Mariana Taylor, a mother of two young children, has attended school meetings and has spoken to neighbours and parents rallying to their common cause. She has posted a sign on the front lawn of her Mississauga home: "S.O.S. SAVE OUR SCHOOL."

But her school is not being closed.

Instead, Ms. Taylor is facing down the possibility that Mineola Public School could be converted into a French-immersion-only school, meaning her children – students in the regular English stream – would have to go elsewhere and would no longer be able to walk to their neighbourhood school.

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"I think it's alarmed a lot of parents, because we have all this uncertainty of what the future holds," she said.

Her worries are felt by other families in many parts of the country.

French immersion is popular – enrolment climbed about 41 per cent between 2004-05 and 2014-15, according to Statistics Canada. It is also a continuing challenge for school boards, who have been overwhelmed by the interest. The New Brunswick government recently announced that it would move early entry into French immersion to Grade 1 from Grade 3, fulfilling an election promise. In some districts in British Columbia, parents line up outside school doors to ensure that their children can get a spot in the program. And some Ontario boards have put a lottery system in place to contain the exploding growth, with the unlucky forced to spend the school year in English-only classrooms.

But as the program has become the preferred destination for families looking to give their children a competitive edge or fluency in a second language, it has also gutted the regular English program.

Mineola is a small school. About three-quarters of its students are enrolled in French immersion, 60 of them in Grade 1. There are only two students in the Grade 1 English stream. One of them is Ms. Taylor's son, six-year-old Cameron. He's in a split classroom, sharing space with Grade 2 and 3 students. Ms. Taylor said Cameron struggled in reading and writing and staying in the English program has benefited him.

One Ontario school board trustee says the problem is so acute that the provincial government needs to step in. Unlike most other provinces, Ontario allows school boards to decide when to start French immersion. Most boards offer it in kindergarten or Grade 1.

But the Halton District School Board, west of Toronto, recently voted to delay entry to Grade 2 so parents can take an extra year to decide if it's the right fit for their child. The board also hopes the move will help manage the growth over time.

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Joanna Oliver, a trustee in Halton, says the Ministry of Education could create policy on when the program should start and how it should be delivered. As it stands now, principals struggle to find experienced teachers to satisfy the demand while trying to keep the English program viable.

"The Ministry of Education is responsible for development of the curriculum, including how much time is spent on numeracy and literacy per day. I think there is a role and opportunity for the Ministry of Education to set out a framework for French immersion," Ms. Oliver said.

But Heather Irwin, a spokeswoman for the ministry, said the government has no plans to get involved.

"When it comes to making decisions about optional programming, including the provision of French immersion, we believe our school boards are in the best position to make decisions that support local needs," she said in an e-mail.

The lack of provincial direction has resulted in school districts being left to "experiment" with how to deliver the program, Ms. Oliver said.

The Peel District School Board, to which Mineola belongs, took the controversial step four years ago to cap French immersion at 25 per cent of Grade 1 enrolment and to use a lottery system when the number of students applying for the program exceeds the available spots at a particular school. The measures were put in place because the board struggled to find enough French-speaking teachers to meet the high demand.

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Janet McDougald, the board chair and school trustee for Mineola, said Peel is reviewing the policy, with a report expected at the end of 2017.

The review could affect Mineola, she added.

Ms. McDougald said she understands that parents want to keep their neighbourhood school, but with so few families choosing the English stream, the board struggles to provide staffing and resources for such a small number of children. School boards receive per-pupil funding from the government, and it's more difficult to bring English resources into a school that has a large French-immersion population.

"I was hoping Mineola … parents would choose the English program to save the neighbourhood school, but currently this does not seem to be the case," Ms. McDougald said.

This concerns Ms. Taylor. She attended Mineola and wants her children to walk to school, as well.

"It does appear that the community is speaking and we do want French. But there are a very few of us who know it's not suitable for our children," she said. "And I'm really alarmed by the fact that my two children may be displaced because of the issue."