The St. Bernard Parish Council voted 5-1 Tuesday night to increase water and sewer rates in the parish by 70 percent.

The council had discussed increasing the rates for most of the past year.

The parish last increased its rates in 1997.

After several adjustments to the proposed increases were discussed but failed to gain majority support, including staggering the hikes until 2016, the six council members at the meeting addressed the audience about the need for the higher rates.

They said they had to balance the need to update the parish’s aging water infrastructure with sympathy for residents who late in 2014 showed their disdain for the rising cost of government by rejecting a long list of millages — nearly all renewals — to pay for a variety of public services.

Under the rate increase approved Tuesday, residents using 8,000 gallons of water each month would see their combined water and sewer bills rise to $59.41 per month, up from $34.94 a month at present.

Councilman-at-large George Cavignac voted no, while Council President Guy McInnis was absent.

Cavignac said after the meeting that he wanted to see the rate increase staggered rather than applied all at once. “The projects are definitely needed,” he said. “There’s no doubt about it.”

The parish’s water infrastructure drew heavy scrutiny following the 2013 death of a 4-year-old boy who contracted a rare brain-eating amoeba, apparently on a Slip ’N’ Slide at a mobile home near Violet. Public health experts contended that insufficient chlorine levels likely contributed to the presence of the amoeba in parts of the parish’s water system.

In late 2013, state tests showed water supplies in several parts of St. Bernard — including near where the boy is believed to have been infected — had low chlorine levels. The parish then started flushing its water lines with additional chlorine to minimize the threat of the amoeba.

A consulting firm hired last year to evaluate the parish’s water infrastructure found that the system needed about $31 million in capital improvements, including $21 million to replace old, cast-iron water lines, largely in Arabi and Violet, that have a history of leaking.

The firm’s report said the parish’s water rates were too low by almost a third and sewer rates were 80 percent below operating costs, which prompted the effort to raise the rates. It also found that water usage in the parish was more than double the national average on a per-capita basis, likely due to a high number of heavy industrial plants.

In addition to needing infrastructure upgrades, the report said, St. Bernard’s water operations were significantly understaffed and regular maintenance had not been performed on the water system, which can lead to higher long-term costs.

Some experts suggested that St. Bernard’s sharp population drop in the wake of Hurricane Katrina played a factor in the water’s contamination. Because fewer residents are using the water, they suggested, it’s not moving as actively through the system.

Parish officials are working with the state Department of Health and Hospitals’ drinking-water revolving loan fund to replace the cast-iron water lines. The parish has identified 31 cast-iron segments of piping that are marked for high priority to be replaced, which would reduce water leaks.

Adding a new 20-foot water line extension along La. 46 also has been targeted as a way to reduce low-pressure problems and improve fire protection in lower St. Bernard, officials say.

Follow Richard Thompson on Twitter, @rthompsonMSY.