The Gulf Coast: A Model for Coastal Restoration

The 2012 hurricane season also brought Isaac, a Category 1 hurricane, ashore at the mouth of the Mississippi River, near New Orleans, La. A large hurricane with a sizeable storm surge, with surge ranging from 10 to 14 feet, Isaac caused about $2 billion in damage. We are reminded that the damage wrought in 2005 by the deadliest and most destructive storm in U.S. history: Hurricane Katrina caused $108 billion in damage.

During Hurricane Isaac, in the Greater New Orleans area, surge flooding was prevented by USACE’s $14.6 billion Greater New Orleans Hurricane and Storm Damage Risk Reduction System, a network of levees, floodwalls, pump stations, floodgates, outfall canals, and surge barriers built to reduce the risk of flooding from a storm having a 1 percent chance to occur every year. Outside this perimeter system, surge flooding occurred in the coastal parishes of Louisiana and river flooding occurred in parts of Louisiana and Mississippi, reminding all of the damage that can be wrought by nature.

The Half Moon Reef in Matagorda Bay, Texas, was once a thriving 400-acre oyster reef, one of the most commercially important on the mid-Texas coast, but it’s largely devoid of life today. In spring 2013, Galveston District, in partnership with The Nature Conservancy, launched the effort to restore a 12-acre portion of Half Moon Reef – the first step in a more extensive 60-acre restoration.

For more than two decades, USACE’s New Orleans District has participated in some of the nation’s most mature and far-sighted coastal restoration programs, in the largest expanse of coastal wetlands in the contiguous United States – a region that, in the late 20th century, was losing 35 to 40 square miles of coastal wetlands every year to erosion. As of summer 2013, due in part to multiple outreach programs, management improvements, and coastal protection and restoration projects, those losses had been reduced to about 16.5 square miles annually. Coastal restoration is important for the future of Louisiana; the disappearance of wetlands threatens the productivity of its coastal ecosystems, the economic viability of its industries, and the safety of its residents.

New Orleans District, along with support from other USACE districts and from the Engineering Research and Development Center, has played a leadership role in many of these efforts – and continues to do so, as coastal Louisiana is threatened by a combination of factors including rising sea levels, saltwater intrusion, the subsidence (sinking) of existing landforms, hurricanes, and human activity. Coastal restoration efforts in which the district is currently engaged include:

• The Beneficial Use of Dredged Material (BUDMAT) program – As in the northern Atlantic and in Florida, USACE has found its navigation and coastal restoration missions to be of mutual benefit: Material dredged to clear federal navigation channels – such as the Mississippi River – is used to create wetlands that provide critical habitat for many species and help dampen the severity of storm surges. Today, nearly 40 percent of the material dredged under the district’s O&M program that is suitable for beneficial use is used for this purpose, and to date, USACE has created more than 31,000 acres of land in Louisiana’s coastal wetlands through BUDMAT.

• The Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) program – The CWPPRA program funds smaller-scale, cost-effective coastal wetland projects and utilizes the expertise of several federal agencies and the state of Louisiana to do so. Since 1990, CWPPRA has protected, enhanced, or restored 113,000 acres of Louisiana wetlands; as of June 2013, 99 of 196 existing CWPPRA projects had been completed and entered the O&M phase.

• The Louisiana Coastal Area (LCA) Ecosystem Restoration program – Authorized by the Water Resources Development Act of 2007, the LCA Program establishes a systematic approach to coastal restoration, combining critical near-term restoration projects with larger-scale, longer-term programs aimed at restoring natural landforms and ecological processes. With an overall goal of slowing the trend of wetland loss and resource degradation, the LCA is a federal/state partnership, consisting of 15 projects subject to feasibility studies, a BUDMAT program, a Demonstration Projects (DEMO) program, and the Mississippi Hydrodynamic and Delta Management Study. Given the diversity of coastal habitats on the Louisiana coast, including natural ridges, barrier islands, forested swamps, and marshes running the full freshwater to saltwater spectrum, the LCA program employs several restoration techniques, including marsh creation, barrier island restoration, and river diversions. Many LCA projects are located in the delta plain of southeast Louisiana, where wetland losses have been the most severe.

Galveston District

On Texas’ often hurricane-battered 367-mile coastline, Galveston District – which began making harbor and shoreline improvements in 1880 – oversees another diverse and systematic coastal restoration program. Its BUDMAT program, drawing material from more than 1,000 miles of navigation channels, is one of the most expansive in the country, according to Janelle Stokes, the district’s regional environmental specialist: “We’re second to New Orleans in the amount of dredged material we move every year – and we’re similar to New Orleans in that we have mostly fine-grained material, not sand. So we build beaches where we have sand, which is mostly in south Texas.” Much of the finer-grained material is used to create barrier islands or marshes. “Right now, for example,” Stokes said, “we’re using dredged material from the Texas City Channel to create a large acreage of marshland. We’re going to create a thousand acres of marsh every 30 years.”

Other beneficial use projects under way in Texas include the construction of a breakwater along the Gulf Intracoastal Waterway adjacent to the Aransas National Wildlife Refuge in parts of Aransas, Regugio, and Calhoun counties. Material deposited behind the breakwater, said Stokes, will create and protect valuable habitat for an endangered whooping crane population.

Galveston’s coastal restoration program includes the restoration of oyster reefs. Oysters are filter-feeding organisms that anchor the coastal marine food chain, offer protection from storm surges, and help keep coastal waters free of sediment and algae. Hurricane Ike, in 2008 – the costliest hurricane in Texas history – destroyed 8,000 acres of oyster reefs alone, and the extent and quality of existing oyster reefs has been further depleted by overfishing, shell dredging, hydrologic changes, and other factors.

The Half Moon Reef in Matagorda Bay, Texas, was once a thriving 400-acre oyster reef, one of the most commercially important on the mid-Texas coast, but it’s largely devoid of life today. In spring 2013, Galveston District, in partnership with The Nature Conservancy, launched the effort to restore a 12-acre portion of Half Moon Reef – the first step in a more extensive 60-acre restoration.

USACE is careful, in its considerable dredging operations along the Texas coast, to protect the sea grass beds that help to stabilize shoreline and provide valuable habitat for fish and other species. In sensitive areas – such as the Laguna Madre, a long, shallow, saltwater lagoon spanning five Texas counties on the state’s southern Gulf Coast – Galveston District limits its dredging operations to the winter, when sea grasses are dormant, and regularly supplies beds with thin nourishing layers of material from nearby navigation projects. Sea grass protection is a small, but crucial, component of the district’s coastal restoration program, which applies more than a century of lessons learned along Texas’ Gulf Coast.