Forecast Points To Possible Low-Water Relief

A long-range forecast indicating the potential for wet weather ahead means that low-water conditions could soon be improving on the Lower Mississippi.

Donnie Williams, chairman of the Lower Mississippi River Committee, noted that, since the first part of September, the industry has had some form of tow size or draft restrictions.

Industry is currently operating under draft restrictions of 10 feet, 6 inches southbound from Cairo, Ill., to Rosedale, Miss. (Mile 585) and 11 feet from Rosedale to the Gulf. Northbound, the draft was set at 10 feet from the Gulf to Cairo.

“We’re not at full capacity, but we just made the proposal to the Coast Guard to increase drafts [November 21] to 11 feet, 6 inches southbound all the way from Cairo to the Gulf and 10 feet, 6 inches northbound,” Williams said November 19.

Recent rainfall throughout the mid-Mississippi and Ohio basins has caused the river to rise above low-water thresholds at multiple gauges, and the 28-day forecast is also promising, he said. Plus, Williams cited recent years’ climate trends.

“Historically, you’ve got your low-water season of September or October and part of November, and historically, around mid-November, wetter rain patterns start to come into play, which we are seeing more of,” Williams said. “We start to come out of the extreme low-water conditions.”

The National Oceanic and Atmospheric Administration’s (NOAA) online river gauges showed the Mississippi River at Memphis at -7.57 feet and rising before beginning to fall again, but not as low as in previous months. The gauge data predicted a low of -5.7 feet, more than 2 feet above the low-water threshold at Memphis of -8 feet, on December 3, which is as far as the data was listed.

At Hickman, Ky., which has been a frequent trouble spot because of rock pinnacles in the riverbed, the river climbed above the low threshold of 1 foot November 17 and was expected to reach a high of 6.4 feet on November 24 before falling back to 1 foot around December 3.

The Cairo gauge, which measures the Ohio River, was expected to fall back to the 10.3-foot low threshold by November 30 and down to 9.2 feet by December 3, but Williams said that gauge is affected by peaking hours at hydroelectric plants upriver at Kentucky and Barkley dams.

“The Cairo gauge is very unpredictable,” he said. “It reminds me of an EKG, always up and down, and it makes it really hard to make draft decisions.”

Ultimately, Williams said, industry committees must consult multiple gauges several times throughout the day to make the best decisions. He added that NOAA’s Lower Mississippi River Forecast Center (LMRFC) has been “vital to us.”

The LMFRC released its latest guidance November 19.

“We are beginning to see what looks like a shift in the weather patterns that may bring more persistent relief to the low flow/stages,” said David Welch, development and operations hydrologist at the center.

Welch said longer-term rainfall forecasts anticipate additional rainfall behind the current river rise that could potentially keep the river at Cairo above 15 feet until mid-December.

“It is still a little early to call off the low flow/stages for this year, but the climatology for rainfall tends to improve as we head into December and January,” he said.

The LMRFC forecasts an expected low stage of 6.9 feet at Cairo for the remainder of the year, which was higher than in 2022 (4.8 feet), 2023 (4.5 feet) and 2024 (6.4 feet) but lower than in 2012 (7.2 feet). The historic low record was set at Cairo in 2023.

The historic low record in Memphis was also set in 2023 at Memphis, but this year’s forecast is for a seasonal low of -8 feet, again better than in 2022 (-10.8 feet), 2023 (-12.0 feet), 2024 (-10.3 feet) and also that of 2012 (-9.8 feet).

Williams noted that all dredges have moved out of the Memphis and Vicksburg engineer districts and back to deep water. As far as remaining problem areas, he noted that the Mat Sinking Unit has been working at Mile 680, which had restricted traffic during daylight hours, but that work was expected to conclude November 21, with the unit moving farther south and not expected to require additional restrictions. One “tight” area remained, at Mile 482 near Lake Providence in Louisiana, he said.

Williams praised the Coast Guard and Corps of Engineers for keeping the river open throughout the recent 43-day federal government shutdown

All considered, he said, “We’ve had a very good year,” despite facing low-water conditions for the fourth year in a row.

“We’ve had some groundings, but not a ton of groundings,” Williams said. “We’ve had dredging this year with the Corps of Engineers doing what they could do with limited funds and the government shutdown.”

Looking ahead, Williams said it will be important to watch the amount of rainfall in the Upper Mississippi Basin, especially with the navigation flow support season scheduled to end on the Missouri River November 22 at Sioux City, Iowa, and in the following days farther downriver, ending at the mouth of the Missouri near St. Louis on December 1. That could cause problems just downstream of the mouth, he said, especially if the Illinois River doesn’t receive forecast rainfall.