Environment
 

Sediment diversions not the way to rebuild Louisiana’s coast

Without a doubt, the coast of Louisiana is disappearing at an alarming rate. Something has to be done — and quickly — to stop our shorelines from sinking into the Gulf. But are diversions the answer? More and more scientists are now looking at the Mississippi River not as a solution, but as part of the problem.

Why are some of the highest erosion rates occurring where the river has the most influence on the marsh?

The State’s Coastal Protection and Restoration Authority claims it used the best science available in forming its 2012 Master Plan, but some science was ignored and is still being ignored. The authority’s plan features what it calls “sediment” diversions. These are controlled levee breaches that will introduce massive amounts of nutrient-rich freshwater into brackish marsh areas — four on the East Bank and four on the West Bank, two of which will have the capacity of 250,000 cubic feet of muddy water per second. (To put that into perspective, 250,000 cubic feet of water pass through the Bonnet Carré Spillway when the river is at flood stage and the spillway is fully opened into Lake Pontchartrain.)

Garret Graves, head of the coastal authority, often says, “We have to reconnect the river to the land because that is how the delta was formed.” Yes, but it took a millennium for the Mississippi River to build its delta, and we don’t have a thousand years. Moreover, the Mississippi is now a very different river than it was even a century ago. For one thing, it carries only a quarter of the sediment. For another, it’s loaded with chemicals, fertilizers, and pollutants, making it far less friendly to the environment.

For purposes of discussion, let’s focus on just one of the diversion projects, the proposed diversion at Braithwaite, near the St. Bernard/Plaquemines parish line.

A freshwater diversion has been operating in the area since 1992: the Caernarvon Diversion, with a capacity of 8,000 cubic feet per second. According to the coastal authority, it was not meant to be a “sediment” diversion; it was designed to deliver 8,000 cubic feet per second of river water into a brackish water marsh. And, for 17 years, at peak river levels, that’s what it did.

Then, on August 29, 2005, Hurricane Katrina drove a 27-foot storm surge ashore. Overnight, 42 square miles of marshland were gone! Astoundingly, 37 of those 42 square miles were near the Caernarvon Diversion. Add in additional losses from Hurricane Gustav, three years after Katrina, and the total is stunning, the equivalent of a rectangle 14 miles by 17 miles. That’s the distance from the middle of Lake Pontchartrain to the Huey Long Bridge on one side, and on the other from Louis Armstrong New Orleans International Airport to the Lower 9th Ward.

Throngs of scientists from various universities have studied this phenomenon. The key question: Why was the erosion rate near the diversion the highest ever recorded?

What they found was that the high levels of nitrates and fertilizers in the diverted water had transformed the stronger, brackish water vegetation into freshwater vegetation with shallow root systems. Instead of providing the much-touted buffer against storm surge, the whole marsh was peeled up like a carpet!

Here’s the bad news as summarized by the National Academy of Sciences in their study, “Hurricane-induced failure of low-salinity wetlands“:

The dramatic difference in resiliency of fresh versus more saline marshes suggests that the introduction of freshwater to marshes as part of restoration efforts may therefore weaken existing wetlands rendering them vulnerable to hurricanes.

We should not be surprised by the ill effects of river-borne nitrates. After all, they’re the same culprits that cause the “dead zone” in the Gulf of Mexico every summer, a 7,000 square-mile swath of water so depleted of oxygen that marine life can’t survive in it.

The area outlined in red experienced the most serious erosion in hurricanes Katrina and Gustav, in red outline. The red shaded area shows how that area compares to the New Orleans metro area.

Yee Lau and Pat Fitzpatrick

The area outlined in red experienced the most serious erosion in hurricanes Katrina and Gustav, in red outline. The red shaded area shows how that area compares to the New Orleans metro area.

The Coastal Protection and Restoration Authority argues that some of the studies showing that fertilizer pollution weakens marsh and waterway embankments were done on the East Coast, an area with wider — nine foot — tidal ranges. Well, we may not have nine-foot tides, but that the same phenomenon has happened in our area is undisputed fact. Satellite images of the area near Caernarvon show that during Katrina it sustained erosion rates 10 times greater than the higher-salinity Biloxi Marsh — and Hurricane Gustav offered further evidence of the Caernarvon area’s vulnerability to erosion. (For related research, click here.)

The Breton Sound estuary, directly in the path of the Braithwaite and Caernarvon diversions, is one of the most important estuaries in the United States. It is classified by the U.S. Fish and Wildlife Service as an “essential fish habitat.” And yet the planned diversion will transform the marsh into a freshwater environment, driving out the juvenile stages of all saltwater finfish species for the simple reason that they need salinity to survive. A $3 billion-a-year commercial and recreational fishing industry will be threatened. So too, the shrimp and oyster harvests.

Yes, these diversions will cause an enormous disruption to the lives and livelihoods of families who have fished, trawled, and dredged these areas for generations. Add in what we’re beginning to learn about the marsh-destroying power of nitrates and chemicals, and it’s harder and harder to think of the Mississippi River as a “friend” to those of us striving to save Louisiana’s coast.

Captain George Ricks owns and operates Get-Away Fishing Charters and is the president of the Save Louisiana Coalition.

Help us report this story     Report an error    
The Lens' donors and partners may be mentioned or have a stake in the stories we cover.
  • COMMON SENSE

    You spoke the truth Captain George! I loved it!
    Ken R.

  • Len Bahr, Ph.D.

    Mr. Ricks’ opposition to river sediment diversions are hysterical, self serving and replete with errors, exaggerations and misstatements. He admits that without action the coast is toast but he offers no alternative to the controlled release of massive volumes of river water and sediment during exceptionally high river stages – guided by state of the art hydrodynamic modeling.
    If Mr. Ricks and his anti-science colleagues were successful in blocking the keystone sediment diversion projects listed in the state’s coastal master plan, the Plaquemines Parish peninsula will continue to sink beneath the Gulf and everyone loses.

  • Len Bahr, Ph.D.

    Mr. Ricks’ opposition to river sediment diversions is based on
    hysterical, self-serving, exaggerations and misstatements. He admits that
    without action the coast is toast but he offers no alternative to the
    controlled release of massive volumes of river water and sediment during
    exceptionally high river stages – guided by state of the art hydrodynamic
    modeling.

    If Mr. Ricks and his anti-science colleagues were successful in blocking the keystone sediment
    diversion projects listed in the state’s coastal master plan, the Plaquemines
    Parish peninsula will continue to sink beneath the Gulf and everyone
    loses.

  • COMMON SENSE

    The State Master Plan freshwater diversions which are being designed by LACPRA funded questionable “best scientist” such as TWIG and the national non profit environmentalist. The LACPRA assessments are hysterical, self serving and replete with error, exaggerations, and misinformation. Groups such as the Sierra Club and the Audubon Society delayed many barrier island restoration projects which could have been completed many years ago using hard material. These groups stated that ” birds can’t build nest on rocks”, well the birds now have to build their nest in open water. If the first beaks on Shell Island were fixed in a timely manner, 25 square miles of marsh platform could have been saved in the Bastian Bay area. I love science that is free to perform without any political influence and pressure. The present design of the Myrtle Grove Diversion has not yet been completed. In my opinion moving a scenario which the LACPRA states is not survivable in the Birds Foot Delta upriver is very very flimsy to say the lease. Even an experienced fisherman can figure that one out.

    COMEON MANNN!!

  • Capt. George Ricks

    In response to Mr. Bahr. If you read my article correctly, there were links provided to scientific studies that concur with my statements. My colleagues and I are not anti-science, but how about your colleagues use ALL the science, not just the science that agrees with their agendas.
    Capt. George Ricks

  • Mulletman

    Len Bahr’s quote from the 2009 Diversion Summit-
    “The third point and this is what I am suppose to be talking about, river management and hypoxia. I have represented the state for 10 or 12 years, I guess about 10 years on the National Hypoxia Task force, since I have retired at the end of September, that position has not bee filled. I would argue that Louisiana is the most vulnerable state to the Gulf hypoxia. I was really heartened to hear General Walsh talk about, mention hypoxia. The Core, in my opinion, has never paid enough attention to the problem. And that is something that may be changing.
    It is absolutely critical that we realize that solving hypoxia is inexplicably linked to river diversions and restoration. And I am a huge proponent of diversions, I mean, my God. But I am also going to tell you that if, Don Bosh [Phonetic 05:16] here for example, he would be saying, “Well, you know, you have to be careful about these big diversions until we reduce nutrients in the river.” And I think the water shed approach that the Corp is advocating now, to me from a political standpoint, means forming partners upstream, the mid-west states where the nitrogen is burning off the cornfields. We have all got things in common. The Port of New Orleans and the agriculture, everybody is connected or should be connected in the conversation in hypoxia reduction.”

    However, when Captain George Ricks makes a statement against diversions due to
    fertilizer- he is labeled as errors, exaggerations and misstatements.

    The epitome of hypocrisy.

  • crabioscar

    The title of this piece suggested that George Ricks was going to evaluate some other way to rebuild the coast, but I don’t see anything like that in what he’s written. Len Bahr might have started with his claws a little too far out here, but he’s totally right on this point: If you’re going to write this article you need to elaborate on an alternative plan, and let us know why you think it would work better.

  • Feel free to go to http://rodnreelwp.com/the-save-louisiana-colation-plan/ and read the SLC plan.

    Many thanks for the question,

    Mike Lane
    RodnReel.com
    (504) 858-0484

  • KR1964

    Mike, if anyone goes and reads the SLC plan and disagrees with your cartoon-like science will they face a ban on that site, just like you do on rodnreel. Or better yet, will you threaten them and cusre at them like you do at the public meetings., Or even better, will you just post false but defamatory comments about them regarding public corruption.
    You know your arguments against diversion would maybe, just maybe, seem a little more realistic if you argued facts rather than fabricated lies, laced with threats and foul language. But of course, if you argued facts, you would be in favor of the master plan.