USA: Mississippi River Dredging Ensures Navigation

The Vicksburg District of the U.S. Army Corps of Engineers is working to beat Mother Nature and keep low water levels from closing commercial navigation on the rivers in its 68,000 square mile area of responsibility.

According to the National Weather Service this year’s drought is affecting nearly 61% of the country and is causing problems for commercial traffic on the Mississippi River and its tributaries.

One of the primary missions of the Vicksburg District is to maintain a 9-foot deep channel that is 300-feet wide in the Mississippi River and a 9-foot deep channel in the ports to allow commercial traffic to flow. Over the years the Corps has worked to improve the efficiency of the Mississippi River to keep it and its tributaries open to commercial traffic. Thanks to dredging and channel improvements, the Corps has ensured that commercial traffic is able to move up and down the river to support the national and local economies. Channel improvements and dredging by the Corps along the entire length of the Mississippi River provide an annual benefit of over $1.46 billion dollars and $35.5 million dollars, respectively. Over 500 million tons of cargo is shipped on the river each year with a transportation savings of $2.3 billion dollars while supporting 2.7 million jobs. Last year the seven ports in the Vicksburg District area of responsibility shipped over 9 million tons of commercial goods.

As part of its efforts to keep navigation open the Vicksburg District is operating four dredges. This includes the Corps’ Dredge Jadwin and three other contracted dredges. This unusually high amount of dredging is necessary due to the large quantity of silt that was deposited on the harbor and river beds during the historic flood of 2011 and has subsequently affected channel depths. The funding for the dredging was provided by the Disaster Appropriations Relief Act of 2012 as part of the effort to restore and repair the Mississippi River and Tributaries (MR&T) system following last year’s flood. The additional funds have proven essential in the Corps’ efforts to keeping the MR&T system open to commercial traffic despite the silt deposits left from last year’s flood and this year’s low water conditions resulting from the drought. The Vicksburg District received an additional $20.5 million for dredging operations and $77 million dollars for channel improvements and stabilization from the Disaster Appropriations Relief Act. The additional dredging has proven vital as the District aggressively works to keep the ports and rivers in its area of responsibility open to commercial navigation as long as possible despite the low water levels. Unfortunately, unless drought conditions subside and an adequate amount of rain occurs to raise water levels in the river the District’s efforts will be overcome by the lack of rainfall.

During the historic flood of 2011 the river gauge at Vicksburg, MS, reached 57.1-feet with a flow of 2.31 million cubic feet per second (CFS) passing under the bridge. On 12 July of this year the gauge was at 4.9-feet with a flow of 247,000 CFS. The last severe drought to hit the region was in 1988 when the gauge dipped as low as 1.6-feet below zero with a flow of 138,000 CFS. The record low occurred on 3 February, 1940, whenthe gauge was at negative 7-feet with a flow of 108,000 CFS, but that is unlikely to occur again due to the work of the Corps to improve the efficiency of the river.

The Mississippi River flows over 2,300 miles from its source at tiny Lake Itasca in northwest Minnesota to the Gulf of Mexico. Over the course of its journey the Mississippi River Drainage basin impacts 41% of the United States and includes 1.25 million square miles, more than 250 tributaries, 31 states and 2 Canadian provinces. The efforts of the Vicksburg District, along with that of the other five districts within the Mississippi Valley Division, ensure the third largest watershed in world continues to support our great nation.

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Dredging Today Staff, July 23, 2012; Image: usace