Hundreds of Baltimore-area immigrant students and many others statewide may need to repeat or take additional English language classes next school year after state education officials retroactively raised the standards for English proficiency.

State officials say the change, implemented in May, was needed to ensure students are prepared academically, but the new standard means more students must remain in ESOL, or English as a second language, classes, creating a backlog in the pipeline for moving the students through the program. It also threatens to burden school systems with additional costs.

The decision by the Maryl `and State Department of Education, made after most school systems approved their budgets, increases the score a student must receive on an academic proficiency exam in order to leave the ESOL program.

As a result, school district administrators across the state are scrambling to reassign teachers and make other adjustments to keep pace with the growing size of ESOL classes. There are 68,000 students learning English statewide.

In Baltimore County, about 850 students would have moved out of ESOL classes this coming year under the former standard. Under the new standard, fewer than half that number —roughly 410 — will, said Brian Schiffer, who overseas ESOL as part of his job as director of social sciences and fine arts.

City school officials said they had not yet calculated the numbers, but that they knew the impact would be significant.

For more than a decade, English language learners have needed to pass a national proficiency test known as WIDA, or World-class Instructional Design and Assessment, before they can move out of ESOL classes, which focus on English grammar, reading and writing. The students usually take classes in other subjects at the same time, all of which are taught in English.

Susan Spinnato, director of instructional programs at the state education department, said the state is part of a consortium that uses WIDA and decided to update the test about a year ago to align it with the more rigorous Common Core initiative to establish an educational standard and ensure high school graduates are prepared for college and the workforce.

At Patterson High School, which has a large population of immigrant students, only one student passed the test out of hundreds who took it during the school year that ended earlier this month, according to Margot Harris, who heads the school’s English as a Second Language program. The student who passed, she said, is an honor student in the top 5 percent of his class.

Harris said that although raising the standard may have been necessary, it was unfair for state officials to do so at the end of the school year, long after students had taken the test. Students who took the test believing they would be leaving the ESOL program were upset, she said.

Even some Patterson students who were able to earn a high school diploma this year did not pass the WIDA exam, Harris said. High school students who recently arrived in Maryland could have difficulty amassing enough credits to graduate if they spend less time in regular classes because they remain in ESOL classes, she said.

She said the test, which measures listening, speaking, reading and writing abilities, is so tough that many native English speakers could not pass it.

“We expect the impact to be significant,” said Janise Lane, executive director of teaching and learning in the Baltimore city schools. “It is a common issue that all of the districts are struggling with.”

ESOL teachers, whose job evaluations are based in part on test scores, also will be affected by the policy change and judged on a different standard than was in place when the school year began.

Lara Ohanian, director of differentiated learning in the city schools, said students in ESOL classes won’t receive the same level of services they had in the past because the increased number of students will dilute the available funding.

This coming school year, the performance of English language learners will have a much greater impact on how schools are judged under the federal Every Student Succeeds Act. That law sets guidelines on how schools will be held accountable for student performance.

Spinnato said the state hopes to work with school systems to find creative ways to handle the additional pool of students in ESOL classes next year within budget constraints.

For Baltimore County, the tougher standards come as the school system added more than 800 new English learners to its student rolls between October 2015 and 2016. Most of the influx of new students were refugees, undocumented immigrants from Central America, and native born children from families that speak only Spanish at home.

With the number of immigrant students increasing each year, Baltimore County hoped class sizes could be lowered by hiring additional teachers.

Now, Schiffer said, “we won’t be able to get the same bang for the bucks.”