. Scores are nearly that high overall for the third-, fourth and fifth-graders at Catonsville and Westchester elementaries as well.

Because the area's schools have such good reputations for test scores and for learning experience, people are moving to Catonsville specifically for the educational opportunities. That creates population surges that are difficult to predict by the county.

"You can count the kids that are coming up (from lower grades), but you can't count the kids who are going to transfer," Bowler said.

In the 17 years that Bowler has lived in Catonsville, he said he's seen an increase from four to 13 children a day at the school bus stop near his house.

"Success is nice," Bowler said. "But it's hard to keep it up when you're bursting at the seams. And there's only so much you can do."

For Hillcrest Principal Terry McVey, the lack of space is the biggest, and fastest growing, problem at the school.

"We're using every possible area that we can locate for storage, for instructing students," McVey said. "We have a lot of areas set up in the hallways."

McVey said that she is asking the county to possibly provide more portable classrooms, which residents know as "trailers," for the 2013-2014 school year.

But she cautioned that would only provide a temporary solution.

"That would get us by next year and maybe the following year, but nothing's definite in terms of staffing, planning or budgets for next year," McVey said.

"Overcrowding has been an issue at Hillcrest for a while," said Erica Mah, who has a daughter in first grade and a son in second grade at Hillcrest. "This is not a new issue."

Mah is one of the parents on a four-person subcommittee looking for answers to the school's overcrowding problem.

Mah said that the school has been dealing with overcrowding for a number of years and, if enrollment keeps growing, the problems could become worse.

Mah said one of the issues as the school becomes more crowded is the building's plumbing system becoming overwhelmed.