You've likely heard lots of "water cooler" chatter about rising water levels along the Mississippi River. Last week, the WAFB Storm Team told you that forecasts for points along the river right here in Louisiana were calling for the Mississippi to reach near-record levels during mid to late May.
On Monday afternoon, the National Weather Service (NWS) and the U.S. Army Corps of Engineers (USACE) upped the ante on those river forecasts, calling for the potential for all-time record river stages at Red River Landing (65.5 ft) and Baton Rouge (47.5 ft) on or about May 21st. Down river at Donaldsonville, the forecast for 36.0 ft would effectively tie the record stage for that location. In addition, the Atchafalaya at Morgan City is projected to rise to 9.5 ft, which would be the second highest stage ever for that site.
For many WAFB viewers, the anticipated rise on the Mississippi River (and the Atchafalaya) is little more than a curiosity, but for business interests "between the levees" -- and for some neighborhoods lying adjacent to the levees -- this in no trivial matter. River traffic likely will be curtailed by the swift, high water: reduced numbers of barges per tow, requirements for greater horsepower and/or assisting tugboats to move larger barge flotillas, and the possibility of one-way traffic -- all adding to the costs of operation and delivery of goods.
At the same time, on the "dry" side of the levees, some areas aren't quite so dry, as sand boils and seepage become increasing problems. And the situation at Angola State Penitentiary is more serious: the prison's levees seem destined to be overtopped in the coming weeks, should the current forecasts prove valid.
Late Monday evening, the USACE purposefully breached a Missouri levee to reduce the flood threat in and around Cairo, IL; plans call for two more "controlled" breaches in that region by mid-morning on Tuesday. While the breaches are expected to reduce water levels by as much as four feet near Cairo and surrounding communities in Illinois, Kentucky and Missouri, preliminary computer model runs by the NWS's Lower Mississippi River Forecast Center (LMRFC) suggest that there would be little, if any, significant reduction in water levels here in Louisiana. That's mainly because the breaches only re-direct some of the flood waters, and that these waters eventually find their way back into the Mississippi channel.
Without doubt, anticipating river levels nearly three weeks from now is not an exact science. One clear signal of the uncertainty in this guessing game was the surprising rise for the forecasted crests in Louisiana on Monday: model projections at Red River Landing and at Baton Rouge jumped by three feet or more in between the morning and afternoon computer runs.
Consider this: areas from eastern Oklahoma, through Arkansas and into the mid-Mississippi Valley and the Ohio River basin have seen as much as 10" to more than 20" of rain in the past four weeks, far above normal. Portions of that same area received from 2" to 4" or more just on Monday, with more to come, prompting the run-off models to anticipate big rises along the Mississippi later this month. And it should be noted that the forecast into latter May does not take into account any rain in the drainage basin after the next three to five days. Should the current "wet" weather pattern persist for another week or more, the outlook for ‘Old Man River' here in the Bayou State could become even more grim.
The USACE is taking steps in preparation for the possible opening of the Bonnet Carre' Spillway to relieve water levels along the lower Mississippi as it approaches and passes through the Crescent City. Now many are asking about the possibility of opening the Morganza Spillway, located north of Baton Rouge, to provide some relief closer to home. As of last week, and before this more recent set of ominous forecasts, Colonel Edward Fleming, commander of the New Orleans' District of the Corps, suggested that it was unlikely that there would be a need to use the Morganza Spillway. Since the structure's completion in the mid-1950s, it has been opened only once, in May of 1973. Although the river was high at that time, the decision to open the Morganza Spillway then was not because the water had achieved a critical stage. Rather, the decision was driven by the Corps' need to reduce the stress on the Old River Control Structure, located north of the Spillway.
So, in more than 50 years, the Morganza has never been used for flood control on the Mississippi. And there is good reason for that: opening the Morganza Spillway re-directs a portion of the Mississippi into the Atchafalaya Basin. Many Louisiana residents don't realize that a portion of the Mississippi's flow already is directed down the Atchafalaya. It's a somewhat complicated arrangement, but a series of channels and floodgates (including the Old River Control Structure mentioned above) are used to send 30% of the "total combined flow" of the Red River and the Mississippi down the Atchafalaya, by order of the U.S. Congress. Since the Mississippi dwarfs the Red in terms of volume, the design scheme means directing a portion of the Mississippi (essentially 30%) through the control complex. Quite an engineering feat in reality, but the Corps has been doing it successfully for decades.
Opening the Morganza Spillway would mean increasing the Mississippi's contribution into the Atchafalaya Basin -- and likely overwhelming that basin with too much water. The spillway's path cuts through agricultural sections of western Pointe Coupee Parish (before reaching undeveloped areas of the Atchafalaya) and that's certain to rustle some feathers. But maybe the bigger threat deals with the increased slug of water that would inundate Morgan City. It seems as no coincidence that the flood-of-record on the Atchafalaya at Morgan City (10.5 ft) came in May 1973 -- the one time that the Morganza Spillway was opened! With Morgan City currently forecasted to go to 9.5 feet already, more water is the last thing they need.
So for the time being, we'll sit and watch as Mother Nature, and the Corps of Engineers, potentially make history along the Mississippi.
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