Environment
 

Dam it: Fishers frustrated by closing of MRGO, but some catches increase

Some fishers claim the rock dam built across the MRGO in 2008 to block storm surge has hurt fishing

Photo by U.S. Army Corps of Engineers

Some fishers claim the rock dam built across the MRGO in 2008 to block storm surge has hurt fishing

Robert Campo was born 46 years ago to a family of famous Shell Beach fishermen. Over the course of his life, he has seen the rapid erosion of the surrounding wetlands that sustain his community, industry and unique culture. Further, that loss has created a rising threat from hurricane storm surge and portends an eventual end to one of the nation’s most productive fisheries.

Much of that loss was caused by the Mississippi River-Gulf Outlet, a 70-mile shipping channel sliced through the heart of the eastern St. Bernard Parish wetlands from New Orleans to the Gulf. Long considered one of the worst environmental and economic disasters in state history, a cheer went up from coastal advocates in 2009 when that big canal was plugged with a rock dam near its southern end, and multi-billion dollar restoration plans were announced to rebuild the marshes with sediment and fresh water from the river.

But Campo and other fishers in the area didn’t celebrate. They are no fans of this particular  restoration effort.

“I knew when they plugged the channel things could get worse, and they have,” said Campo, who helps run his family’s marina and live-bait business.

“Restoration is suppose to help us, but this is just hurting us. Eventually it could kill us.”

It’s conventional wisdom that everyone wants to restore Louisiana’s crumbling, sinking coast.

But when “restore” actually means returning things to the way they once were, support can drop.

To people whose lives have been tied to the state’s coastal wetlands neighborhood the way it has devolved over the past 70 years, restoration is like gentrification. They fear the newcomers are pushing them out.

Fishers prospered as the delta became saltier

Seven decades ago the MRGO opened an expressway for salty Gulf waters and stronger tides into the Lake Pontchartrain-Borgne basin. After that, fishers enjoyed record catches of  speckled trout, redfish, shrimp and crab. Naturally, they worried about what would happen when the channel was closed and those conditions changed.

Six years later, some of them think they know the answer. Campo said fishing success has fallen since the repairs have begun.

He blames the dam on the MRGO for blocking saltwater and important tidal currents from the Gulf, and the diversion of freshwater from the river into area wetlands through the Violet Canal.

“The combination of that dam and the Violet siphon have changed everything,” he said. “The water’s just too fresh. Trout fishing is down, shrimping is down, and crabbing is way, way down.

“And trying to keep bait alive is twice, three time as hard. The water is so fresh in the canal and bayou, we got to put salt in our tanks to keep croakers alive.”

George Ricks, the charter-boat captain heading the Save Louisiana Coalition which opposes some of the state’s restoration plans, said the MRGO efforts have only made things worse for fishers.

“It’s killed salinity and increased the dead zones,” he said.  “Restoration is supposed to help things, not hurt them.”

Recent scientific reports support some of the fishers’ contentions.

A scientific look

Research on post-dam conditions by U.S. Geological Survey and the University of New Orleans found substantially fresher conditions north of the rock barrier while the Gulf side has saltier water and an expansion of areas with low oxygen in the summer. The research also pointed to less saltwater intrusion and fewer low-oxygen areas in Lake Pontchartrain.

But six years may be too short a time span to predict lasting changes, said John Lopez of the Lake Pontchartrain Basin Foundation.

“You generally need a longer time period to account for significant, unrelated events that can affect those factors,” he said.

For example, two dramatic events lowering salinities occurred in two of those six years.

During the BP oil spill in 2010, Gov. Jindal ordered all siphons and diversions connected to the river opened in an effort to keep oil from invading the marshes. And in May and June of 2011, the Bonnet Carre Spillway was opened, allowing some of the  Mississippi River to flow into Lake Pontchartrain to reduce the flood threat to New Orleans. The USGS data showed a dramatic plunge in salinities during those periods.

Conversely, the USGS records show a spike in salinity in August 2012 – the period when Hurricane Isaac’s salty Gulf storm tides stayed in the basin for several days.

State records on commercial shrimp and crab catches in the basin actually show improved results overall after the changes were put in place.

Average annual catches before and after MRGO dam
Before dam After dam
Crabs 9.4 million pounds 12.3 million pounds
White shrimp 2.7 million pounds 3.6 million pounds
Brown shrimp 4.5 million pounds 2.5 million pounds

The figures represent the average catches in six years before the dam, not including 2005, which saw fishing come almost to a standstill after Hurricane Katrina, and six years after the dam, not including 2010, when the state closed the commercial fishing for several months.

Campo, however, says the long-term impact of the changes is easy to forecast: Fresher water and fewer trout, shrimp and crabs.

“I’ve lived here my whole life – 46 years – and we always had salinities in the lake (Borgne) 15 to 20 parts per thousand,” he said. “Now you go out even to the rigs in the middle of the lake, and you’re going to see 5 or 6 parts per thousand. Trout can’t live in that. They move.

“Heck, right now I can go out any day and catch a limit of green trout [largemouth bass, a freshwater species] off the MRGO.

“That isn’t normal.”

But Campo’s memories don’t match the historical record. Research published before the MRGO was completed in 1963 classified the Lake Pontchartrain Basin as primarily a freshwater system, with salinities averaging between 3 and 8 parts per thousand.

In fact Campo concedes his grandfather, Frank “Blackie” Campo, a legendary figure among local fishers, often talked about fishing for green trout and sac-a-lait (crappie) in local waters, as well as hunting duck species such as mallards that thrived in the freshwater swamps that dominated the area.

After the MRGO opened, that habitat began a slow but steady drift to saltier conditions, with studies showing increases of 4 to 6 parts per thousand. Eventually  that resulted in a dramatic change in habitat.

Moreover, the saltwater intrusion caused by the channel led to the loss of at least 55,000 acres of wetlands. This included some 22,000 acres of cypress swamps along the MRGO corridor. Another 10,000 acres of cypress died along the Lake Maurepas shorelines on the far western end of the basin.

Reports show the loss of those wetlands significantly increased storm surge against local levees and floodwalls. A paper published in 2007 in the Journal of Coastal Research referenced a modeling study indicating the wetlands that were lost to MRGO impacts could have reduced storm surge from Hurricane Katrina by 80 percent.

Indeed, it was the impact of Katrina putting St. Bernard communities under 12 feet of water that provided the impetus for beginning the long-discussed closure of the MRGO, and restoring the wetlands that were lost.

Yet stopping this basin’s destruction by the Gulf of Mexico may not be in the fishers’ immediate economic self-interest. Coastal researchers say the forces that made anglers homes more vulnerable to flooding are likely responsible for the steady increase in their fishing fortunes over the past few decades.

Habitat gets better as the system dies

That irony it is part of the natural cycle of coastal deltas, and that the area is most bountiful before it dies.

Large rivers such as the Mississippi carry so much sediment that a delta it builds eventually grows so large it becomes an obstruction to the river’s path to the ocean. As pressure builds against its flow, the river will cut a new course to the ocean, creating a new mouth where it begins building a new delta.

Without new layers of sediment from the river, the abandoned delta begins sinking under its own weight. Once solid shorelines become fragmented, what once was a largely freshwater system turns brackish to salty.

But research shows coastal deltas are at their most productive for fisheries during these last stages of life. The mixture of salt and fresh water, the growing acres of shallow ponds and lagoons and the increasing miles of shoreline all are conducive to the food chain supporting valued species such as shrimp, crabs, speckled trout and redfish.

However if the sinking continues, eventually the amount of marshes left will be overwhelmed by the expanse of open Gulf water, and fishery production will plummet.

Fishermen such as Campo say they are not opposed to increasing flood protection by rebuilding the sinking deltas. They just prefer to see the rebuilding done by pumping river sand into the wetlands, a process that would not dramatically reduce salinity levels. They would also like to see culverts placed in the rock dam to allow some salt water and current to flow back into the wetlands north of the structure.

“We know they ain’t gonna tear down that thing,” Campo said. “But if they put culverts, which they could close when a storm is coming, we could have the best of both worlds.

“We gotta get that salinity back up, or this fishing will never be like it was.”

Yet UNO researcher Martin O’Connell* said that outside the immediate area of the MRGO, salinity levels in the basin have always fluctuated between fresh and salty. It’s the nature of a coastal estuary, he said.

“This type of estuary is supposed to have plenty of (salinity) changes because of all the factors that can influence it,” he said. “You get a lot of rain and the rivers leading into the basin that can drop the salinity. You get a tropical storm that can push it much higher. And you have regular tides cycles.”

O’Donnell thinks the tales of outstanding fishing passed down by anglers over the decades took place in those pre-MRGO says when salinities were swinging in that natural rotation.

“This system will always be changing, in a state of flux,” he said, “but that’s the beauty of it.”

*Correction: An earlier version of this story misspelled his name.

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  • Scott Eustis

    Dr O’Connell !!!! happy St Patrick’s Day, Bob. <3<3<3

  • Scott Eustis

    by the way, thank you for this excellent article

  • Tim

    I have had this conversation countless times. People say, Let’s restore the natural coast, then they point to a historical map and say, This is what we want it to look like. But that is a contradiction. Nature is never static. Southeast Louisiana has been in flux for thousands of years. Has human activity interfered with natural change in a negative way? In many ways, yes. But this idea that we can “freeze” or hold the coast static has to be replaced with the acceptance that nature is always changing. Humans have the ability to adapt. We need to embrace that going forward.

    Peace,

    Tim

  • Pat Fitzpatrick

    The MRGO rock dam has changed salinities, but isn’t restoration. The east side of the rock dam suffers from low oxygen in the summer (confirmed by the USGS study). Also, many bayous that were connected pre-MRGO have been cut in half and blocked by the back levee canal fill in.

    I’ve included an image which shows this area pre-MRGO; the red shows the location of the MRGO, and the blue the backfill, cutting off the north-south bayou systems. The rock dam is further west and off the map. This is a 10-mile long region cut in half. This circulatory system should be restored. Otherwise, the salinity gradient could become abnormal, and perhaps already is, among other problems.

    Historically, the salinity in the area east of the rock dam was 10-25 ppt pre-MRGO. One can debate the proper salinity gradient near Shell Beach and west of the rock dam, but everyone should agree the area east of the dam should not be freshwater or suffer from hypoxia. Incidentally, I got the figure and salinity data from the following reference, who also taught me at Texas A&M: El-Sayed, S.Z. 1961. Hydrological and Biological Studies of the Mississippi River-Gulf Outlet Project. Texas A&M Research Foundation. College Station, TX. This report is now hard to find, and also no longer available on mrgo.gov. But I have a copy if anyone is interested.

    The latest MRGO restoration plans are at this link with some good ideas (http://www.usace.army.mil/Portals/2/docs/civilworks/CWRB/mrgo_eco/mrgo_eco.pdf ) but completely ignores the damage done on the east side.

  • Scuttlebutte

    “Moreover, the saltwater intrusion caused by the channel led to the loss
    of at least 55,000 acres of wetlands. This included some 22,000 acres of
    cypress swamps along the MRGO corridor. Another 10,000 acres of cypress
    died along the Lake Maurepas shorelines on the far western end of the
    basin.”

    There are obviously some quantifiable direct and indirect land losses associated with the MRGO, which include excavation of wetlands for canal construction, and erosion of the MRGO shoreline, but where is the linkage between elevated salinities and wetlands loss? The MRGO/IHNC only accounts for a small portion of the tidal exchanges of Lake Pontchartrain (Rigolets and Chef Pass account for the majority); as a result, the MRGO has probably only led to minor changes in salinity in the Lake Maurepas area (e.g., see http://geotest.tamu.edu/userfiles/167/50.pdf, http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA408114). From my understanding, the cypress mortality in the Lake Maurepas region may be more related to natural factors (such as subsidence), weather events (hurricanes, and the 1999-2001 drought, which promoted the introduction and prolonged residence of elevated-salinity waters), and perhaps local hydromodification (channels constructed for cypress logging).

    The author of the above statement does not indicate the type of land
    area change attributable to loss of cypress swamp (e.g., did the cypress
    swamp convert to marsh or open water?). For cypress swamp lost along the MRGO corridor, I would assume this could be attributable to excavation for MRGO canal construction and erosion of the MRGO shoreline, as well as more significant changes in salinity which lead to land area change (e.g., see the previously referenced publications). Natural factors, weather events, and hydromodification in addition to MRGO canal construction are probably also playing a role in the disappearance of cypress swamps along the MRGO corridor. I imagine it would be difficult to quantify to what degree these different factors have contributed to cypress swamp loss in the Pontchartrain estuary, and that simply blaming salinity intrusion is a cheap answer. Ultimately, preference of the Mississippi River to take the route of the Atchafalaya and sea-level rise would favor decay of these swamps (and an eventual conversion to open water) under more natural conditions.

    There only seem to be a handful of publications which have actually looked at salinity trends, changes in wetland habitat type, or tried to link salinity trends to changes in habitat type in coastal Louisiana (e.g., http://pubs.usgs.gov/of/2008/1127/, http://pubs.usgs.gov/of/2010/1282/, http://www.btnep.org/Libraries/Reports/Status_and_Trends_of_Hydrologic_Modification_Reduction_in_Sediment_Availability_and_Habitat_Loss_and_Modification.sflb.ashx). It appears salinity increases in Louisiana estuaries are localized and in proximity to long, straight navigation canals perpendicular to the coastline, such as the MRGO, Barataria Waterway, Houma Navigation Canal, and Calcasieu Ship Channel. In other words, salinity intrusion is more likely to be a localized phenomena, and probably isn’t contributing to land loss in coastal Louisiana on a large scale (or even a small one, as marsh types can change in response to salinity increases, not simply die). Habitat type, which is a proxy for long-term salinities, appear to fluctuate naturally, possibly owing to patterns in local weather and river discharge.

    Salinity intrusion is a cornerstone of restoration, with the motto being that intrusion is real, it kills wetlands, and we need to fix it by reintroducing the river into the estuaries…even though the areas where we would like to reintroduce the river would see very little river water under natural circumstances (i.e., if the Atchafalaya River would have captured the main flow of the Mississippi in the late 20th century like it was supposed to), even though the river today is very different from the river that built the delta (the wetlands might not like the industrial agricultural chemicals in river water, some of which may stunt root growth and promote root decay, making marshes more vulnerable to erosion/breakup), and even though we are headed towards a high-stand in sea-level and should thus naturally experience shrinking coastlines.