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Does the Mississippi River look low? Your eyes aren’t deceiving you. And it’s going to get worse.

September 8, 2023   The Times-Picayune

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The already-low Mississippi River is set to reach levels so low by the end of the month that some decades-old records could be broken.


A report released Wednesday by the Lower Mississippi River Forecast Center said there's been a lack of rain over the entire Mississippi River basin, which includes part or all of 31 U.S. states and two Canadian provinces. That has caused the river to drop to near-record lows in multiple states.


In Louisiana, at least one record is expected to fall, while others are expected to come close. Recent drought years that resulted in low river levels include 2000, 2012 and 2022, and forecasters said it was likely that those years' record low river levels would be challenged or exceeded.


"It doesn't look so far that it's going to break some of our older records, which go back to 1988. That was the last time we had a significant drought," said Julie Lesko, senior service hydrologist for the National Weather Service in New Orleans.


The state's major river gauges are at Red River Landing in Pointe Coupee Parish, in Baton Rouge, and at Carrollton in New Orleans.


At Red River Landing, the river is now at 19.3 feet. However, it's expected to fall to 12.6 feet within the next month, which is below the record low of 13 feet.


The current stage at Baton Rouge is 6.8 feet, but it's forecast to reach 4 feet, which is lower than last year's stage but still above the record low of 3.4 feet set in 2012.


New Orleans is currently at 2.94 feet. The river is forecast to reach 1.7 feet over the next month, barely higher than the 1.1-foot record low set in 2000.


Lesko said a low river can cause a number of problems. Perhaps the biggest impact is on shipping: Barge operators can find it difficult to navigate around sandbars when the river is so low, making them pause travel. The same goes for other big ships traveling the Mississippi.


In the past, when the river's levels have dipped precipitously, the Coast Guard has published advisories recommending that ships with heavier cargo reduce their loads to avoid hitting sandbars. As of Friday, there were no advisories for shipping vessels.


"Based on the current forecasts of the river, we're continuing to monitor and see if additional measures will need to be taken," said Matt Roe, public affairs officer for the Army Corps of Engineers.


The Port of New Orleans has yet to see any impact to its traffic, officials said, in part because of ongoing efforts to make the river's channel at least 50 feet deep from the mouth of the river to Baton Rouge.


A low river can also affect river communities' ability to draw drinking water from the river, because saltwater from the Gulf of Mexico moves up the river when the current is slack. So far, Plaquemines Parish is the only community to feel an impact.


"Saltwater is more dense than freshwater," Lesko explained. "So, basically, a saltwater wedge moves up the bottom of the river and gets into the drinking water supply."


Typically, when there is a threat of this saltwater wedge moving up the Mississippi, the Corps builds a saltwater sill at the bottom of the river to stop or slow its progress. In July, the corps built a saltwater sill at 63 miles above Head of Passes.


"Saltwater intrusion is a naturally occurring phenomenon," Roe said. "The riverbed is below the natural sea level for quite a ways up the river. Usually, the river flows are high enough to push saltwater down."


According to the Corps, the saltwater wedge is currently at 30 miles above Head of Passes — meaning it's still a ways downriver from the sill — but it's expected to move upriver in the coming weeks.


"The location [for the sill] was selected based on optimal construction, and we dredged material upriver from the construction site to essentially build an underwater levee," said Roe. "As it moves up, the toe of the wedge hits this sill and the sill arrests the progression of the wedge."


For river levels to rise to normal again, Lesko says the Mississippi River Basin has to cool down, and it has to get slightly above-average rainfall for a period of time.


"We can bounce back, but it's not going to be instantaneous," said Lesko. "We don't need to see these record high temperatures because that just dries out things quicker. And that's what shuts off the rain."