Mayor Mitch Landrieu took an important step in consolidating control over the New Orleans Sewerage & Water Board, one of the city’s biggest agencies, on Monday, just a few days after hitting a major snag on that same front.

On the one hand, Landrieu nominated a new slate of members to join the board, which is being restructured in a way that will give his own appointees an overwhelming majority vote as the board gears up for hundreds of millions of dollars in upgrades to the city’s water and sewer infrastructure.

On the other hand, a sharply divided Louisiana Board of Ethics voted last week that Cedric Grant, one of Landrieu’s top deputies, cannot become the Sewerage & Water Board’s next executive director.

Grant, the deputy mayor in charge of facilities and infrastructure for City Hall, applied for the job with the mayor’s backing last year, and the board decided to offer him the position in December.

But the ethics board voted 6-to-5 on Friday that giving him the job would violate a state law that prohibits anyone from stepping down from a public board and then accepting a job or contract with that board within a two-year period.

While Grant has never been a formal member of the Sewerage & Water Board, he has served as Landrieu’s stand-in on the panel for much of the past three years. The mayor automatically serves as board president, but Landrieu rarely attends meetings in person.

It’s not clear yet how the mayor will respond to the ethics panel’s action. With Grant, he would have had an administration insider running one of the city’s quasi-independent agencies, and he offered no sign Monday of retreating on the issue.

“The Sewerage & Water Board selected Cedric Grant as the strongest and most qualified candidate for the job,” Landrieu’s spokesman Tyler Gamble said in an email. “Together, the city and S&WB are reviewing the opinion and considering our options.”

Next in line for the job, which in recent years has been one of the best paid in city government, would be Tracie Boutte, a vice president with Entergy Services Inc. The Sewerage & Water Board named Boutte as its second pick when it offered the job to Grant.

Whoever gets the position will lead an agency in transition, ramping up a major building program that will replace aging pipes and other infrastructure while a new set of directors steps in to provide oversight.

With Landrieu’s backing, the Legislature last year voted — and parish voters later agreed — to overhaul the Sewerage & Water Board’s structure, cutting the number of members, putting new term limits in place and requiring most members have certain professional credentials. Good government groups like the Bureau of Governmental Research had been pushing for the change in order to strip politics out of board decisions.

Under the new arrangement, Landrieu will have eight appointees on the board. As is the case now, two other members will come from the city’s Board of Liquidation, City Debt, which manages city bonds. Landrieu himself will bring the board to 11 members.

Landrieu stuck mainly with familiar names in picking new board members, all of whom were nominated by a committee made up of local university presidents and other civic leaders.

Three of the appointees — Kerri Kane, Marion Bracy and Mark Moody — already serve on the board.

Scott Jacobs, a local insurance executive and the husband of Leslie Jacobs, an influential local school reform advocate, already serves as one of Landrieu’s appointees on the board that governs the city’s pension fund for firefighters.

Robin Barnes is the chief operating officer at Greater New Orleans Inc., the regional nonprofit aimed at creating jobs.

Joseph Peychaud, one of two appointees who would serve as a “consumer/community advocate” and is therefore exempt from the new professional requirements, is the principal at St. Katharine Drexel Preparatory School, formerly Xavier University Prep.

The second community advocate would be Kimberly Thomas, described by the city as a funding project manager and public assistance program specialist with the local construction company Jacobs/CSRS.

Finally, Landrieu nominated Tamika Duplessis, a chemistry professor at Delgado Community College who also does research on breast cancer at Xavier University.

The mayor’s nominees are scheduled for a vote at the City Council on May 22.