Several stories have surfaced in the past few days, making reference to a report by a couple of LSU researchers on the lack of sediment in the Mississippi River since hundreds of dams were installed along the Mississippi River watershed.
Here are links to articles about the report:
LACoastPost.com
Picayune article
Advocate article
The bottom line of the report is that we, as a society, have made decisions about how to use our resources, in this case the water in the river and its associated sediment, that have profound consequences in other places than the ones where those decisions were initially made. The effect is sometimes referred to as the “law of unintended consequences.”
A similar situation exists in the Atchafalaya Basin. The Basin is not without its issues with sediment and the problem that i am referring to is related to sediment, but that is not the central problem.
The “problem” is the deep, wide, ditch that was dug through the middle of the Basin in the 20th century to protect the lower Mississippi River cities from flooding. It is not a problem if your goal is to make the Atchafalaya River an efficient carrier of large amounts of water during a large flood. It is not a problem if your goal is to minimize maintenance needs for that channel. And it is not a problem if you want a wide, deep transportation channel to allow large boats to move up and down the River.
But that successful channel construction and its subsequent “self-scouring” process, which has made it wider and deeper each year, is the cause of most of our problems with poor water flow through the productive swamps and bayous of the lower Basin. In order to create the successful channel, it was necessary to close off many of the smaller streams that fed water into the swamps. And as water levels increased because of levee building, it was necessary to close other streams to prevent rapid siltation of the areas that had previously been watered by over-bank flooding.
My point here is that because of the conscious decision to use the Basin as a floodway, we may have removed much of the resources that we need to correct for the water quality and access problems that we are attempting to address. One unintended consequence of preventing flooding was the acceleration of the changes from marsh to swamp to bottom-land hardwoods. Another consequence may have been an interruption of the natural dynamic processes which then allowed opportunistic or invasive species to change the landscape in unexpected ways.
If the flood control decisions are, in fact, preventing us from correcting the water quality and habitat quality issues in the Basin, then the first step in the recovery process is to face that fact and to honestly discuss how much we are willing to modify the flood control regimen in order to rejuvenate all or part of the swamp ecosystem. Failure to address that issue head-on will result in more wasted time trying to perform piecemeal modifications in hydrology that are not adequate in scope to significantly affect the problems of the Basin.
I have heard that there is a push in Congress to re-visit the 70/30 split of water through the Mississippi and the Atchafalaya. Perhaps such a review could be the beginning of that honest discussion of approaches to the combined problems of flood control, transportation and ecosystem restoration. We can hope; but even if it is not, we in Louisiana need to begin that discussion and stop ignoring the elephant in the room. We may decide to work around the limitations imposed on us and to keep trying small fixes, but we should, at least, recognize those limitations and plan accordingly. With enough honest examination, we might find some areas of compromise.
Make your input known to the deciders.
crc/30