The U.S. inland river system is approaching historic levels of low water at the critical harvest time. Comparisons are being raised to the previous historic low water levels of 2012 and even 1988. River gauges are not at 1988 levels yet but could be by October 26 if rain relief is not forthcoming, according to projections.
The St. Louis gauge is at -2.4 feet below the reference plane and projected to reach -3.1 by October 26. Memphis stands at -8.65, projected to reach -9.4 by October 26. Cairo is at 7.26, versus a projected 6.8 by October 26. By comparison, Cairo reached 7.15 during the 2012 low-water event and 4.93 in 1988. Even more dire levels could be reached when the Missouri River flow from Gavins Point is cut off in November.
Just a few short weeks ago, some Western newspapers were renewing a quixotic campaign to divert Mississippi River water to the Colorado River and other parched Western rivers.
During each low-water event, as with floods, industry groups cooperate closely with the Corps and Coast Guard to mitigate their effects and speed cargoes on their way. The Corps dredge Hurley is clearing barge queues at Mile 681, but eight or nine spots remain to be dredged. Barge drafts are currently at 9 feet between Cairo and St. Louis.
The Corps of Engineers is doing everything it can with its dredges Hurley and Potter. But it’s not just about dredging. After emergency dredging, the Coast Guard must set new virtual or electronic buoys, then physical ones. It’s long been known that the Coast Guard does not have enough inland buoy tenders. New ones are in the works but are not scheduled to launch until 2025.
When virtual or e-buoys began to be introduced, they sparked a discussion about whether and how they might mitigate the need for physical buoys. It’s clear now that the need for physical buoys will never go away. Industry sources are reporting that it can take up to a week for the Coast Guard’s e-buoys to upload into their system to be available for download onto mariners’ navigation systems. The industry is discussing with the Coast Guard whether setting and loading their own e-buoys might be faster.
In the 1988 low-water event, tows were restricted to 16 barges at 9-foot depths. Today the navigation industry is able to operate with 25-barge tows at the same depths. Industry sources say that is partly thanks to improved river training structures put in place by the Corps since 1988—revetments and dikes that help the river self-scour by channeling its flow, thus widening the channel and reducing (but not eliminating) the need for maintenance dredging.
Low water levels expose not just sandbars, but critical needs—and also lessons learned and applied.