Unrealized potential for Louisiana Delta habitat restoration

Imagine a cement truck diverted from its destination where builders eagerly await the foundational load.

Louisiana Delta

NEW ORLEANS — Imagine a cement truck diverted from its destination where builders eagerly await the foundational load. Now picture hundreds of cement trucks rerouted daily from construction sites to vacant lots, and you'll understand one of the biggest frustrations facing Louisiana bass anglers as well as other proponents of the state's coastal wetlands restoration.

 The problem: Too much Mississippi River water remaining in the Mississippi River. For decades, Louisiana's wetlands, along with the bass they support, have faced the looming specter of diminishing delta acreage. Tidal erosion assaults many of the world's seashores, but the Mississippi Delta has also suffered from what has not happened — specifically, the employment of freshwater diversion projects for wetland restoration.

 Aptly describing the Big Muddy's flow as the "lifeblood" of Bayou State wetlands, Louisiana Sportsman Editor and avid bass angler Todd Masson said: "The majority of the Mississippi River's sediment-rich flow continues rolling over the continental shelf, where it does the marsh no good."

 Indeed, the river's natural distribution network has been disrupted, but alternate routes are woefully underutilized. Here's the background: Prior to the 20th century, the Mississippi River's southern tributaries and periodic flood waters sent millions of tons of sediment and nutrients into coastal marshes. This alluvial nourishment provided foundation and food for expanding plant life, which anchored the marsh bottom and encouraged wetland expansion.

 These wetlands buffer storm surge, and they offer boundless recreational opportunities, from duck hunting to bass fishing. According to some estimates, Louisiana loses some 25 square miles of wetlands annually, and man's devices are mostly to blame.

 A price of progress, the levees that have spared southern Louisiana's residential and commercial properties from annual floods have actually doomed a significant element of the area's charm by starving the wetlands of sediment and nutrients. Simple levees built by local farmers date back to the early 1800s, but the great flood of 1927 prompted the U.S. Army Corps of Engineers to construct a modern system of walls that corral the river from just south of Baton Rouge to its southern terminus. Delta life is now safer, but wetlands have suffered.

 Saltwater recreational anglers, as well as commercial fishermen — chiefly oystermen — lament the loss of outer marsh habitat where they operate in brackish to saline waters. At the other end of the system, bass anglers decry the Gulf's northward march, as saltwater intrusion kills plants that provide habitat for bass and the forage they seek.

 Life without levees is unthinkable, but the freshwater diversions cut through key locations hold tremendous wetland restoration potential — if only water were allowed to flow through them. Louisiana's water managers realize this, but the primary mission currently overrides a positive byproduct. Bottom line: Diversions are officially viewed as tools for salinity regulation, not coastal restoration.

 "The state would like to allow higher flow rates more often, but because of an agreement between the state and the commercial fishermen (primarily oystermen) and the Corps of Engineers, the diversions are almost only used to hit salinity targets in the basins," said Chris Macaluso, Coastal Outreach Coordinator for the Louisiana Wildlife Federation. "Those salinity targets are based upon environmental impact studies conducted decades ago, when coastal erosion wasn't such a prominent issue."

 The main diversions at Caernarvon (East Bank, 15 miles downstream from New Orleans) and Davis Pond (West Bank, 23 miles upstream from New Orleans), along with a handful of smaller projects and siphons (hoses running over the levees) typically run at only a fraction of their capacities. For example, Caernarvon can send 8,000 cubic feet per second (cfs) of river water into the Breton Sound estuary, while Davis Pond's capacity of 10,650 cfs would greatly benefit the Barataria Basin. Flow rates vary with river height, but neither diversion runs at even a quarter of its capacity.

 Many believe that increasing diversion flow would profoundly benefit coastal wetlands by sending more sediment and nutrients into the marsh. Macaluso said the notion is working its way through the bureaucratic process.

 "Right now, the state and the [Army Corps of Engineers] are examining ways in which the diversions can be used to maximize their delivery of freshwater and sediment, rather than just sticking to the salinity targets," Macaluso said. "That comes as a result of the 2007 Water Resources Development Act which instructs the Corps and state to examine the diversions. But, it does not require them to be operated differently."

 The recent BP Deepwater Horizon disaster bolstered the case for increased diversion use, as the structures ran at full capacity for several weeks to repel oil headed for delta marshes. Downstream areas saw tremendous increases in bass fishing and while the immediate influence was current and overwash of baitfish, those who monitor the coastal zones believe such robust flows would deliver even more long-term benefit.

 For example, Lake Cataouatche, situated below the Davis Pond diversion, has become one of southern Louisiana's hottest bass spots. Since the project opened in 2002, anglers such as Bassmaster Elite Series pro Greg Hackney have found quantity and quality abounding in this wetland fishery, and expanded aquatic plant growth generated by diverted river water deserves the credit. The area is expected to play heavily in the outcome of the 2011 Bassmaster Classic in New Orleans, Feb. 18-20.

 Gary Tilyou, administrator for Inland Fisheries with the Louisiana Department of Wildlife and Fisheries, said that while Hurricane Katrina scoured the areas downstream of the Davis Pond diversion in 2005, these waters are now thick with hydrilla and other aquatic plants that have ignited phenomenal bass fishing similar to the bonanza seen in the Delacroix marsh shortly after Caernarvon's 1991 opening.

 "Diversion flow has really expanded where bass can survive," Tilyou said. "Now, about 80 percent of the Lake Cataouatche area has hydrilla. After Hurricane Katrina washed a lot of saltwater in there, the marsh was on its way back; it was freshening up. Obviously the more water you pump down there, you're going to increase the areas where hydrilla can even grow. This expands the edge effect, where you have more surface between brackish and freshwater. More animals can tolerate that area and usually there's more food there. Shad, bream, shrimp and bass may even grab a menhaden along the brackish edge."

 Anecdotal evidence of improved bass fishing and wetland restoration stemming from freshwater diversions is not hard to come by, but neither are the nay votes. Louisiana faces a tough dilemma as the levees, while essential, have disrupted the river's deltaic cycles at the expense of coastal wetlands. Debates over short-term impacts to commercial fisheries versus long-term sustainability are not easily moderated, but one staggering point remains absolute: As talks continue, so will the loss of 25 square miles a year.