What Went Wrong
The Mississippi River Delta is disappearing at an astonishing rate: A football field of wetlands vanishes into open water almost every hour. Since the 1930s, Louisiana has lost nearly 1,900 square miles of land, an area roughly equivalent in size to the state of Delaware.
Many factors have led to the delta’s collapse.
One of the most significant is that the lower Mississippi River has been straitjacketed with huge levees as part of a national program to “control” the Mississippi River and protect communities and economic infrastructure from river flooding. But the delta’s wetlands were built and sustained by sediment delivered by the river.
Cutting the river off from its delta with levees doomed existing wetlands and largely stopped the cycle of new wetlands growth.
Without land-building deposits from the river, the delta is doomed to continue sinking beneath the water, endangering the people, wildlife and jobs that depend on these healthy natural resources
But there are other factors at work:
- Oil and Gas Infrastructure
The Delta is home to thousands of offshore oil rigs and onshore wells, significant refinery capacity and thousands of miles of pipelines connecting it all. Canals cut to service these wells have acted as a highway for salt water intrusion. Over the decades, these activities have directly impacted thousands of acres of coastal wetlands, speeding up erosion.
Land formed by river sediments naturally subsides and sinks over time. Historically, sediment deposition and build-up from plant growth outpaced the natural subsidence, resulting in coastal land gain. Without land-building deposits from the river, subsidence dominates and massive areas of land are sinking below sea level and disappearing.
Storm surge from Hurricanes Katrina and Rita destroyed hundreds of square miles of coastal wetlands. The continued loss of wetlands will make coastal communities such as New Orleans even more vulnerable to storms.
- Dams Upriver
Valuable land-building sediments are trapped behind locks and dams on the Missouri, Mississippi and Ohio Rivers. Since 1850, the amount of sediment in the Lower Mississippi River has decreased by more than 70 percent.
- Sea level rise
Scientists say that the level of the world’s oceans will rise from one to three feet over the next century. Rising seas combined with subsiding land (called “relative sea level rise”) makes the threat of submergence even greater for the Mississippi River Delta. When wetlands receive sufficient sediment from the river, they can stay above the rising seas.
These fast breeding, voracious rodents were introduced into Louisiana for the fur trade, but their impact on coastal wetlands has been disastrous. They burrow into the ground, eat the roots of marsh plants, and devour cypress seedlings, harming wetlands as they go.
- 2010 Gulf oil spill
The BP Macondo well spewed 206 million gallons of oil into the Gulf, affecting hundreds of miles of delicate shoreline, thousands of acres of coastal marsh, and disrupting the communities, economy and wildlife of the coast. The spill will continue to impact the coast and its inhabitants for decades to come.
There is a Solution!
Solutions do exist that can reverse the land loss and start building land, but it’s going to take a comprehensive science-based plan to do it. The science is telling us that we have to get started soon, before it is too late.
- Two Sides of the River
- How Long Must We Wait?
- Mississippi Land & Lodges: A Report on the Vanishing Paradise [pdf]
- Outdoor Life: The Biggest Habitat Catastrophe You’ve Never Heard Of
- Restoration Solutions for the Mississippi River Delta