May-June 2006

Wetlands

Lose or restore?

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By Roberta Baxter

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Wetlands are some of the most valuable and yet most overlooked resources in our country. For years, we have drained, cut off, and destroyed wetland areas to provide more farmland, flood control, or recreational facilities. Wetland acreage has shrunk drastically in the past 100 years, but some progress toward restoring these resources is being made.

Wetlands are valuable as habitat for wildlife, fish, and birds; as protection from storm surge; and as recreation areas. Half of the population of the United States lives along the coasts, where many marsh and wetland areas are affected, but, as well as along the seacoasts, many wetland areas occur naturally in other parts of the country.

Losing Louisiana
Louisiana has the largest coastal wetlands in the United States. The state also accounts for about 90% of the coastal marsh lost each year in the US. Approximately 70% of waterfowl species migrate through Louisiana, and loss of habitat affects their numbers. The fishing industry in Louisiana is the largest in the lower 48 states, and this industry relies heavily on wetland habitat. Since the 1930s, Louisiana has lost 1.2 million acres of wetlands. In the 1970s, the loss was calculated at 25,200 acres per year. By the 1990s, conservation efforts had slowed the loss to 15,300 acres per year, and the estimate for 2000 on was 6,600 acres per year. The challenge is to decrease these losses even more and to restore damaged wetlands.

Dredging a shallow water canal
Constructed terraces and wetland vegetation from the air

Reasons for losses include natural and manmade factors, and many areas must be considered to prevent further destruction. After the recent hurricanes, many area residents contended that previous loss of wetlands and barrier islands increased the damage. Studies are being conducted to see how this can be prevented in future storms. Human factors can drastically change the hydrology of an area, affecting the wetlands. As an example, levees along the Mississippi River provide flood protection but also prevent sediment buildup essential for wetland health.

The Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) was passed by Congress in 1990 to address these issues. Also known as the Breaux Act, this law has supported more than 150 projects around the country, especially in Louisiana.

Wilco Industrial Services Inc. in New Roads, LA, and its sister company, Wilco Marsh Buggies in Harvey, LA, are one of the leading wetlands restoration outfits in the Gulf Coast region. Executive Vice President Micheal Johnson notes that the companies have been involved in numerous restoration projects.

One project was carried out on and near the Rockefeller State Wildlife Refuge in Cameron and Vermilion parishes. The project goal was to restore intermediate and brackish marshes. High water levels were found in the Lakes portion of the project, due to a highway and a gate and locks system designed to prevent flow of saltwater into nearby lakes. Another sub-basin, the Chenier, suffered from high salinity, and that caused loss of marsh habitat.

Wilco Industrial dredged the existing shallow water canal and installed four 42-inch pipes to provide water control in both directions. This technique gives control of both water level and salinity by allowing the flow direction to be driven by current conditions.

The next step was the installation of 26,000 linear feet of earthen terraces. The terraces trap sediment, creating a marsh area, and reduce erosion caused by wind-driven wave action. Wetland vegetation was planted on the terraces. Construction of the terraces provided about 14 acres of marsh.

A joint project between Wilco Marsh Buggies and Dredging Supply Co. of Reserve, LA, produced an innovative piece of equipment. One disadvantage of the bucket dredge is that as a channel is dredged and the sediment is piled on the bank, the channel is deepened. To keep this from happening, the refuse can be trucked away, but this involves high transportation costs and the need for a disposal area. The Amphibian Spray Dredge disperses the sediment over a larger area, depositing only small amounts in any one place. This dredge is also built to be used in shallow water and minimizes impact to the ecosystem.

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Industrialized Massachusetts
Chelsea, MA, is one of the most urbanized towns in the United States. Local officials contacted the National Oceanic and Atmospheric Administration (NOAA) to propose a wetland restoration in the area. Mill Creek, the headwaters of Chelsea Creek, is Chelsea’s only remaining salt marsh and only site not designated for industrial use. A section of the heavily industrialized creek was chosen as a pilot site for wetland restoration. The 0.75-acre site is surrounded by a shopping mall, public housing, and a busy highway.

Limited water flow and sediment buildup had severely crippled the creek. Salinity in the site had dropped to extremely low levels because of runoff from impervious areas of the shopping mall and the highway. The lower salinity levels increased the growth of the invasive Phragmites australis, crowding out the native salt marsh hay (Spartina patens) and saltwater cordgrass (Spartina alterniflora). The area was unattractive to nearby residents, increasing their view of it as a dumping ground. Next Page >

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