• The Mississippi: A Visual Biography by Quinta Scott

    "Great book and great blog - thanks for the first book I have seen that addresses the contemporary river, headwaters to gulf." Dan McGuiness, Audubon, St. Paul, Minnesota

    Click to order

  • Catagories

  • Archives

  • June 2019
    M T W T F S S
    « Oct    
     12
    3456789
    10111213141516
    17181920212223
    24252627282930
  • Meta

  • Advertisements

The Flood of 2011 and the Atchafalaya Delta

“Artificial levees, extending clear to the Gulf of Mexico, may have made human habitation of the delta south of Cape Girardeau possible, but prevented the Mississippi from refreshing its marshes with its sediment when it did flood. Revetments built of concrete mats may have stabilized the navigation channel, but reduced erosion of the banks, a source of sediment in the marshes. James Eads’ jetties at the mouth of the river may have allowed the river to cut a thirty-foot navigation channel through the sandbar blocking the South Pass of the modern delta, but delivered sediment carried by the river to very deep water at the continental shelf, where it washed away, never to be used for marsh building. Closure of the old distributaries of the river may have prevented flooding in the bayou country of Louisiana, but cut the flow of Mississippi sediment to the coastal marshes. Channel dams may have made navigation on the Upper Mississippi profitable, but they retained its sediment north of Alton, Illinois. Dams on the Missouri, from which the Mississippi drew sixty percent of its sediment, did the same. In short at the beginning of the twenty-first century, the coastal marshes south of New Orleans received eighty percent less sediment than they had at the beginning of the twentieth and eroded away.”

I haven’t counted the number of posts I have begun with this quote from The Mississippiand I am doing so again.

Morganza Floodway Structure

Twice, 1973 and 2011, since it was constructed after the Flood of 1927, we have opened the Morganza Floodway Structure to release flood water from the Mississippi into the Atchafalaya River and Floodway. After the Flood of 1973, geologists noted that the Atchafalaya River was building land at its mouth, using all that mud funneled down the Mississippi from erosion from the Midwest and the South.

With this in mind geologists from the University of Pennsylvania–joined by others from the University of Mississippi, Louisiana State University, and the U.S. Geological Survey–began studying the sediment plumes that spewed out of the Mississippi, the Atchafalaya River and Wax Lake Outlet, and through the Bonnet Carre Spillway into Lake Pontchartrain during the Flood of 2011.

Sediment Plumes from the Atchafalaya, Mississippi, and Bonnet Carre

Atchafalaya Delta, 2009

The Atchafalaya slowly spread a wide plume of sediment in to Atchafalaya Bay, where it is building land. The Mississippi, which is too long and too flat and is hemmed between levees, is shooting its mud over the edge of the continental shelf, where it is useless for landbuilding.

Wax Lake Outlet Delta

Similarly, the Wax Lake Outlet, an artificial outlet from the Atchafalaya Basin, built to reduce flooding in the basin, is building its delta.

What is happening in Atchafalaya Bay is what happened naturally before we reengineered the Mississippi for flood control and navigation. Now that we have done it, we have to live with the consequences and find ways to restore Louisiana’s coastal wetlands by mimicking the river’s ways. The Atchafalaya is an example. So is the Mardi Gras diversion at Bohemia, which opened up into Breton Sound this spring during Mardi Gras.

The Mississippi Ridge at Bohemia south of the end of the main line levee

The question about the Mardi Gras Diversion is whether we are going to keep it or dam it. It is an example of what is being done on a small scale and can be done on a large scale along the Mississippi south of New Orleans.

Advertisements

Mardi Gras Pass: Keep it or Dam It

Mississippi River Ridge at Bohemia

While folks partied in the streets of New Orleans on Fat Tuesday, the Mississippi River gave the State of Louisiana a gift, a freebie. The river broke through the low ridge at Bohemia, south of the end of the Main Line levee, and began pouring sediment into Breton Sound to the east. The river is doing for free what the state would have the Federal Government pay $50 billion over 50 years to rebuild barrier island and to divert the Mississippi to Breton Sound on the east and the Barataria Basin on the west. State engineers already had a plan on the books to create a similar diversion into Breton Sound a mere mile from the Bohemia siphon, where the breach occurred.

Bohemia Siphon along the Mississippi

The site of the breech was the old, inoperable siphon, designed to deliver fresh water from the river to the wetlands in the sound. The siphon opens onto a spillway, created in 1924 as a means of relieving flooding in New Orleans. However, this spillway is 45 miles south of New Orleans. After the Flood of 1927 the Bonne Carre Spillway and the Achafalaya and Morganza Spillways were design to siphon water from a flood Mississippi before it reached New Orleans.

Sites of Bohemia Siphon and the Oil Facility on the End of the Road on the Mississippi Ridge

Now the U.S. Army Corps of Engineers has given Houston-based Eland/Sundown Energy permission to seal the crevasse, dam it in order to rebuild the road to their work facility not more than two or three miles down the road, where it ends at a gate to its yard.

Right now the Mississippi is low, very low and the spillway is delivery fresh water and sediment at a much slower rate than the 50,000 cubic feet per second the state-designed spillway would flow. But water and sediment is flowing to Breton Sound. It is a gift from the Flood of 2011. The river will rise again, flood, and spill more water through the breach, enlarging it and sending more water and sediment to the Bohemia Wildlife Management Area and Breton Sound.

Breton Sound at the Bohemia State Wildlife Management Area just off Pointe a la Hache

In 2005 Katrina roared across the Mississippi south of the siphon, and tore north through Breton Sound and Lake Borgne tearing up the wetlands and busting through the levees that protected St. Bernard Parish, trashing the towns there. Then it tore across the wetlands that protects that lovely string of towns on the the State of  Mississippi coast–Bay St. Louis, Pass Christian, Gulf Port, and Biloxi–and destroyed them. Had those wetlands in Breton Sound been in tact, Katrina would not have been as devastating. Never mind what happened after it arrived in Lake Pontchartrain, washed into the canals that drain every drop of water that falls on New Orleans, and collapsed the levees that contained them, flooding the city.

  •  (quintascott.wordpress.com)

The Economic Value of Louisiana’s Coastal Wetlands

Crab Boat on Bayou Penchant in the Western Terrebonne Basin

Rep. Rodney Frelinghuysen, (R-New Jersey) chair of the House Energy and Water Appropriations Committee has released his Energy and Water Appropriations Bill for 2013. This bill covers appropriations for the Department of Energy (Nuclear Security, Gasoline prices, Energy programs, Yucca Mountain, Science Research, Environmental Management) the Corps of Engineers, and the Bureau of Reclamation.

The New Orleans Picayune took note of the fact that Mr. Frelinghuysen’s bill, which includes $4.8 billion for the Corps of Engineers) included no money for Coastal Restoration. He wants to see the Corps of Engineers focus on navigation and flood control projects to the exclusion of environmental projects, including those requested in President Obama’s budget. He notes that such projects are “job creators.” President Obama had proposed $4.7 billion for the Corps budget for 2013, including $16.8 million for ecosystem restoration in Louisiana.

So, what is the value of Louisiana’s coastal wetlands?

From The Mississippi

“Before Katrina and Rita (seven years ago) tore through Louisiana’s coastal marshes, the environmental and economic necessity of a healthy system of wetlands was little understood outside the state. After Katrina and Rita we finally understood that Louisiana’s coastal wetlands buffer storms. But, we still needed to learn that they absorb nutrients, sediment, and contaminants. They serve as the breeding, spawning, feeding, and nursery grounds for fish and shellfish at some time in their life cycles. Summer flounder, spotted seatrout, snook, tarpon, and others spawn in the Gulf, migrate to their freshwater nurseries in the summer, and return to the Gulf when temperatures drop in the fall. So do juvenile brown and white shrimp. Migratory birds rest on Louisiana’s barrier islands on their annual migration from Central and South America. Waterfowl, wading birds, and shorebirds colonize its freshwater marshes, attracted by their diverse menu of fish and shellfish, broad-leaved plants, tall grasses, and shrubs. The marshes provide habitat for the endangered brown pelican and seventy pairs of bald eagles. Furbears–nutria, muskrat, mink, raccoon, otter, bobcat, beaver, coyote, and opossum–thrive in the marshlands. The American alligator–once endangered, now abundant–nests along the banks of coastal freshwater marshes.

“Louisiana’s commercial fishermen harvest 1.1 billion pounds of fish and shellfish including shrimp, crabs, crayfish, oysters, and finfish, up to twenty percent of the nation’s catch, valued at $2.2 billion a year to Louisiana’s economy. Recreational anglers contribute $944 million. More than forty percent of the nation’s fur harvest comes from Louisiana. Louisiana’s alligator farmers take eggs from the wild, hatch them in captivity, return some to the wild, and harvest the rest, netting $9.3 million in skin and meat.

“Louisiana’s three million acres of coastal wetlands are more productive than many agricultural lands, and they are disappearing at the rate of twenty-five to thirty-five square miles a year. If the loss continues at that rate, commercial and recreational fish would decline by 30%, putting up to 70,000 jobs at risk state-wide. Migratory birds dependent on the marshes might decline, having an impact on the rest of the country, on duck hunters, on bird watchers. Fur trappers would see the loss of a $1.3 million industry. The cost of treating drinking water would rise, along with the cost of salt and other minerals taken from the coast. Alligator meat might once again become a delicacy.”

The Flood of 2011 demonstrated the value of the Mississippi River and Tributaries project in mitigating the severity of a very severe flood. The project was started in the aftermath of the 1927 Flood and is almost complete. It is also as responsible for the  decline of Louisiana’s coastal wetlands as any other factor. Levees extending almost to the mouth of the Mississippi have prevented the river from nourishing the wetland with fresh water and sediment every time it floods. All that water and sediment from last year’s flood was flushed into the Gulf of Mexico, where  it went unused for coastal restoration. But the river and tributaries project is almost finished. The levees are built. The floodways work. The reservoirs on the tributaries that retain floodwater in the uplands until the Mississippi can handle it are done.

The job of the Corps of Engineers in the 21st century should be ecosystem restoration on the Louisiana coast and on the Upper Mississippi, where the work of the 20th century has done so much to destroy wetlands.

Demands on the Atchafalaya River: Rice Farming in the Mermentau Basin of Southwestern Louisiana

Grand Prairie Rice Field, Arkansas

Rice farmers needing water: they need it on Grand Prairie in Arkansas where they are depleting the great Mississippi Aquifer; they need it in Southwestern Louisiana where numerous alterations to the landscape has changed the way freshwater flows through the Mermentau and Calcasieu Basins west of Vermillion Bay.

For the long story about rice farming On Grand Prairie in Arkansas, read The Mississippi. Essentially, rice farmers on Grand Prairie want to tap the White River, which runs along the eastern edge of Grand Prairie, and pump the water through a series of canals and into their rice fields. The pump is under construction at Du Vall’s Bluff along the White River, which could change the way water flows through the White River National Wildlife Refuge.

And like rice farmers on Grand Prairie who want to tap the White River for water for their fields, rice farmers in the Mermentau Basin want to tap the Atchafalaya River, some sixty miles or more away, depending on where you tap the Atchafalaya. It will require a series of pumps and canals to accomplish the task.

Last summer as the Mississippi and Atchafalaya carried the Flood of 2011 to the Gulf of Mexico, the rice farmers in the Mermentau Basin watched in frustration as their rice fields dried up in the Drought of 2011 and salt water intruded into them from the Gulf. Some farmers never even planted a crop.  And because they double crop and breed crawfish in their rice ponds, that source of income was also compromised.

The Mermantau and Calcasieu Basins form the Chenier Plain, which William Darby described to a “T” in 1818:

“The marsh between Vermilion bay and the Lake of Mermentau, has nothing to distinguish it from the other marshes of the country, except in its extent, which is about thirty miles square. This great expanse, though generally covered with grass, is not entirely denuded of trees. Near the sea-coast, a singular appearance attracts the attention. These are ridges, which rise above the common level of the marsh, are dry and solid land, clothed with live oak trees. These ridges appear to have once been the sea-shore, and to have been in succession abandoned by the surf, as others were formed by the same means; they all run in lines parallel to the shore, and are separated by lagoons, ponds or the marsh. It is extremely difficult to reach many of these islands; and as no adequate object presents itself to reward the trouble, they are visited but seldom by man. They are the undisturbed retreat of wild animals, deer, turkies, grouse, and perhaps the bear.”–William Darby, 1818

Sediment, pouring out of the Mississippi and flowing westward on longshore currents, came to rest in the successive ridges that form southern reaches of the Chenier Plain. We have disrupted that process of land building with the changes we have made to the Mississippi. There is less sediment spewing out of the river. What does flow out of the river is deposited in very deep water at the continental shelf, where it is unavailable for land building. We have disrupted the long shore currents with jetties. However, some sediment is flowing out of the Atchafalaya and being deposited on the eastern edge of the Chenier Plain, but not enough.

The Mermentau Basin breaks down into two parts: the northern wet prairie, where rice is grown, and the southern Chenier Plain, where ridges and wetlands alternate across the landscape.

 

Like Grand Prairie the northern reaches of the Mermentau Basin are wet prairie, where the low grade and heavy clay soil are ideal for rice farming, because clay prevents the water in rice fields from seeping into the aquifer below. And like Grand Prairie farmers have tapped the bayous that flow through the region and constructed a system of canals to deliver water to their rice fields. In doing so they have changed the way water flows through the region. 

The Corps of Engineers constructed a series of locks and water control structures on Grand and White Lakes to control water levels, convert them into freshwater reservoirs for rice irrigation, and prevent the intrusion of saltwater into the lakes. Continuing high water levels in the Lakes sub-basin drowned wetlands and shifted in the composition of plants. Where excessive flooding eroded the rims of Grand Lake and White Lake, the marshes behind and below the rims also eroded. Saltwater intruding along navigation canals killed freshwater plants, baring the soil that supported them. Tides washed the soil away, converting marshlands to open water.[i]

Then there is what we have done to the Chenier Plain itself: The construction of Louisiana Highway 82 in 1958 across the top of Pecan Island, through the marshes, and across the top of Grand Chenier Ridge, all in the southern reaches, stopped the natural flow of water from north to south. The system of thirty-two culverts and a dozen bridges, designed to allow drainage through the highway, never adequately replaced the natural drainage in the basin. By the turn of the twenty-first century most of the culverts had silted in or collapsed, turning Highway 82 into a dam across the basin, leaving the Lakes sub-basin to the north subject to constant flooding and the Chenier sub-basin to the south starved for freshwater.

The dredging of the Freshwater Bayou Channel, the Mermentau River-Gulf of Mexico Navigation Channel, and dozens of oil access channels allowed saltwater into the Chenier sub-basin marshes, which disintegrated. The introduction of suspended sediment into the western part of the sub-basin restored some of the marshes, but they were disappearing from the rest of the basin.[ii]

The Atchafalaya River is a distributary of the Mississippi. It carries 30% of the Mississippi all of the Red River to the Gulf of Mexico. It is the Mississippi “wannabe,” and Congress and the Corps of Engineers have worked hard to keep the Atchafalaya from capturing the full flow of the Mississippi. Louisiana’s coastal scientists are looking at the Atchafalaya as a source of fresh water for the declining coastal marches, particularly those in the western Terrebonne basin, where salt water is intruding into freshwater marshes. Already, Atchafalaya water is being directed into the Vermillion Basin, just to the east of the Mermantau Basin. A year ago Mermentau rice farmers watched their rice fields dry up as the Flood of 2011 drained away into the Gulf of Mexico, where it was useless for rice farming. Some of that precious freshwater did make its way into the western Terrebonne marshes, where, for the summer of 2011, it pushed salt water out of the marshes.


[i]             Clark, Darryl, and Mazourek, Joyce, Final Environmental Assessment, Freshwater Introduction south of LA Highway 82 Project (ME-16), Lafayette, Louisiana: U.S. Fish and Wildlife Service,  Marsh 2005, 1, http://lacoast.gov/reports/env/Hwy%2082%20ME-16.pdf.

[ii]             Louisiana Department of Natural Resources, Hydrologic Investigation of the Louisiana Chenier Plain, Prepared for the Louisiana Coastal Wetlands Conservation and Restoration Task Force, October 2002, 15, http://www.lacoast.gov/reports/static/HILCP_2.pdf;

The Mardi Gras Diversion at Bohemia

The Mississippi Ridge at Bohemia south of the end of the main line levee

On February 28, New Orleans partied at Mardi Gras, the Mississippi broke through the Mississippi ridge and created a crevasse at the Bohemia Spillway, a couple of miles south of the end of the Main Line Levee, and began delivering precious fresh water and sediment to Breton Sound, which has experienced extreme losses of marshland.

It’s a gift and we can thank the Flood of 2011 for it. All that stood in the way of the crevasse was a slightly elevated gravel road, which the flood washed away last summer. Below are two captions that I cut from The Mississippi: A Visual Biography.

As you will see below, the crevasse represents a potential savings of $6.4 million, if the Corps of Engineers and the Louisiana DNR were to do the work. What the river did by itself may need tidying up, but that work can be done by the Corps and the DNR.

 

Breton Sound at the Bohemia State Wildlife Management Area just off Pointe a la Hache

Mississippi River Ridge: Pointe a la Hache Relief Outlet

Plaquemines Parish, Louisiana

“It is remarkable, that the banks of the river are much more elevated than the circumjacent country. This is occasioned by a more copious deposition along the margins, than at a distance from them. These are thickly covered with grass, and a vast variety of ligneous plants, which serve to filtrate the waters in their progress to the low grounds and swamps, and to retain the greatest proportion of the alluvious substances. Hence the lands along the banks to a certain depth, generally from four hundred to seven hundred yards are excellent for tillage; while the whole surface in the rear of them, extending to the sea, is alternately covered by lakes and impassable swamps.”–Major Amos Stoddard, 1812[i]

The 2004 Louisiana Coastal Area proposal emphasized diverting freshwater and sediments into Breton Sound. So did Louisiana’s post-Katrina 2007 Comprehensive Master Plan for a Sustainable Coast. So did the Corps of Engineers’ post-Katrina proposal. So did numerous unofficial proposals. At the two-year anniversary of the storm, other diversions south of the Caernarvon structure, actual and planned, directed freshwater into Breton sound.

The White’s Ditch siphon, not far from Caernarvon, diverted small amounts of freshwater into northern Breton Sound. The mainline levee ended at Bohemia, where the river was also free to sluice down the Bohemia spillway, but only when it ran high. Built in 1926, the spillway was non-operational by 2005. The Pointe a la Hache relief outlet ran from Bohemia south to the Ostrica Lock. Here, only the natural levee and a gravel road lay between the Mississippi and the marshes in southern Breton Sound. A young natural levee forest had taken root on the ridge. A flooded Mississippi could spill over the levee and wash into the adjacent marshes, or maybe it couldn’t. The gravel road may have impeded overbank flooding. Further south, near Point Pleasant, the Bohemia diversion structure and spillway could have diverted water into Breton Sound through Bayou Lamoque the same rate as Caernarvon, was inoperable, but was included in Louisiana’s 2007 plan for a sustainable coast. At the beginning of the twenty-first century, how much fresh water the overbank flooding introduced into southern Breton Sound had not been measured, nor had any changes in water quality caused by the flooding.

In 2001 the Corps of Engineers and the Louisiana Department of Natural Resources began design work on a diversion at Fort St. Philip, on the east bank opposite Fort Jackson. The agencies planned to divert water from the river at the rate of 2,500 to 5,000 cubic feet per second into 2,252 acres of deteriorating wetlands and open water near the site of the old fort. The existing marshes graded from fresh at the toe of the ridge to saline. The site, short on development and infrastructure, presented a rare opportunity to rebuild marshes in shallow estuarine waters.

Engineers would cut a series of gaps in the bank of the river, armor them, creating channels that would carry river water and sediment to open water adjacent to the natural ridge of the river. Farther downstream they would create a diversion outfall channel, which would connect to Fort Bayou. Holes punched in the outfall channel would allow water and sediment to leak into the shallows between the bank and the bayou. The bayou would carry water and sediment to the east beyond the reach of the channel. The Corps and the DNR expected to create and 624 acres of marsh over the life of the project, recreate the progression of wetlands from natural levee to emergent marsh to mudflats, and reduce the loss of marsh in the rest of the site. The expected cost was $6.4 million. A final note: The Corps and the DNR suspected that the introduction of freshwater into marshes that were largely saline would disrupt existing oyster leases. And, the siltation the engineers hoped for might plugged oil and gas canals and disrupt access to the project area.

The coastal scientists and engineers who published the Comprehensive Recommendations Supporting the Use of the Multiple Lines of Defense Strategy to Sustain Coastal Louisiana in August 2007 recommended encouraging the Mississippi to wash over its banks, a rates totaling up to 100,000 cubic feet per second, over the twenty miles south of Bohemia. Doing so would rebuild its natural levee. It was a habitat that, in the twenty-first century at least, was unique to Louisiana, where all other ridges were under intense development. The process would offer scientists and engineers an opportunity to observe and understand how a river develops its natural levee.[ii] Photograph 2007

 

Bohemia Siphon along the Mississippi

 

Mississippi River Ridge: Small Siphon at Bohemia

Plaquemines Parish, Louisiana

James Buchanan Eads solved the problem of sandbars blocking the passes at the mouth of the Mississippi with jetties, which opened Southwest Pass to shipping, but as early as 1832 Major Benjamin Buisson, Chief Engineer of the State of Louisiana, proposed and the State Legislature approved dredging a canal to connect the River at Fort St. Philip to Breton Sound. The State sent the proposal to Congress, which ordered a survey in 1837. Major W.H Chase did the survey and presented the War Department with a plan for the canal at an estimated cost of ten million dollars, a price tag that was way beyond Congress’s reach for public improvements in 1837.

Mr. R. Montaigu, a civil engineer, revived the idea twenty years later, but it was not until 1871 that Congress ordered the Corps of Engineers to make surveys and plans for the canal. Major C.W. Howell drew up the plans and a board of army officers, that included Major Howell, made a report that favored the plan over Eads’ proposed jetties in 1873. The cost would be thirteen million dollars. General A.A. Humphreys, Chief of Engineers and Eads’ rival, approved the plan, but General J.G. Bernard dissented, saying the cost estimates for the canal were unreliable, the canal would not solve the problem, would not be finished until 1884, and at least one of the passes in the river should be improved. And, should South Pass be jettied, it would function like a canal.

In February 1874 Eads proposed delivering a channel twenty-eight feet deep and 350 feet wide at a cost of ten million dollars, and he offered to work for free until he had achieved a channel twenty feet deep when he would receive a million dollars and a million for every two feet until the channel reached twenty-eight feet. The rest, five million dollars, would go for maintenance.[iii]

Eads got the job and got the job done. His jetties and those that followed delivered sediment to very deep water, where it was useless for land building. Combine the jetties with the levees and the wetlands in the Barataria Basin to the west and Breton Sound to the east were starved for freshwater and sediment.

In the wake of Katrina the canal was back and Fort Philip, located south of the end of the mainline levee and already the site of a planned diversion, was the proposed site of a major diversion of freshwater and sediment to Breton and Chandeleur Sounds.

First, the diversion: In 1994 Ivor van Heerden proposed diverting Mississippi water and sediment to Breton and Chandeleur sounds through the Bohemia Wildlife Management Area near Fort Philip and creating a new delta. He reiterated the proposal in a 2003 paper and again in his 2006 book, The Storm. The diversion would be huge, 200,000 cubic feet per second, would create more than five thousand acres or eight square miles of wetlands every year, leading to 140 square miles of new land within twenty years. The Bird-foot Delta would be abandoned, though enough water would be left the river to maintain the shipping channel through Southwest Pass. Or, a new navigation channel would be dredged just north of Empire through Adams and Bastian Bays in the Barataria Basin to the Gulf of Mexico. A new lock and other control structures would have to be built to make it possible. The delta would evolve into a series of barrier islands, which would coalesce with the Breton and Chandeleur islands to the east and the Barataria Bay islands to the west, and create a continuous arc of islands from Grand Isle to the northeastern tip of the Chandeleur Islands, a speed bump to hurricane storm surges. The new wetlands would further reduce storm surges. New Orleans’ levees would be protected. Eventually, the new delta would extend across MRGO, leading to its closing, but after Katrina that was on Louisiana’s agenda anyway. The proposal followed van Heerden’s dictum: “Barrier islands protect the wetlands, the wetlands protect the levees, the levees protect the home.” Photograph, 2007

 


[i]      Stoddard, 159.

[ii]             Multiple Lines of Defense Assessment Team, “Comprehensive Recommendations Supporting the Use of the Multiple Lines of Defense Strategy to Sustain Coastal Louisiana,” Lake Pontchartrain Basin Foundation, August 17, 2007, 71-72, http://www.saveourlake.org/pdfs/JL/LPBF%20-%20CRCL%20Final%20Draft%20MLODS%20report%208-17-07%20for%20release%20part1.pdf; Lane, Robert R., John W. Day, Jr., Burnell Thibodeaus, “Water Quality Analysis of a Freshwater Diversion at Caernarvon, Louisiana,” Estuaries, Vol. 22, No. 2A, June 1999, 329, http://estuariesandcoasts.org/cdrom/ESTU1999_22_2A_327_336.pdf; Louisiana Coastal Wetlands Conservation and Restoration Task Force, Delta Building Diversion North of Fort St. Philip (BS-10), October 2003, http://data.lacoast.gov/reports/gpfs/BS-10.pdf.

[iii]             Corthell, Elmer Lawrence, A History of the Jetties at the Mouth of the Mississippi River, New York: John Wiley & Sons, 1881, 17-23; Barry, 68-71;

1 Mississippi, Wild Miles, and the Restore Act

Roseau Cane, Delta National Wildlife Refuge, 2005

Cruise the roseau canyons of the Delta National Wildlife Refugeand enjoy what Louisiana offers right at the edge of the Gulf of Mexico. While protected from the oil that BP poured into the Gulf of Mexico two years ago, the Pass a Loutre Wildlife Management Area, just to the south of the Delta refuge, took the brunt of the oil and parts of it are still closed.

Louisiana Department of Environmental Quality Image of Oil easing into Pass a Loutre Wildlife Management Area

Pass a Loutre and the interior wetlands and barrier islands at the edge of the Gulf of Mexico are Louisiana’s first line of defense against hurricanes, and as we learned in 2010, against gushers of oil.

Timablier Island at the Gulf of Mexico

1 Mississippi, founded in September 2011, is once again urging its members and others to write their Congressional representatives to urge them to vote yes on the Restore Act, to restore the Gulf of Mexico and the Louisiana Coastal Wetlands as well as those in Mississippi, Alabama, and Florida. It’s a tall order, because the deterioration of the Louisiana Coastal Wetlands is becoming critical. Katrina taught us how vulnerable New Orleans has become to massive hurricanes. Restoring the wetlands south of the city would do much to protect it. Click here to urge you representatives to vote yes on the Restore Act.

In addition 1 Mississippi had a recent article on the work of John Ruskey and Mark Clark of the Quapaw Canoe Company in Clarksdale, Mississippi to show us the Wild Mississippi at WildMiles.org. These gentlemen are canoeing the Mississippi from St. Louis south and documenting the wild places along the river and putting their images on their blog, WildMiles.org.

Big Sunflower River at Holly Bluff

Quapaw Canoe first started showing people the beauties of the Big Sunflower River, which heads not far from Clarksdale. Now they are showing us the beauty of the wild lands on the banks of the Middle and Lower Mississippi. And they are not easy to get to. I live on the uplands two or three miles from the Middle Mississippi and without their canoe I have to travel across privately-owned wheat, corn and soybean fields to get to the banks of the river. When I was working on The Mississippi, I found almost impossible to get to the bank of the Lower Mississippi.

Chartre Island Snake

Only Chartre Island is accessible from the mainland and only when the river is down and I can hike the dike across the Chartre Island Side Channel. Once on the island I could find no trail that would take me to the bank of the river.

Chartre Island Side Channel

Not Enough Sediment in Mississippi to Rebuild Louisiana Wetlands

Fragmenting Wetlands in the Barataria Basin at Port Sulphur, Louisiana

Fragmenting Wetlands in the Barataria Basin at Port Sulphur, Louisiana

The dream that we can make enough freshwater diversions from the Mississippi into the Barataria Basin to the west and Breton Sound to the east to reverse land loss is a fantasy.

A pair of geologists at Louisiana State University issued a report last week, noting that we have deprived the Mississippi River of the sediment necessary to counter the raise in sea level and rebuild the Louisiana coast.

The researchers have concluded that the 8,000 dams we have built in the Mississippi Basin are the culprits. Any sediment that may flow out of the uplands into the tributaries gets trapped behind the dams.

Lock and Dam 26, Alton, Illinois

Lock and Dam 26, Alton, Illinois

We built the 26 dams on the Upper Mississippi to turn it into a profitable navigation channel. All the sediment that comes out of the uplands is trapped behind the dams.  The Corps of Engineers must dredge the navigation channel constantly to maintain its 9-foot depth.

There are six on the Missouri, which flows through soft, erodible sedimentary rocks and supplied the Mississippi with 60% of its sediment before the construction of its dams in the 1950s.

Niobrara River, at Niobrara, Nebraska

Niobrara River, at Niobrara, Nebraska

Take the Niobrara River, which flows to the Missouri at Niobrara, Nebraska.  It heads neat Lusk, Wyoming and flows along the northern margin of the soft, erodible Sand Hills in Nebraska, turns north, and empties into the Missouri.

It is a river that somehow has not been dammed or channelized, but it has still been changed by the construction of the Gavins Point Dam downstream from its confluence with the Missouri. The dam turned the Missouri into a lake and raised the level of the Missouri 2.9 meters at the mouth of the Niobrara.

Note: When a fast moving stream meets a still body of water, it deposits its sediment in the still body of water and forms a delta. That’s what the Niobrara does with the sediment eroded from the Sand Hills when it meets the lake-like Missouri. This is the case with other tributaries of the Missouri. It is all retained behind the Missouri River dams.

Missouri River at Niobrara, Nebraska

Missouri River at Niobrara, Nebraska

Before the construction of the dam, the Missouri carried away all that sediment to the Mississippi, which delivered it to a still body of water: the Gulf of Mexico and built the Louisiana coast.

Now what sediment the Mississippi does carry to the Louisiana Coast does not get to it because we have built levees clear to Venice, Louisiana to prevent the river from flooding and depositing its sediment on the coast. Hence, we have to design freshwater diversions to deliver sediment to the wetlands, which are starving for lack of freshwater and sediment. But, now we are finding those won’t work.[1]


[1] Etheridge, F.G., Skelly, R.L., Bristow, C.S., “Avulsion and Crevassing in the sandy, braided Niobrara River complex response to base-belel rise and aggradation,”  In Fluvial Sedimentology by Norman Dwight Smith and John Rogers, found in Google Books http://books.google.com/books?id=7i_pWcmzRZ4C&pg=PA181&lpg=PA181&dq=Niobrara+Missouri+River&source=bl&ots=94teq3rvPZ&sig=_Ua9y4paapkbENbXSDPBU6r6rhQ&hl=en&ei=pS5KSoq_K4f-NZ-c-fIN&sa=X&oi=book_result&ct=result&resnum=6.