Cedric Grant, one of Mayor Mitch Landrieu’s top deputies, will officially take over the top job at the New Orleans Sewerage & Water Board this month as the agency embarks on more than $3 billion worth of infrastructure improvements.

Grant, who has been earning about $164,000 a year as Landrieu’s deputy mayor for facilities, infrastructure and community development, will get an annual salary of $210,000 in his new role, amounting to a 28 percent raise.

He replaces Marcia St. Martin, who retired early this year after a four-decade career with the city.

It’s not clear yet how or whether Grant will be replaced at City Hall, or whether he will ultimately give up all of the responsibilities he held there.

Landrieu spokesman Tyler Gamble pointed out that under Grant’s watch, the city’s Department of Public Works has begun to work more closely with the Sewerage & Water Board in coordinating their efforts — an indication that the Mayor’s Office may not see a firm demarcation between the agencies as necessary or ideal.

“It will be a little more clear once he starts what happens as far as responsibility for the departments and agencies that he managed,” Gamble said.

After months of questions about whether Grant could accept the new position under state ethics laws, the Sewerage & Water Board voted unanimously Wednesday to install him in the job effective July 28.

For the past few years, Grant has been serving as a stand-in at the board’s meetings for Landrieu, who by law serves as board chairman. State ethics law bars anyone from leaving a public board then accepting a job or contract with that board within two years.

Landrieu’s administration argued that Grant’s appointment would not really violate the law because he served only on behalf of the mayor, not as an independent board member. But the state Ethics Board disagreed, so Landrieu asked the Legislature to carve out an exception in the law for him, and Gov. Bobby Jindal signed it into law last month.

In a prepared statement Wednesday, Landrieu said, “There is no person better prepared to take on the task of modernizing this critical public utility.”