The Corps is working with its partners on various studies, new and ongoing, to understand and address the impacts this spillway opening will have on the local environmental and economic industry.
The Corps has coordinated with the Lake Pontchartrain Basin Foundation, Louisiana Department of Wildlife and Fisheries, the Louisiana Department of Environmental Quality, the National Marine Fisheries Service, the U.S. Fish and Wildlife Service, and the U.S. Geological Survey to proactively monitor current and future conditions in Lake Pontchartrain and vicinity. The Corps will continue to analyze samples until water quality parameters return to baseline conditions.
Water quality samples are being collected at five locations: one in the spillway, two at Causeway, and one each at Chef Menteur and the Rigolettes. The samples will be analyzed for nutrients, triazine herbicides, salinity, turbidity, dissolved oxygen, and many other parameters. In addition, field parameters, including salinity, are being collected at key locations in the Lake Pontchartrain Basin in between the weekly sampling. These samples are only a small part of the overall monitoring effort. For more information on the monitoring locations and samples, go to http://deltas.usgs.gov/BonnetCarre.aspx.
The Corps opened the spillway, located 28 miles above New Orleans, for the first time in 11 years on April 11 after heavy rains in the Mississippi and Ohio River valleys increased Mississippi River stages. The structure consists of 350 bays with 7,000 timber needles. The Corps opened a total of 160 bays within nine days. The flows passing through the structure averaged about 113,000 cfs; the maximum flows peaked at approximately 160,000 cfs. The Mississippi River stage reached its crest at 16.96 ft. on April 26. A slow fall is expected.
Bonnet Carré was first opened during the flood of 1937; since then it has operated eight other times during high water events in 1945, 1950, 1973, 1975, 1979, 1983, 1997 and now 2008.