A brilliant string of explosions rippled across a two-mile length of the Mississippi River levee at Birds Point, Missouri at 10pm last night. As the levee disintegrated, a 4-story high cascade of muddy brown water from the Father of Waters gushed into the crevasse, thundering with the flow of eight Niagara Falls. The waters quickly spread out over 133,000 acres of rich farmland, rushing southwards along the 35-mile long Birds Point-New Madrid Spillway. The levee that was destroyed–called a plug fuse levee–was designed to be destroyed in the event of a record flood. In a marathon 20-hour operation, 150 engineers from the Army Corps of Engineers packed 22 wells in the levee with explosives on Sunday and Monday. A raging thunderstorm with dangerous lightning halted the work for a time on Sunday night, as the engineers were pulled off the levee due to concerns about lightning. Final approval for the demolition occurred after a series of failed court challenges, brought by the Attorney General of Missouri, ended at the Supreme Court on Monday. Damage to the farmland and structures along the the Birds Point-New Madrid Spillway is estimated to cost $300 million. The fact that the Army Corps is intentionally causing 1/3 of billion dollars in damage is stark evidence of just how serious this flood is. The Birds Point levee has been demolished only once before, during the 1937 flood.
Figure 1. Still frame from an Army Corps of Engineers Youtube video of last night’s demolition of the Birds Point levee on the Mississippi River.

Figure 2. The gauge on the Ohio River at Cairo was at record highs over the past few days, but the river level is now falling, thanks to the demolition of the Birds Point levee.

Unprecedented flooding on the Ohio and Mississippi Rivers
Snow melt from this winter’s record snow pack across the Upper Mississippi River has formed a pulse of flood waters that is moving downstream on the Mississippi. This pulse of flood waters passed St. Louis on Saturday, where the river is now falling. The snow melt pulse arrived on Monday at Thebes, Illinois, about 20 miles upstream from the Mississippi/Ohio River junction at Cairo. The Mississippi River crested yesterday at Thebes at 45.52′, which beats 1993 as the 2nd highest Mississippi River flood of all-time at Thebes. This floodwater pulse is headed south to Cairo, Illinois, and will join with the record water flow coming out of the Ohio River to create the highest flood heights ever recorded on a long stretch of the Mississippi, according to the latest forecasts from the National Weather Service. Along a 400-mile stretch of the Mississippi, from Cairo to Natchez, Mississippi the Mississippi is expected to experience the highest flood heights since records began over a century ago at 5 of the 10 gauges on the river. The records are predicted to begin to fall on May 1 at New Madrid, end progress downstream to Natchez by May 15. Areas that are not protected by levees can expect extensive damage from the flooding.

The Mississippi River at New Madrid, MO, about 40 miles downstream of the confluence of the Mississippi and Ohio Rivers, crested at 46.54′ this morning, the 2nd highest flood in history. The river is now falling, thanks to the blowing of the Birds Point levee, but is predicted to rise to 50 feet late this week, two feet above the all-time record height of 48 feet. The NWS warns that at this height, “Large amounts of property damage can be expected. Evacuation of many homes and businesses becomes necessary.” Previous record heights at this location:

(1) 48.00 ft on 02/03/1937
(2) 46+ ft on 05/03/2011
(2) 44.60 ft on 04/09/1913
(3) 43.60 ft on 04/04/1975
(4) 43.50 ft on 02/16/1950
(5) 42.94 ft on 03/17/1997

Figure 3. Flooding on the Mississippi in Missouri at the end of April. Image credit: USACE.

The “Project Flood”
The levees on the Lower Mississippi River are meant to withstand a “Project Flood”–the type of flood the Army Corps of Engineers believes is the maximum flood that could occur on the river, equivalent to a 1-in-500 year flood. The Project Flood was conceived in the wake of the greatest natural disaster in American history, the great 1927 Mississippi River flood. Since the great 1927 flood, there has never been a Project Flood on the Lower Mississippi, downstream from the confluence with the Ohio River (there was a 500-year flood on the Upper Mississippi in 1993, though.) On Sunday, Major General Michael Walsh of the Army Corps of Engineers, President of the organization entrusted to make flood control decisions on the Mississippi, stated: “The Project Flood is upon us. This is the flood that engineers envisioned following the 1927 flood. It is testing the system like never before.”

At Cairo, the project flood is estimated at 2.36 million cubic feet per second (cfs). The current prediction for the flow rate at New Madrid, the Mississippi River gauge just downstream from Cairo, is 1.89 million cfs on May 7, so this flood is not expected to be a 1-in-500 year Project Flood. In theory, the levee system is designed to withstand this flood. But the Army Corps is in for the flood fight of its life, and it will be a long a difficult few weeks.

Jeff Masters