• 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

  • March 2017
    M T W T F S S
    « Oct    
     12345
    6789101112
    13141516171819
    20212223242526
    2728293031  
  • Meta

The St. Johns Bayou-New Madrid Floodway Project

1 Mississippi is hosting a webinar on Monday, June 17 at 2:00 PM CDT on the proposal to close the New Madrid Floodway at its foot. Click here:  https://attendee.gotowebinar.com/register/8363148575022700544 to register for the webinar.

It’s baaaack: The closure of the foot of the New Madrid Floodway is back on the agenda of folks who farm the floodway and see there land flooded every year the Mississippi Floods. If you remember, two years ago the floodway was opened to provide extra storage capacity for the flooded Mississippi. But every time the river floods water backs up into the floodway at its foot.

It seems that Senator Roy Blunt is pressuring the Obama Administration to go forward with the closure of the floodway by putting a hold on President Barack Obama’s nomination of Gina McCarthy as head of the Environmental Protection Agency (EPA).

I cut the following essay from The Mississippi, because the issue had been resolved in 2007 when U.S. District Judge James Robertson of the District of Columbia ordered the project halted and the work already accomplished dismantled. It had not. Soon after the Memphis District of the US Army Corps of Engineers began working to satisfy the court’s objections to the closure of the floodway. However, the U.S. Fish and Wildlife Service and others who object to the project or no more satisfied with it as it stands now than they were when the judge ruled in 2007. These things never go away. This link will help you understand where the project stands now.

The following is the full story as it stood in 2007:

Ten Mile Pond Conservation Area in the New Madrid Floodway

Ten Mile Pond Conservation Area in the New Madrid Floodway

The St. Johns Bayou-New Madrid Floodway Project

In 1928 when General Edgar Jadwin and the Corps of Engineers designed the New Madrid Floodway, the agency left a 1,500-foot gap at the foot of the setback levee for the release of floodwater and installed a fuse plug levee at Birds Point at its head. The designers understood that the lower third would become a backwater storage area. To compensate landowners for the use of their land, the agency purchased flood easements in the upper two-thirds. That wasn’t necessary in the lower third, which would flood with the river every time. It was the floodway’s role as a backwater storage area that created an uproar at the beginning of the twenty-first century, when the Crops published its plan for the St. Johns Bayou-New Madrid Floodway Project, which promised to eliminate backwater flooding in the New Madrid Floodway.

The Water Resources Development Act of 1986 authorized the dredging of St. Johns Bayou for flood control, the St. Johns Bayou Pump Station, which included a gated culvert across the foot of the bayou, and the New Madrid Pump Station and a gated culvert set in the 1,500-gap in the setback levee of the New Madrid Floodway. St. Johns Bayou Basin is located between the setback levee and Sikeston Ridge. The gated culverts would halt backwater flooding from the river, but assure interior flooding in both St. Johns Bayou basin, located between the setback levee and Sikeston River, and in the New Madrid Floodway. The pumps would clear water ponding behind the closed culverts. The culvert across St. Johns Bayou was built. In 1997 the Memphis District of the Corps of Engineers filed its intent to prepare and environmental impact study of the project.

Environmentalists, river conservationists, the Environmental Protection Agency, the U.S. Fish and Wildlife Service, the Missouri Department of Conservation, the Missouri Department of Natural Resources, and taxpayer watchdogs: all objected. They balked at closing the last connection the Mississippi had to its floodplain in Missouri, at the $65 million cost, at the damage that would be done to Big Oak Tree State Park, at the loss of spawning habitat for fishes and wintering places for waterfowl, to the channelizing of St. Johns Bayou and other drainage ditches. They complained that the project would benefit a handful of big landowners. They noted that East Prairie in the St. Johns Bayou Basin would continue to flood due to runoff from roofs and parking lots. They encouraged the Corps to find non-structural solutions to the flooding problems, including a ring levee around East Prairie.

The East Prairie Enterprise Community, the local sponsor of the project, and other residents of Swampeast, weren’t interested in environmentalists’ concerns. East Prairie residents complained that a ring levee would cut them off from the rest of the world. Farmers gave little support to the Wetland Reserve Program. They had rejected a 1993 U.S. Fish and Wildlife Service offer to purchase land in the St. Johns Bayou basin for a national wildlife refuge at fair market value. Nor were they interested in converting their lands from crops to timber.

In September 2000 the Memphis District sought to please both the environmentalists and the residents of Mississippi County when it revised its plan. The floodgate and the pumps would stay, but the following changes would be made: the Corps would dredge only the St. Johns Bayou-St. James Bayou drainage ditch, reduce its width from 200 feet to 120 feet, and excavate only one side to avoid cutting into forests. The engineers would not dredge the upper 3.7 miles of St. James Bayou Ditch to avoid the habitat of the golden topminnow, a state endangered fish; would avoid mussel beds or relocate them and set up a ten-year monitoring program. They would set rock structures in the channels to enhance fish habitat; move water in and out of the lower reaches of the floodway and the basin for winter and early spring waterfowl and to allow spawning fish to pass to and from the river; purchase conservation easements on 765 acres of herbaceous land along the channel to replace shorebird habitat; reforest 9,557 acres of seasonally flooded cropland. At Big Oak Tree State Park they would build a control structure to regulate water in its swamps–enough for the cypress, but not too much for the oaks.

Big Oak Tree State Park

Big Oak Tree State Park

The Corps published essentially the same plan in June 2002, but added the construction of the wildlife corridor between Big Oak Tree Park and the Ten Mile Pond conservation area and riparian buffers along sixty-four miles of streams and drainage channels to filter water flowing to Big Oak Tree. Most important, the engineers made the commitment to the restoration of Big Oak Tree, purchasing and reforesting 1,800 acres surrounding the park and restoring the park’s hydrologic connection to the Mississippi with water control structures in the park, a canal with gated culverts set in the mainline levee to allow water to flow between the park and the river. The cost of the new plan came to $85 million dollars and still did not satisfy the Missouri Department of Natural Resources, the owner of Big Oak Tree Park.

In 2004 the Memphis District issued a contract for the construction of the New Madrid closure and the pump, but stopped work on the project when National Wildlife Federation and the Environmental Defense Fund filed suit in Federal Court, alleging violations of the Clean Water Act.

In December 2005 the Corps published a second Revised Supplemental Environmental Impact that would allow fish to spawn in the sumps behind the culverts and would reestablish the hydrological connection between Big Oak Tree and St. James Bayou through a culvert in the levee.

The Corps pointed out repeatedly that the success of the project depended on finding people willing to sell their land for mitigation to add 1,800 acres to Big Oak Tree State Park or the addition 1037 acres needed for the wildlife corridor and riparian buffers.

In the fall of 2006 the Corps of Engineers started work on the project, even after being told they would likely lose the Federal suit filed two years earlier. The suit came to fruition in September 2007, when U.S. District Judge James Robertson of the District of Columbia ordered the project halted and the work already accomplished dismantled.

Low Water on the Mississippi and Thebes Gap

Thebes Gap:

Alexander County, Illinois

“Here is a vast ledge of rocks, which stretch across the river in a direct line. The best channel in the middle of the river, in which place in low water, there is not more than six feet over the rocks.”–Zadoc Cramer, 1814

Rock Formation in the Middle Mississippi at Thebes Gap, 2006

Rock Formation in the Middle Mississippi at Thebes Gap, 2006

The Mississippi is running very low. After the Flood of 2011, the river drained away very quickly and the rain stopped. By the Summer of 2012, we in the Midwest were well into the Drought of 2012 and the river was showing the effects. Now in January 2013, the Upper Mississippi is frozen and the system of locks and dams is retaining water north of Alton, Illinois. On the Missouri a similar system of dams is retaining water in South Dakota and too little water is flowing into the Mississippi to maintain water levels for the 9-foot navigation channel on the Middle River.

Look at any aerial photograph of the confluence of the Missouri and Mississippi. The muddy Missouri spews a flume of silty water into the relatively clear Mississippi. They flow side by side downstream--the Missouri on the west, the Mississippi on the east--for several miles. During the very cold winter of 2000-2001 it was possible to see this phenomenon from the Illinois bank near the spot where Lewis and Clark started their journey up the Missouri: Lock and Dam 26 at Alton trapped ice coming down the Mississippi. South of the dam the river flowed free of ice, but ice did flow out of the mouth of the Missouri. At the confluence the two rivers, the icy Missouri and the ice-free Mississippi flowed side by side in the Mississippi channel.

Look at any aerial photograph of the confluence of the Missouri and Mississippi. The muddy Missouri spews a flume of silty water into the relatively clear Mississippi. They flow side by side downstream–the Missouri on the west, the Mississippi on the east–for several miles. During the very cold winter of 2000-2001 it was possible to see this phenomenon from the Illinois bank near the spot where Lewis and Clark started their journey up the Missouri: Lock and Dam 26 at Alton trapped ice coming down the Mississippi. South of the dam the river flowed free of ice, but ice did flow out of the mouth of the Missouri. At the confluence the two rivers, the icy Missouri and the ice-free Mississippi flowed side by side in the Mississippi channel. In the Winter of 2013 too little water is spewing out of the Missouri to feed the Middle Mississippi.

 Thebes Gap is the geological break point between the Upper Mississippi and the Lower Mississippi. The Upper Mississippi flows through a rocky gorge from Minneapolis to Thebes Gap. South of there the Lower Mississippi meanders across an alluvial plain.

At the beginning of the glacial age, the Lower Mississippi flowed along the western valley wall through an alluvial floodplain in the Western Lowlands along the Black, White, and St. Francis Rivers.

From The Mississippi: “Geologists have speculated that the river abandoned its alluvial valley and diverted through Thebes Gap, a narrow bedrock canyon in the Benton Hills, through the series of glacial floods at the end of the Wisconsinan age. At the beginning of the twenty-first century, seismologists questioned why the Mississippi would abandon its comfortable alluvial valley to ream a new course through bedrock. They noted that fault lines in the Benton Hills were active 10,000 years ago, and speculated that an earthquake along fault lines in the Benton Hills opened the canyon that is Thebes Gap. Glacial River Warren, which broke out of a glacial lake that covered northern Minnesota and North Dakota and reached north into Canada,  thundered through it, and deposited a classical alluvial fan at the mouth of the canyon.”

 “Thebes at the head of the Grand Chain and Commerce at the foot of it were towns easily rememberable as they had not undergone conspicuous alteration. Nor the Chain, either–in the nature of things; it is a chain of sunken rocks admirably arranged to capture and kill steamboats on bad nights.–Mark Twain, Life on the Mississippi

Thebes Gap, where the Mississippi takes a wide turn into the narrow reach of Thebes Gap.

Thebes Gap, where the Mississippi takes a wide turn into the narrow reach of Thebes Gap.

Mark Twain knew Thebes Gap, and while it is no longer killing steamboats, this winter modern tows can’t get through this narrow gorge between the Upper Mississippi and the Lower Mississippi.

The U.S. Army Corps of Engineers have contracted with Newt Marine and Kokosing, a marine engineering firm out of Iowa and Michigan,  to remove the rocks from Thebes Gap. When they are done there on January 11, they will move on to Grand Tower.

A tow steams passed Tower Rock at the beginning of December.

A tow steams passed Tower Rock at the beginning of December.

The river level today at Chester, Illinois is -0.6 feet, which means it is possible to walk out to Tower Rock and see just how low the Mississippi is.


[i]             Cramer, 173; Harrison, Richard W., “Report on Investigations of the Benton Hills, Scott County, Missouri, in Midwest Friends of the Pliestocene, 42nd Annual Meeting, 19-21 May 1995, 7.3; Harrison, Richard W., “Mid-Continent Urban Corridor Mapping Project,” USGS Project No.: 7160-11, U.S. Geological Survey, http://erp-web.er.usgs.gov/reports/annsum/vol40/cu/harrison.htm; Elfrink, Neil, “Gujarat Analog Response,” Archives of Central U.S. Earthquake Hazard MailList, March 21, 2001, http://clifty.com/hazard/archives/1010302-021954.html; Guccione, Margaret, “Re: ‘Gujarat Analog,’” Archives of Central U.S. Earthquake Hazard MailList, Feb 16, 2001, http://clifty.com/hazard/archives/1010216-111758.html.

Drought, Low Water, the Middle Mississippi, Side Channels, and Fish

The Jefferson Barracks Reach of the Middle Mississippi, July 2012.

Starting in April, I spent the spring and summer working on the third of three articles on the American Bottom in Monroe County, Illinois for Confluence Magazine, published by Lindenwood University. The first, published a year ago, discussed the Hill Prairies and the bluffs that rise above the American Bottoms. The second covered the floodplain between the bluff and the river levees. This summer’s work was for the article on the land between the levees and the river and the side channels that flow between the islands and the east bank.

The side channels provide fish and waterfowl quiet places to breed and rest. Where they are deep, they provide fish with places to wait out the winter, when the river may be frozen, and wait out  a drought, when the channels may dry out. The Drought of 2012 was very hard the side channels and therefore on the fish.

Dead fish, mostly Asian carp, in the Jefferson Barracks Borrow Pit after the Flood of 2011

When I started in April, the coming drought was not really apparent yet. Yes, last year’s monster flood drained away very quickly, leaving fish stranded and dying the the borrow pits on the river side of the levees. But there was still water in the side channels that ran between the east bank and the islands. Occasionally, I would trip over a dead carp, washed up near the bank. The wheat was doing well. So were the baby soybeans.

The young corn looked okay, too, though it would suffer come July and August.

Wherever I came to the bank of the river, there was evidence of last summer’s flood in the dead willows that had been stripped of their leaves during the flood. And there was evidence of the growth of new vegetation. Even with the dry conditions, new growth wasted no time to set started once the soil warmed up.

River Mile 143, June 2012

To make the article work I needed to get to the side channels. Only the Fort Chartres Chute and Island are in public ownership. The rest are in private hands and required permission to get to them. Fortunately, two farmers allowed me on their lands, and one provided transportation to Calico Island. We rolled down the steep bank onto the bank of the side channel.When we arrived the first time, I put my camera to my eye and found the battery had died. I love pixels, but I hate batteries required to make them work. Fortunately, the farmer with the transportation was willing to have a go of it the next day. And it was serendipity, because when we went back, the river had dropped considerably overnight, and we were able to cross the chute, that was too deep the day before, and onto the island.

Still Wet Mud on Calico Island, July 2012.

As the river continued to drop the little inlets you see in the muddy bank above turned into small pools, in which fingerling fish were trapped.

When wer returned to the side channel, we discovered we had run over a catfish, a very large catfish, and rolled it up onto the bank.

Calico Island Catfish

In mid-July Calico Chute still had water in it, but our dead catfish told us it was growing shallower and shallower. Very small fish were trapped in pools that formed here and there in the mud.

A few weeks later I hiked out to the edge of Jefferson Barracks Chute. Its upper reaches were drying out, but the lower half carries Palmer Creek to the river and still held water.

Lower Reach of Jefferson Barracks Chute

I did not get to Chartres Island Chuteuntil late October and found only the plunge pool, downstream of the closing dam at mid-chute, filled with water. When I first hiked out to the chute in 2009, it was filled with water, both upstream and downstream of the closing dam.

Chartre Island Side Channel upstream of closing dam, 2009

This trip the upstream end of the chute was dry. A dense stand of willows, as tall as me, (5’6″) had taken root in most of the chute. Fish bones littered its dry bed just upstream of the dam, the last place that dried out.

A dead gar in Chartres Island Chute upstream of closing dam, 2012

Chartres Chute Plunge Pool, 2012

At low water, an arbitrary number set on the flood gage at St. Louis, the plunge pool downstream of the dam is ten feet deep and the only place fish can wait out a drought or, in good times, the winter.

 

 

 

 

 

 

 

 

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.

Tap the Mississippi to Relieve the Parched West and the Colorado River

Colorado River runs through the Grand Canyon near Peach Springs, Arizona

The Colorado River is tapped out. So the Bureau of Reclamation and the people who live in the Colorado Basin are eyeing the Mississippi to relieve some of the demands we have put on the Colorado.

The Bureau of Reclamation?: Think the Corps of Engineers for the western states. While the job of the Corps of Engineers is to control flooding on the Mississippi and its tributaries, the job of the Bureau of Reclamation is get water for drinking and irrigation to the parched states west of the Great Plains. It also provides hydroelectric power to those states. Where the Corps of Engineers manages the Mississippi, the Bureau of Reclamation manages the Colorado and the Columbia.

To get water to all those farmers and electricity to all those cities it has dredged canals and constructed dams and power plants. It has also allowed the sparsely settled west of the early 20th century grow into the densely populated cities of the 21st. All those people and all those farmers need water to irrigate their lawns and their vegetable crops and to light their cities. Actually, the farmers are competing with the city dwellers for water and when push comes to shove the farmers lose.

Lake Mead

It took 19 years to fill Lake Mead, upstream of the Hoover Dam, to 24 million acre-feet. Between 1998 and 2007, Lake Mead, which serves Las Vegas and its surrounds, lost 54% of its water.

Lower Mississippi at Riddles Point, Missouri south of the Ohio

One solution is to tap the Mississippi River just below its confluence with the Ohio and send the water to the Navajo River in southwest Colorado through a 775 mile=long pipe 144 inches in diameter. From their it would flow to the San Juan River, a tributary of the Colorado. Agricultural users in Colorado, Arizona, and New Mexico would cease their demands on the Colorado, leaving it free to serve the cities. The history of the Corps of Engineers’ interventions on the Mississippi River is the story of the law of unintended consequences.

To repeat what I have written before in The Mississippi:

“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.”

According to Amy Joi O’Donoghue, who had written an excellent series of articles in Deseret News, which is published in Salt Lake City, folks in Utah and other states served by the Bureau of Reclamation look at the Flood of 2011 and say the Mississippi has more water than is needed in the Midwestern and Southern states that border it.

Breton Sound: Bohemia Wildlife Management Area

But the Louisiana coastal marshes, particularly those in the Barataria Basin and Breton Sound, need the fresh water and mud that the Mississippi delivered to the Gulf of Mexico during floods like that of 2011 to rebuild its wetlands and protect its cities, including New Orleans. The cities along the Mississippi Gulf Coast, which were wiped out during Katrina, could also use some solid wetlands out front in the Gulf of Mexico. During the BP Flood of Oil in 2010, freshwater flowing out of the Mississippi helped push some of that oil away from the wetlands.

Barataria Basin: Fresh Marsh, Jean Lafitte National Historical Park, Barataria Unit

So yes, we in the Mississippi River Basin occasionally have way too much water, but tapping the Mississippi year after year, flood or drought, could have the kind of unintended consequences that building the levees had and that constructing the dams on the Missouri had on the Louisiana Coast.

The time is fast approaching when we Americans are going to have to sort out how we manage freshwater, be it in the Mississippi Basin or in the Colorado Basin and other western river basins.

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;

Asian Carp and the American Bottom Borrow Pit

American Bottom: Jefferson Barracks Borrow Pit

I don’t think the farmer who tills this field just east of the Jefferson Barracks Bridge that connects St. Louis County, Missouri to Monroe County, Illinois calls the borrow pit that lies between the levee and his wheat field the Jefferson Barracks Borrow Pit, but I do, because I have been watching and making photographs of it for the last two years. The field and the borrow pit have been flooded for the better part of three years and it really flooded this year. But we had a dry summer–after a real winter with snow, particularly up north and west, and a very wet spring–and the field dried out. So did the borrow pit.

When a levee district builds a levee, it takes the soil for the structure from a borrow pit on the riverside of the levee. When the river floods, it pours water into the borrow pit, filling it. It also delivers two or three inches of sediment to the borrow pit with each flood. Flood after flood has filled this pit with mud. In a really big flood, like the one we had this year, fish swim into the field and the borrow pit. In earlier years, before the pit filled with mud, it was a good fishing pond because it retained water and fish.

Egrets feeding on fish in a borrow pit puddle

As the flood drains away the fish are corralled into the lowest points in the field/borrow pit and the egrets and other wading birds move in and feed on the fish.  Gulls follow the egrets. When the borrow pit completely dries out, the raccoons arrive.

Dead fish, mostly Asian carp, in the Jefferson Barracks Borrow Pit

When I was researching The Mississippi: A Visual Biography, I learned effort to create the Upper Mississippi Fish and Wildlife Refuge started with fish rescue. When the river flooded, fish would swim into the shallow side channels of the river. When the flood receded, the fish would be trapped. When the side channels dried out, the fish would die. Conservationists in the 1920s would rescue fish from the side channels before they dried out. When confronted with the field of dead Asian carp, no one is particularly interested in fish rescue.

Paddlefish and Asian Carp

However, Asian carp are no the only fish which ventured into this field. So did paddlefish and blue gills.

Two carp and a blue gill

It has been just under twenty years since the Flood of 1993 when the first Asian carp escaped catfish farms and invaded the Mississippi, clouding out other species. Now when the Mississippi floods and the flood recedes, stranded Asian carp pepper the landscape. Here and there are interspersed a few desirable fish–like paddlefish and blue gills.

Wheat Field and dead carp

The farmer who tills the field between the borrow pit and the river was optimistic this fall and planted wheat in the field. In doing so, he tilled Asian carp carcasses into his field. If the farmer is lucky, the field won’t flood before the wheat is ready for harvesting next June.