Sediment removal to enhance water quality at constructed wetland

The Governing Board of the South Florida Water Management District (SFWMD) approved $1.8 million in funding for maintenance dredging at Stormwater Treatment Area 5 (STA-5) in Hendry County. By removing excess sediments, the effort will enhance water quality and overall performance of the constructed treatment wetland, which contains nearly 6,200 acres of treatment area to remove phosphorus and other nutrients from water before it enters the famed Everglades...

• Maintenance dredging to optimize Everglades treatment wetland

WEST PALM BEACH, FL, March 3, 2008 -- The Governing Board of the South Florida Water Management District (SFWMD) approved $1.8 million in funding for maintenance dredging at Stormwater Treatment Area 5 (STA-5) in Hendry County. By removing excess sediments, the effort will enhance water quality and overall performance of the constructed treatment wetland, which contains nearly 6,200 acres of treatment area to remove phosphorus and other nutrients from water before it enters the famed Everglades.

STA-5, one of six treatment wetlands across the Everglades Agricultural Area south of Lake Okeechobee, was built to improve the quality, timing and distribution of water entering the northwest portion of the remnant Everglades known as Water Conservation Area 3A. From May 2006 through April 2007 (known as Water Year 2007), the natural treatment facility successfully retained 8.8 metric tons of phosphorus. Together with best farming practices, the District's 52,000 acres of STAs have prevented more than 2,700 metric tons of phosphorus from entering the Everglades since 1994.

"Maintenance activities in and around the STAs are essential to the District's mission of environmental restoration," said SFWMD Governing Board Chairman Eric Buermann. "Even low-profile projects such as sediment removal are needed to sustain our success in improving Everglades water quality."

Phosphorus-laden sediments have built up over the years along the bottom of conveyance routes that direct water into the STA for treatment, including the L-3 Borrow Canal, upstream of STA-5 inflow structures and the spreader canals within STA-5. Removing these accumulated sediments will keep the STA functioning well and allow the wetland to continue improving the quality of water flowing into the Everglades.

The maintenance work involves dredging two miles of the L-3 Borrow Canal and 4.2 miles of spreader canals. The dredged material will be disposed of within STA-5 in an area adjacent to the L-3 Levee, but outside of the STA's treatment cells.

Throughout the Everglades Agricultural Area, water quality improvements are being achieved through a commitment by the State of Florida and the South Florida Water Management District, which have invested $1.8 billion for this effort. Another $250 million is committed to improving Lake Okeechobee and the Northern Everglades, which will further enhance water quality throughout the entire Everglades ecosystem.

In addition to the role of STAs in water quality improvements, treatment wetlands also offer unique recreational opportunities for residents and tourists alike. The wetlands particularly at STA-5 provide ideal habitat for migratory waterfowl and are often ranked among the best waterfowl hunting sites in the nation. STA-5 also is ideal for bird watching, with seasonal tours provided by the Hendry-Glades Audubon Society.

The South Florida Water Management District is a regional, governmental agency that oversees the water resources in the southern half of the state -- 16 counties from Orlando to the Keys. It is the oldest and largest of the state's five water management districts.

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