Unsafe levels of saltwater are expected to reach New Orleans-area drinking water systems in the middle of next month, as officials scramble to deal with a mass of saltwater making its way from the Gulf of Mexico up an extraordinarily low Mississippi River.
Gov. John Bel Edwards said at a Friday afternoon press conference that federal, state and local officials are “making plans for a duration of an event and a severity of an event” that will exceed a similar saltwater intrusion in 1988.
Edwards said substantial rainfall far upriver in the Midwest is needed to replenish freshwater here, but none is in the forecast.
"The forecast is for an above-average amount of precipitation in the winter. But that's still several months away," Edwards said.
Although the Army Corps of Engineers is working to elevate an existing underwater sill downriver of New Orleans, officials said that measure will only delay, not stop, a saltwater “wedge” that is currently forecast to reach Belle Chasse on Oct. 13. Because saltwater is heavier than freshwater, the saltwater at the bottom of the water column moves up the river faster.
Officials are planning to ship millions of gallons of freshwater from upriver to mix with the saltier water at intake pipes, reducing salinity to safe levels. The Corps so far has assembled enough privately contracted barges, as well as some owned by the government, to initially ship 15 million gallons of freshwater next week. Officials said 36 million gallons daily will be needed to supply all plants as far upriver as Gretna.
"Are we confident that by the time we need the 36 million we can have it? We are," said Corps spokesperson Ricky Boyett. "Our target right now is, let's get 15 million flowing, and then we'll continue to bring it on."
Additional freshwater could be needed for the Carrollton plant in New Orleans, and in East and West Jefferson Parish. The needs for those facilities will become clearer over time, Boyett said.
Edwards stressed that other measures will be taken, such as installing reverse-osmosis purification equipment at affected plants.
"We're going to do what we always do in an emergency situation. We are going to go big and go quick. We can scale back later," Edwards said.
The saltwater wedge is currently forecast to arrive at local treatment plants on the following schedule:
- St. Bernard Parish: Oct. 19
- Algiers: Oct. 22
- Gretna: Oct. 24
- West Jefferson: Oct. 25
- Carrollton: Oct. 28
- East Jefferson: Oct. 29
Edwards urged residents not to overstock on bottled water, since there is no national shortage and vendors should have no problem restocking. He also said residents should be careful with how much tap water they use in coming weeks.
"We've got to make sure that people have drinking water; we ought not be out there watering our lawns with it," Edwards said.
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