NEW ORLEANS -- Mayor Mitch Landrieu says he doesn’t know why two of his top deputies failed to “ring the bell” of alarm and inform him of an emergency in March in which all four of the Sewerage and Water Board’s 25-cycle power generators were out-of-service at once.

That happened months before failures of the unique, old-fashioned turbines compromised the city’s drainage pumps during two major rainstorms, but city leaders say they were not aware of the initial emergency until a WWL-TV report Monday.

“That issue was not brought to me,” Landrieu said at a news conference Wednesday. “If someone brought to me an issue that said all the turbines are out, the city is at risk, we would have been taking the actions that we are taking right now.”

Sewerage and Water Board Executive Director Cedric Grant, a part of the mayor’s executive team, wasn’t just aware of the emergency; he was the one who reported it at meeting of the S&WB’s Finance Committee on March 13.

“They lost the ability to produce 25-cycle power on March 7,” Grant told the committee members as he asked them to declare an emergency and approve $500,000 in repair contracts.

He started laughing as he explained further: “Basically, we’re fixing some turbines.”

The committee chairman at the time, Scott Jacobs, translated: “The lay summary is, we were headed toward a blackout.”

S&WB General Superintendent Joe Becker was even more explicit about what happened: “For a period of time we weren’t generating any 25-cycle -- we didn’t have any ability to produce power at the Sewerage and Water Board.”

MORE: Turbines failed in March; Landrieu never notified

Grant, Jacobs and Becker have all announced their resignations during the intense blowback from major flooding Aug. 5.

But the full explanation of what happened in March came only at the March 13 committee meeting. At the full S&WB board meeting two days later, Jacobs’ brief and dispassionate description was far more cursory.

“If anyone wants to hear further on that, we can certainly talk about that, but there was an emergency declaration and the committee approved the ratification of that declaration and the contracts that would be involved therein,” Jacobs said, quickly moving on to the next item the committee discussed.

Nobody asked any further questions, and Landrieu’s designee on the board, Chief Administrative Officer Jeff Hebert made the motion to approve the committee’s report.

Asked why Hebert didn’t tell him, Landrieu said, “I don’t know the answer to that question. It causes me concern. The chairman pro tem was there. Other board members were there. It was a public meeting. The press never reported on it. And so it’s an issue we have to look at. But this is what ringing the bell looks like.”

Hebert told WWL-TV he approved the report, but its full significance wasn’t made clear to him.

“I definitely was the first person to make a motion to make that repair, but it was never discussed in the context of, this will impair the entire system of electricity for the entire Sewerage and Water Board," he said.

According to Hebert, there was much more information and discussion in July when yet another emergency was declared after a turbine went down at the S&WB power plant.

Landrieu said he wants to wait until an "after-action report" is complete before he can say for sure why he was not notified about the March emergency, but ultimately, he said, the buck stops with him.

“I just want the public to understand, I’m ultimately responsible. I’m the mayor of this city,” he said. “We’ve been in partnership with the City Council and a lot of great people in one of the greatest rebuilds we’ve seen in a very long time, and we’ve gotten a lot of great stuff done. But this was a failure. There’s no way around that.”