New Orleans is a water city. The city is built on a delta between a river and a lake, with muddy soil beneath us and ever-present humidity hanging in the air, and its moisture is part of our identity. This is why the drought-induced saltwater wedge threatening the city’s water supply has captured our attention and induced a panic-fueled run on bottled water. It feels strange and unfamiliar to us humid beings.
Drought? Salt water threatening the water supply? This is unfamiliar territory.
We are used to floods. For better or worse, flooding is part of life on a river delta. All the soil beneath us was brought here at some point by floods. As the city urbanized, we built levees to control flooding and inadvertently sank half the city below sea level. Now all the rainwater that falls inside the levees must be pumped out, and when the drainage pumps fail or the rain is too heavy for the pumps to keep up, we know which underpasses to avoid, and we know when to move our cars onto higher ground. It’s become second nature.
But drought? Salt water threatening the water supply? This is unfamiliar territory. We don’t know what to expect or how we should react. Despite authorities telling people not to panic, people are panic-buying cases of bottled water, discovering newfound expertise in reverse-osmosis filtration and sharing memes like the waterfall scene from “Mad Max: Fury Road.” A local media outlet even ran a story that suggested residents switch to using bottled water to wash their cars because of the corrosive properties of salt water. We are clearly out of our element here, and we do not know which fears are genuine and which ones might be overblown.
A few things are certain, however. The people of south Louisiana have reason to distrust authorities. This region is a sacrifice zone that has a long history of prioritizing industry and commerce over the health and well-being of communities. The federal levee failures of 2005 that coincided with Hurricane Katrina’s making landfall nearby are still fresh in our collective memory, and the wide-ranging environmental issues we face have not received enough attention or remedy.
And climate change is here. The weather is extreme, with higher highs and lower lows. The drought and the subsequent low flow in the Mississippi River can all be traced back to our carbon emissions. Yet we are still building liquefied natural gas export terminals, and the federal government is still opening up new leases for offshore oil and gas extraction.
So why is this happening?
As with many environmental issues here, the story involves the Army Corps of Engineers and the use of the river for navigation. The Corps maintains a minimum depth of 50 feet in the river to accommodate deep-draft vessels. The bottom of the river becomes higher than sea level only at around 350 miles upstream from the mouth of the river, near Natchez, Mississippi, which means the majority of the river bottom in Louisiana is below sea level.
As long as the river has a minimum flow of 300,000 cubic feet per second, the fresh water coming down the river keeps the salt water of the Gulf of Mexico from traveling up the river. However, when the flow drops below 300,000 cubic feet per second, a wedge of denser salt water begins to creep up along the bottom of the river. Because of the abnormally dry conditions across the Mississippi Valley this summer, the river flow at around 150,000 cubic feet per second is well below normal, and it may continue to drop further. This low flow has allowed the wedge to form and steadily work its way up the river. And it’s that river that New Orleans and numerous other communities rely upon for drinking water.
This year’s wedge is likely to be stronger and far more persistent than in years past.
While unfamiliar to many, this issue has occurred before, and it was even anticipated as part of the Corps’ river-deepening project. In 1988, a saltwater wedge made it to the city’s water intake. The Corps built an underwater sill across the river to slow down the wedge, but it was too late to have much of an impact. Barges of fresh water were brought down the river to dilute the salt in the municipal water supply to a safe level. The river also had low flow in 2012 and in 2022. Both times, the Corps built sills to slow the wedges, and the salt water never ended up reaching the city’s intake pipes.
However, this year’s wedge is likely to be stronger and far more persistent than in years past. Communities downstream from New Orleans, including those in Plaquemines Parish, are already experiencing impacts. New Orleans should expect impacts to begin in late October or early November if the river flow does not improve. Once again, plans are in place to ship fresh water downstream in barges to dilute the salt in the municipal supply to Environmental Protection Agency municipal water standards (250 parts per million chloride).
Still, there are a lot of unknowns and fears. Though the water will be safe for most people to drink, even with a noticeable taste, infants on formula and people with low-salt diets, such as those with kidney disease, should not drink the municipal water once the supply is affected. Farmers, especially citrus farmers, will need to modify their irrigation practices. And the salt may corrode pipes, leading to increased leaching of heavy metals from older pipes and accelerated wear and tear on appliances.
While these concerns should be taken seriously, the availability of bottled water is not expected to be an issue. There is no shortage of bottled water nationally or regionally. And it is expected that the water will be safe for cleaning and bathing.
So what should we do?
Instead of washing our cars with bottled water, let’s maybe not wash our cars at all.
While there is not much an individual can do to prepare for the impending salt water, we can install rain barrels for irrigation (which will also help with flooding when the rains return) and practice water conservation. Instead of washing our cars with bottled water, let’s maybe not wash our cars at all until this blows over.
Collectively, however, we have a ton of work to do. We must reduce our emissions drastically to limit climate change and mitigate these weather extremes from becoming even more of an issue in the future. We should replace all water lines that may leach heavy metals, such as lead, when the water chemistry changes. And we should work to remedy the environmental injustices that continue to harm our communities to this day. We must also work to better balance the uses of the river and negotiate competing interests like ecosystem restoration, flood risk reduction, commerce, fisheries and drinking water supply.
And just as this side effect of climate change probably came as a surprise to many people across southeast Louisiana, we should expect more of the unexpected moving forward: not just here in New Orleans, but around the world. If there is one thing we have learned here, it’s that throwing off nature’s balance can unleash chaos. We should be acting urgently to prevent that from happening, but we should also operate with the knowledge that change is already here.
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