AUGUSTA — The U.S. Department of Education announced Monday that Maine’s application for a waiver under the Elementary and Secondary Education Act has been granted, allowing the state to implement another school accountability measure separate from the A-through-F grading system unveiled earlier this year.

The two-year waiver means that Maine is exempt from the strict and virtually unattainable guidelines of the 2001 No Child Left Behind Act, which decreed that 100 percent of students nationwide reach proficiency in math and reading by 2014.

No Child Left Behind, which became the Elementary and Secondary Education Act under the Obama administration, has been criticized for demanding 100 percent proficiency, the failure of which would result in federal sanctions. About 67 percent of Maine’s elementary students and 48 percent of high school students have achieved proficiency in reading and math benchmarks, which have become incrementally tougher since the implementation of the act.

Instead, Maine will be allowed to work toward the goal of halving the percentage of nonproficient students and raising the graduation rate at Title 1 schools to 90 percent over the next six years. Title 1 is a federal designation for schools with high levels of low-income or otherwise disadvantaged learners. There are 380 Title 1 schools in Maine, though all schools will be eligible for state and federal resources under the new system.

According to a news release from the Maine Department of Education, whose officials have been saying for months the waiver decision was imminent, the approval came after 11 months of negotiations with federal education officials. Under the new system, which builds on the state’s already-implemented Learning Results benchmarks, schools will be placed in five categories based on their performance: priority, focus, monitor, progressing and meeting. Schools in “priority” and “focus” status will be assigned a school improvement specialist and all schools will receive help developing educator evaluation and support systems that will be introduced in 2014-15 and fully implemented by 2015-16.

The Maine Department of Education will put schools into categories and publish the list in September. Education Commissioner Stephen Bowen expects approximately 60 schools to be in the two lowest categories.

Aside from the A-through-F grading system implemented by Republican Gov. Paul LePage’s administration, schools already are subject to ranking under the Elementary and Secondary Education Act. Schools that fail to meet federal requirements for two years running are put into a status called Continuous Improvement Priority Schools, though that label will give way to the new system under the waiver. The letter grading system will continue because it meets a requirement under the waiver that the Education Department publish periodic report cards for all schools.

LePage hailed the system set up by the federal waiver.

“Maine students deserve high standards, quality teachers and schools that are held accountable for their results,” said LePage in a prepared statement. “This flexibility from the federal government’s one-size-fits-all approach allows our state to stay focused on working toward that through the comprehensive reforms we already have underway — rewarding good schools and helping the ones who aren’t doing well.”

Maine is the 40th state since 2011 to be granted flexibility under the Elementary and Secondary Education Act. Bowen, who went on an extensive listening tour through Maine before submitting the waiver application, said the waiver gives Maine more freedom and resources to implement targeted interventions.

“This waiver marks an important turning point away from the stagnant achievement we’ve seen since No Child Left Behind was imposed in 2001 and toward a future where transformed student-centered schools are meeting the needs of the young people they serve, who are graduating truly prepared for success in college, career and civic life,” he said in a prepared statement.

In a letter to educators on Monday, which was provided to the Bangor Daily News by the department, Bowen said the waiver granted Monday differs substantially from the original proposal submitted in September 2012 and that his staff has written 10 versions of its waiver application in response to “evolving expectations” from the U.S. Department of Education.

“It has been a frustrating process, but worth the effort,” wrote Bowen. “This will be good news for all of us, especially since it will allow us to focus our time and resources helping schools with the greatest need instead of spreading the limited resources so thinly around all Title 1 schools that they would be unlikely to improve student achievement.”