Although the Mississippi River is slowly receding, it remains above flood stage, and evidence of elevated water levels continues to seep through University grounds located just miles from the city’s levee structure. Damp parking lots and grassy areas surround the LSU School of Veterinary Medicine as water seeps through soil pores under the levee and into concrete cracks. The river crested at 43.13 feet this past Friday after reaching flood stage – 35 feet – March 30. The river dropped to 42.57 feet this past Tuesday and is expected to continue to fall slowly during the next several days. Excessive snow and heavy rainfall across the country this year contributed to the Mississippi River’s high water levels in April. And continual flow from the Missouri River and Ohio River Valley tributaries into the Mississippi River only increases the rising levels, said Patricia Brown, senior service hydrologist with NOAA National Weather Service. The rising river stirred concern with the University being situated at a lower elevation than the river’s height. But the University drainage system should be able to handle the excess water if it recedes gradually as expected, said Donald Adrian, civil and environmental engineering professor. “This flow and seepage is occurring right now, and it’s been happening for several weeks,” Adrian said. “Water seepage under levees and through ground pores is a natural process.” But Adrian said seepage could come up slowly through the floors of buildings near the levee. “It is not a desired condition, and it is something that may not have been foreseen when the buildings were constructed,” Adrian said. “If a building was designed during a dry period, where maybe several years went by without the water level getting very high, then it may be that it was not anticipated that there could be seepage.” Adrian said another concern arises with the formation of sand boils – a familiar site along sections of River Road bordering the levee. Boils form when certain conditions permit water seepage to become concentrated at a vulnerable point in the ground and flow at a rapid enough pace to erode soil. Several organizations including the U.S. Army Corps of Engineers, Louisiana Department of Transportation and Development and Pontchartrain Levee District are watching the dropping water level’s effects on the levee. The Pontchartrain Levee District conducts quarterly inspections on the 155-mile levee stretch it controls, but at least a dozen certified levee reporters have been giving daily reports since mid-March. Monica Salins, executive director of the Pontchartrain Levee District, said levee erosion, or sluffing, is not likely because of the water’s slow retreat. “We are getting with the [U.S. Army Corps of Engineers] to evaluate the concrete slope pavement,” Salins said. “I would worry more about sluffing if the water was receding at a faster rate. But because it is going down slowly, I don’t anticipate much erosion.” Salins said daily inspections will continue until engineers are comfortable with the river’s stage – a day that has several forecasters and engineers making predictions. The projected river stage by May 4 is 42.4 feet, according to the NOAA National Weather Service. And Salins said the Corps and Department of Public Works predict water levels to drop to 41 feet by May 9. Brown said the tributary contributions and the amount of rainfall are two main considerations in projecting when the river height will fall below flood stage. Until then, she said the water levels will continue to have adverse navigational and commerce impacts. “We haven’t had an incident like this in many years,” Brown said.
—-Contact Natalie Messina at [email protected]