Nearly a quarter-million residents on the east bank of Jefferson Parish were under a 42-hour boil water advisory last week due to a “perfect storm of events” that are unlikely to repeat themselves, Parish President Cynthia Lee Sheng said.
The episode began Thursday night, when the East Bank Water Treatment Plant, which is powered by two separate Entergy substations, lost electricity, triggering a series of back-up generators to kick on.
Given their size, it usually takes around two minutes for the generators to fully come online and sync up. Normally, the parish’s water towers are enough to maintain adequate water pressure during that powering-up period.
However, the water tower off David Drive — one of two major suppliers of water pressure on the east bank — was offline as part of a long-overdue rehabilitation.
That caused water pressure on the east bank to drop to 4 pounds per square inch for two minutes, well below the 20 pounds per square inch that triggers a boil water advisory.
“We believe that we could have kept the pressure up had the David Drive tower been online,” Lee Sheng said.
At dawn on Friday, the parish’s Water Department began collecting water samples to test for bacteria. Those samples had to sit for 18 to 24 hours before they could be tested for bacteria. At 1 p.m. Saturday, after the testing was complete, the boil water advisory was lifted.
“We couldn’t have done it any faster,” Lee Sheng said.
The rehab of the David Drive water tower was supposed to be done in May but was delayed, Lee Sheng said. The tower is one of 11 slated for a facelift under Jefferson Parish’s 20-year, $1.1 billion plan to upgrade its aging water system, paid for through a rate increase approved by the Parish Council in 2021. Repairs to the water tower off Causeway Boulevard — the other major tower on the east bank — were completed in 2021.
Outside of a hurricane, it is rare for both Entergy substations that provide power to the water treatment plant to go offline, Lee Sheng said. The outage happened around 6:30 p.m. after a severe thunderstorm rolled through Old Jefferson in Metairie.
The treatment plant is outfitted with four back-up generators with a total of 4.5 Megawatts of power. Lee Sheng said they're tested every month and are always turned on ahead of hurricanes.
Entergy spokesperson David Frees couldn’t say Monday whether both substations had lost power.
“The team in Jefferson Parish is looking into the details and will hopefully have a more robust answer sometime this week,” he said.
Boil water advisories are more common on the West Bank of Jefferson Parish, especially in Grand Isle and Lafitte, where water lines are more often struck by vessels.
The last major boil water advisory on the east bank of Jefferson Parish was in 2021, after the roots of trees knocked over by Hurricane Ida’s winds ripped through underground water lines. The boil water advisory wasn’t lifted until nine days after Ida made landfill.
A freeze in 2018 also led Jefferson Parish to issue a three-day boil water advisory on the east bank. It was the first widespread advisory since before Hurricane Katrina.
