9 October 2023
By Greg LaRose
Contributing Writer
(lailluminator.com) — Updated river flow forecasts and effective containment in the Mississippi River have slowed the predicted progress of salt water flowing upstream. It’s to the point that officials Thursday (Oct. 5) optimistically pushed back expected impacts to drinking water supplies on the New Orleans west bank and Gretna a full month.
Plus, they now say salinity levels won’t reach the health hazard level for the entire New Orleans east bank or the rest of West Jefferson. Still, preparations will continue in anticipation of some level of saltwater intrusion, just not to the degree parts of lower Plaquemines Parish have experienced for the past few months.
Prolonged drought conditions throughout the Mississippi and Ohio river valleys have curtailed the flow of fresh water downstream, allowing denser salt water from the Gulf of Mexico to creep into the delta and upward. Residents of Port Sulphur and Pointe a la Hache near the mouth of the river have relied on bottled water for several weeks.
Officials provided an update on the saltwater intrusion on Thursday morning of last week at the Corps of Engineers headquarters in New Orleans, just downriver from the east bank water intakes.
Salt water was originally expected to reach Algiers and Gretna in late October. New predictions from the U.S. Army Corps of Engineers now place the arrival dates at Nov. 23 and 26, respectively.
Gretna operates its own waterworks, independent of Jefferson Parish.
Col. Cullen Jones, commander of the Army Corps’ New Orleans district, said the saltwater wedge is currently just downriver from Belle Chasse and hasn’t moved for the past week, when work began on expanding an underwater sill to restrict the upstream flow of salt water. The conditions have allowed the work to progress ahead of schedule, with completion now expected to conclude on Thursday of this week.
Salt water topped the sill Sept. 20 but has remained “static” at river mile marker 69.4, Jones said. It’s projected to reach Belle Chasse this Friday, the same date as the original forecast. The new outlook puts salt water at the Dalcour waterworks (mile marker 80.9) on Oct. 17, two days later than first predicted, and at Chalmette’s water plant (mile marker 87.9) Oct. 28, or nine days past the earlier projection.
Increased flow of fresh water downstream is also keeping the salt water at bay, Jones said. The original forecast anticipated water flowing at a rate of 145 cubic feet per second (cfs), but he said actual flow has been somewhat higher. The National Weather Service’s 28-day forecast has slightly increased its low-end flow predictions, which Jones said are based on only two days of rain in October and none in November. Any rain beyond that would have a favorable impact on the flow rate, he said.
Water with 250 parts salt per million (ppm) is considered unsafe for individuals with high blood pressure. The Sewerage and Water Board is striving to keep salinity levels between 40 and 60 ppm. Exposure to salt water corrodes metal five times faster than fresh water.
The Sewerage and Water Board of New Orleans will continue with its plan to bring fresh water from upriver to its intake in Algiers to dilute the water it uses from the river. SWB Interim Superintendent Ron Spooner said the agency will continue to seek bids for a pipeline to supply fresh water to its Carrollton treatment plant on the east bank, and now it has more time to do so with the new forecast.
“Hopefully, we don’t have to implement the pipeline, but we still have to plan for that,” Spooner said.
Jefferson Parish President Cynthia Lee Sheng said she will move forward with plans already in motion to install a “lay-flat” pipe, which looks like a large fire hose, along the riverside to bring down fresh water from above Kenner.
New Orleans will need a more durable pipe to cover more distance on the east bank. Spooner said bids are being submitted for the project.
Local officials are motivated to carry on with their saltwater abatement plans because President Joe Biden has issued an emergency declaration for the parishes on the lower Mississippi. It ensures the federal government will cover at least some of the cost to keep the drinking water supply safe, although a string of recent disasters has depleted the Federal Emergency Management Agency’s disaster relief fund.
On Thursday of last week , the New Orleans Office of Homeland Security and Emergency Preparedness streamed an online update on saltwater intrusion for business owners in the city. Anna Nguyen, NOHSEP’s public information director, alluded to “great news” coming later in the day regarding updates to the saltwater arrival timeline.
Participants in the Zoom meeting pressed Nguyen and other city and Sewerage and Water Board staffers who took part for guidance on how to avoid anticipated losses from saltwater intrusion. Many said they were restaurant owners worried about food preparation and possible damage to their equipment that uses water. Some wanted to know whether they should purchase reverse osmosis filters, find outside ice sources or plan to shut down entirely.
Nguyen was measured in her responses, urging business owners and residents to “stay connected” for the latest updates and think ahead about their needs, such as arranging vendors to provide ice and water. She discouraged panic water buying at grocery stores and said the Sewerage and Water Board would notify the public far before salinity levels reached unhealthy levels.
This article originally published in the October 9, 2023 print edition of The Louisiana Weekly newspaper.