Sara Luse works at the bar at Sally's Middle Name in Washington on June 3. The restaurant has already moved to a $15 hourly wage. (J. Lawler Duggan/for The Washington Post)

D.C. lawmakers on Tuesday gave final approval to a bill that will ramp up the city’s hourly minimum wage to $15, lifting pay for most low-income workers in the city to among the highest in the country by the end of the decade.

The District’s hourly minimum, now $10.50, was already scheduled to rise to $11.50 in July. Under the measure passed Tuesday, it will continue to increase by about 70 cents a year until it reaches $15 in 2020. After that, annual increases would be automatic and tied to inflation.

The unanimous vote by the D.C. Council marks a victory for Mayor Muriel E. Bowser (D) who had proposed the bill and cast the pay increase as among the most important things she could do as mayor to improve living conditions for the city’s working poor.

By championing the measure, Bowser was also able to forestall a broader $15 minimum wage ballot measure that appeared increasingly certain to qualify for the city’s November ballot and that was fiercely opposed by the city’s powerful restaurant industry lobby.

Instead of guaranteeing tipped workers $15 an hour plus tips, the bill stipulates that the base rate for those workers will increase to $5 an hour from $2.77 an hour over the same period. After that, tipped workers’ base pay will be tied to inflation. Employers in the District would remain responsible for paying employees the difference between their base pay and the minimum wage if tips do not make up the gap.

On Tuesday, two D.C. Council members spoke out against continuing a split wage system for tipped workers. “I’m not happy about where we ended up on tipped workers,” said Council member Elissa Silverman (I-At large). Silverman said the law would make it harder for many single women and working parents to count on a predictable income from tipped jobs. She also said she found the arguments of the restaurant industry unconvincing, since some big states, like California pay restaurant workers the same minimum wage as other workers.

“Seven other states have no tipped wage at all, and restaurants seem to be doing just fine,” Silverman said.

Council member Vincent B. Orange (D-At large), who led negotiations on the bill and who lost his reelection bid last week, held up the vote as proud final piece of legislation.

“This will help an enormous number of workers in the District of Columbia,” he said.

According to one estimate, the measure would mean a raise for 70,000 janitors, parking attendants, dishwashers and others, and it probably would put upward pressure on the wages of 44,000 more workers who are paid slightly above the new baseline.

But critics say a $15 minimum will be an order of magnitude larger than any previous wage floor and could prompt businesses to lay off workers, reduce their hours or increase automation, such as self-serve kiosks.

A survey by the city’s hospitality industry also warned that many businesses would consider leaving Washington for Virginia, where low-wage workers are paid the federal minimum of $7.25 an hour. The federal rate has remained unchanged in seven years and is the standard in 20 other states.