The Flood Last Time: Almost Apocalypse

Floodwaters (right) overflow the flank of the Old River Control Structure (left foreground) during the flood of 1973.

The Mississippi flood of 1973, which is about to be eclipsed in size and duration, came within a hair’s width of changing the history of America by changing the course of the lower Mississippi River. To understand the threat posed by the gathering flood of 2011, we need to know what happened, and what almost happened, nearly 40 years ago at the Old River Control Structure. 

As The Daily Impact has been reporting, almost exclusively (see “Mississippi Rising: Apocalypse Now?” and “Mississippi Rising: Update”), the rising waters of the Mississippi pose an existential threat to the Port of New Orleans and, thus, a large chunk of the economy of the United States. To restate, briefly: the river has been trying for a century to change its lower course, as it had previously done periodically, and was shifting its flow toward the Atchafalaya River, which would take it into the Gulf of Mexico at Morgan City, 65 miles west of New Orleans. In the 1950s, seeing the economic disaster that would be precipitated by this change, the Congress ordered the US Army Corps of Engineers to prevent it.

The Corps built the Old River Control Structure — a huge set of flood gates — on a channel connecting the two rivers to enforce the Congressional mandate that no more than 30% of the Mississippi’s flow would be permitted to enter the Atchafalaya. The war against nature — that is what the Corps called it — was in the “mission accomplished” category for ten years after its construction, that is, until 1973. (More detailed history here.)

That year, the Mississippi recorded a flood stage of 58.2 feet (at Red River Landing just downstream from the Old River Structure). The water cut through the flanks of the structure and undercut its foundation pilings, taking it to the very brink of catastrophic failure. The Corps later reinforced and added to the Structure (that is why it is now, officially, called Old River Control Structures, plural) and assures us that the Mississippi will not change course as long as they are on duty.

As a result of that close call, the late Rafael G. Kazman, along with David B. Johnson, of Louisiana State University studied what would happen if the river does change course. Among their findings (excerpted on the website of America’s Wetland Foundation):

• Morgan City would have to be relocated, as would other communities and many businesses, possibly including the massive infrastructure of the offshore oil and gas industry. Fisheries would be altered measurably all across the delta. Oyster reefs would be immediately destroyed, and would take several years to reestablish and become productive (no erysters!). It would probably take two decades to adapt to the new environment around present day Morgan City. Additionally, pipelines, bridges, and the like that cross the Atchafalaya would be destroyed or rendered unsafe.
• New Orleans, possibly Baton Rouge, and all other cities and towns along the lower Mississippi would no longer be able to get their drinking water from the river. It would become too salty, since the lower fresh water flow would not offset the tidal movement of the Gulf. Can you imagine the cost of piping or trucking enough drinking (and flushing, etc.) water from north of Lake Pontchartrain to supply the needs of Greater New Orleans? Can you imagine Greater New Orleans without water for drinking and sanitation? Even when the water was just barely increasing in salinity, there would be severe damage to water heaters, fire sprinklers, fire truck pumping systems, and more.
• One can also imagine the impact on the nation. Massive use of Federal dollars to protect and restore Louisiana’s infrastructure. Loss of natural gas (there would be brown-outs throughout the eastern seaboard). Commerce would be interrupted by restriction of travel and Louisiana=s inability to focus on supplying items traditionally demanded from her natural resources by the nation. Prices of all Louisiana products (from the natural resources [fisheries, oil, gas] to industrial products [poly vinyl chloride, polyethelene, etc.]) would soar. The interruption of the pogie fisheries would be very negative for such food industries as chicken, catfish, and hogs (see the last section of the notes). New Orleans is one of the most important ports in the nation, and it would suddenly cease to function; all shipping and related industries on the Mississippi River would stop. International trade would be further imbalanced. The massive fertilizer business would shut down and the agriculture industry would falter.

In sum, Katzman and Johnson concluded in 1980, “in the long run the Atchafalaya will become the principal distributary of the Mississippi River and that the current main stem will become an estuary of the Gulf of Mexico…the final outcome is simply a matter of time.”

The question of whether that time is now will be answered in the next 10 days or so.

[For updates on this and other stories, check out the Editor’s Log.]