In September, low water levels made transporting goods down the river more challenging and moved a wedge of saltwater upstream. In the summer and early fall of 2023, months of high temperatures and drought dried up the Mississippi River. In September, low water levels restricted the movement of barges down rivers and threatened drinking water supplies for some Louisiana communities, the Associated Press reported.
Water levels are particularly low near Memphis, Tennessee. The image below shows what the Mississippi River looked like near Memphis on September 16, 2023 (top) and September 10, 2021 (bottom). The river water in 2023 has become significantly thinner, exposing part of the river bed.
This is the second year in a row that drought has caused water levels in many Mississippi River gauges to drop to near record lows. On September 26, 2023, the river level at a gauge in Memphis was -10.26 feet, close to the record low level of -10.81 feet measured at the same location on October 21, 2022. This is the lowest water level since the National Weather Service began keeping records in 1954. Water level or "gauge height" does not indicate the depth of a stream but is measured from a selected reference point. This is why some water gauge height measurements are negative.
Farther upstream, water levels in New Madrid, Missouri, have been around -5 feet since early September 2023, near the minimum operating level. Water levels in the Mississippi River usually drop in the fall and winter, but in 2022, the river did not reach such low levels until mid-October.
A hot, dry summer is the main reason water levels will drop so low in 2023. Globally, summer 2023 temperatures will be 1.2 degrees Celsius (2.1 degrees Fahrenheit) warmer than average. The US states of Louisiana and Mississippi experienced their hottest Augusts on record, according to the National Oceanic and Atmospheric Administration (NOAA).
The U.S. Drought Monitor map above, a collaboration between the U.S. Department of Agriculture, the National Oceanic and Atmospheric Administration, and the University of Nebraska-Lincoln, shows conditions for the week of September 20-26, 2023. The map depicts drought intensity in progressive shades from orange to red. The map is based on an analysis of climate, soil and water condition measurements from more than 350 federal, state and local observatories across the country. NASA also provides measurements and models that aid drought monitoring efforts.
That week, about 38% of the contiguous United States experienced drought. States along the Mississippi River Basin have been starved of precipitation for months, temperatures have remained high and soil has seriously dried out. The Drought Monitor reports that as of September 24, 80% of Louisiana soils were dry (short or very dry). And in most states in the valley, more than 50 percent of the topsoil is dry or very dry.
Shallow water conditions along the river disrupted normal cargo transport. According to the Associated Press, barge companies reduced the carrying capacity of many cargoes in September because the river was not deep enough to accommodate the normal weight. The cost of shipping grain south from St. Louis is up 77% from the three-year average, according to the Associated Press.
A lack of fresh water flowing into the Gulf of Mexico has allowed saltwater to flow up rivers and into some water treatment plants in southern Louisiana, according to the Associated Press. Some areas of Plaquemines Parish are on a drinking water warning list and people have been relying on bottled water for cooking and drinking since June.
It would take a lot of rainfall to flush out the salt water from the Plaquemines River. The forecast from the National Weather Service's Lower Mississippi River Forecast Center is grim. If there isn't enough rainfall before mid-to-late October, saltwater could flow into New Orleans.