D.C. Mayor Muriel E. Bowser (D) and Schools Chancellor Antwan Wilson. (Ricky Carioti/The Washington Post)

Teachers in D.C. Public Schools would receive salary increases of 9 percent over three years under a proposal unveiled Monday to end a labor impasse that has lasted since their last contract expired in 2012.

If ratified by union members and approved by the D.C. Council, the tentative agreement would cement the school system’s reputation for offering some of the nation’s highest average teacher salaries.

The proposal marks a political win for D.C. Mayor Muriel E. Bowser (D), who is up for reelection next year.

“I am so pleased to say that we have a deal,” Bowser said as she announced the agreement alongside D.C. Schools Chancellor Antwan Wilson and Washington Teachers’ Union President Elizabeth Davis.

“We know that teachers aren’t in it for the money. I recognize very clearly that they’re in it because they love children,” Bowser said. “What teachers also want is respect, a seat at a table and to be acknowledged for their expertise . . . and that’s what we want, too.”

The agreement would be retroactive to last October and include a 4 percent increase for the year that ends Sept. 30, with increases of 3 percent for the next fiscal year and 2 percent for the one after that.

The proposal amounts to an average increase of 1.3 percent per year from 2012 — the last time base salaries were increased — to 2019.

The contract does not cover teachers who work in public charter schools.

Davis called it the beginning of a new relationship between teachers and the school system. The old agreement expired under the previous DCPS schools chancellor, Kaya Henderson. Her successor, Wilson, took office in February.

Davis praised Wilson as a “man of his word” who had told her upon his arrival that reaching a contract agreement was his top priority.

“This contract signals to our teachers that Chancellor Wilson wants to work more collaboratively with them,” Davis said in an interview. “That means a lot. In the past, that has not been the case.”

Wilson said he thinks that the salary increases would not only help attract excellent educators from elsewhere but also would help the school system retain its best teachers. “We want to make sure we’re in the business of developing and nurturing talent,” he said.

Wilson said the District has the highest first-year teacher salary in the nation — $51,500 a year — and the fastest path to six-figure earnings. The new agreement builds on that, he said, raising starting salaries to $56,313 by the 2018-2019 school year.

Wilson has plenty of negotiating experience. During his confirmation process, he touted the signing of a contract with teachers in Oakland, Calif., that gave them their largest pay increase in more than 10 years.

The D.C. pay raises would cost $61.6 million over three years, officials said. An additional $51.2 million would be allotted to public charter schools, officials said, to satisfy a legal requirement for funding equity.

Money needed to cover the new spending would largely come from stronger-than-anticipated revenue growth, officials said. The chief financial officer’s June forecast showed the District will bring in an extra $132.3 million in revenue through fiscal year 2019, money that city officials said would be dedicated to paying for the teachers’ contract.

Council member and finance committee chairman Jack Evans (D-Ward 2) sounded a cautionary note about assuming the raises could be paid for exclusively through surplus revenue.

“The easy thing about it is we don’t have to cut anything to do it,” Evans said of the contract. “We’re going to do it from prospective revenue coming in from our great economy. If the economy slows, then we are going to have to identify other sources of revenue, which means you’re going to have to cut something.”

However, Evans said the council had already anticipated using excess revenue for teacher pay when it finalized its $13.9 billion budget in June. And the benefits of settling the negotiations outweigh any uncertainty about how the deal will be paid for, he said.

“I’m glad we got it all done. It’s been years,” he said. With the contract hashed out, he said, “instead of the city and the unions fighting, you have the city and labor focusing on who’s going to educate the kids.”

David Umansky, spokesman for D.C. Chief Financial Officer Jeffrey S. DeWitt, said sufficient revenue should be available for the proposed pay increases by the end of the current fiscal year.

However, before DeWitt can produce the fiscal impact statement required for the teachers’ contract, the council will have to pass legislation that allots the projected surpluses to teacher pay, Umansky said. He said the council would also have to revise legislation earlier this year that barred a 3 percent increase in per-pupil spending on schools from being spent on teachers’ raises.

The union’s more than 4,500 members will vote over the next two weeks on the proposal, which would then go to the council. If approved, teachers would receive lump-sum checks that reflect the retroactive salary increase.

In addition to the pay increase, the agreement includes a new program called D.C.: STAR aimed at giving teachers input into how to improve schools. Under the program, teachers at each school would vote to decide whether to extend the school day or school year — or adopt any other approach that would require changes to the contract’s work rules.

Davis, the union president, said the years-long contract stalemate has been tough on teachers, who watched salaries stagnate as the cost of living in the city rose quickly.

Teacher salaries in the District vary depending on experience, education and effectiveness ratings.

A decade ago, teachers faced a career maximum of $87,000, a pay level that required a PhD and 20 years of experience, said Michelle Lerner, spokeswoman for the school system. Now the career maximum is $126,000 a year, which would rise if the contract is approved.