of the flow to enter the Atchafalaya. The remaining 70 

 percent continues past Baton Rouge and New Orleans 

 to the Mississippi's present delta in the Gulf. With the 

 completion of the Old River Control Structure, the Mis- 

 sissippi River appeared tamed. 



It was obvious even in the 1950s that the sediments 

 created by the perennial spring floods were no longer 

 reaching their natural resting grounds in levees, swamps, 

 and marshes. At the time, that seemed a blessing. The 

 primary effect, however, was to restrict sedimentary land 

 buildup to two isolated locations on the coast: at Head of 

 Passes, seventy miles southeast of New Orleans, where the 



Wetlands in New 

 Orleans. One restora- 

 tion project, which has 

 been operating since 

 1991, pumps fresh- 

 water into wetlands 

 below New Orleans. 

 The project is intended 

 to mimic the natural 

 over-bank flooding that 

 built the delta in the 

 first place. The project 

 is a valuable model for 

 restoration techniques, 

 but it has had the 

 unwanted effect of 

 disrupting seafood 

 harvesting. 



Mississippi River reaches the Gulf, and at the Atchafalaya 

 River outlets, south of Morgan City. Elsewhere across 

 Louisiana, coastal land loss continued to worsen. 



But the downside of flood control is not limited to re- 

 stricting the natural dispersal of sediments. It also interferes 

 with the dispersal of nutrients across the delta. Even before 

 the twentieth century, conservationists noted that altera- 

 tions to the river were causing entire ecosystems to decline 

 at some distance from the main stem of the river. Years 

 after the levees and spillways were completed, investiga- 

 tors from the Louisiana Universities Marine Consortium 

 discovered a "dead zone" of water spreading out into the 

 Gulf of Mexico from the shoreline at the mouth of the 

 Mississippi. At times it covered an area as large as New 



Jersey. Devoid of dissolved oxygen, the dead zone owed 

 its existence to massive flows of fertilizers collected by 

 the Mississippi and its tributaries. 



Flood control and its multiple ramifications had set the 

 stage for disaster. 



n 1989, finally prodded into action, the Louisiana leg- 

 islature established the Louisiana Wetlands Conserva- 

 tion Authority, and Congress subsequently passed the 

 Coastal Wetlands Planning, Protection, and Restoration 

 Act of 1990 (CWPPRA). By then, the total funding for 

 various state and federal coastal restoration programs in 

 Louisiana exceeded $50 million a year. 



One of the first restorations was the Caernarvon Fresh- 

 water Diversion Project, which began operating in 1991. 

 Planned prior to CWPPRA, the project called for discharg- 

 ing as many as 80,000 gallons of freshwater per second 

 into the swamps, marshes, and shallow bays east of the 

 Mississippi River and downstream from New Orleans, 

 in Saint Bernard and Plaquemines parishes. The project 

 consisted of a set of diversion gates built through the 

 existing flood-control levees; the flow through the gates 

 was intended to mimic the natural over-bank flooding 

 that had built the delta in the first place. 



Since 1991 the Caernarvon project has become a model 

 that has afforded valuable practical experience with res- 

 toration techniques. It has also had unwanted effects. 

 For example, the freshwater diversion project disrupted 

 seafood harvesting by coastal communities, and as a result 

 of lawsuits brought against the project, local oystermen 

 have been awarded more than $1 billion in damages. 



From 1991 until 1998, more than forty-five projects 

 were begun under the auspices of the CWPPRA. But it 

 soon became obvious to both state and federal governments 

 that addressing coastal land loss in Louisiana far exceeded 

 the scope of the original CWPPRA legislation. A new 

 effort, known as Coast 2050, was set up to evaluate and 

 plan for a larger-scale restoration of coastal Louisiana. 

 That work resulted in a plan with an anticipated price of 

 $14 billion. The Coast 2050 effort subsequently evolved 

 into the Louisiana Coastal Area Ecosystem Restoration 

 Project, or LCA, in which I participate as a geologist. 



More than a hundred restoration projects are now ac- 

 tive, but they are experimental, and their scale is such 

 that even collectively they have relatively little impact on 

 the fundamental problems. In the wake of the storms of 

 2005, however, public sentiment would support a more 

 comprehensive effort to address coastal restoration. 



There is no handbook on the subject. What we already 

 know and what we are learning is contributing to the 

 foundation of the emerging field of environmental restora- 

 tion science. If we can apply the science fast enough, we 

 may be able to keep Louisianans' homes and heads above 

 water. The overriding lesson we've learned is the deadly 

 hazard of playing around with rivers. □ 



52 



natural history November 2007 



