N.O. East has seldom flooded since Katrina
14th August 2017 · 0 Comments
By Susan Buchanan
Contributing Writer
In the 1960s and later, developers built man-made lakes or retention ponds in residential communities in New Orleans East, which had been reclaimed from cypress swamps. Aside from light flooding during Hurricane Betsy in 1965 and a Katrina-related deluge from the Mississippi River-Gulf Outlet Canal in 2005, streets in the East hardly flood. That surprises naysayers who feel that this swathe of the Ninth Ward was overdeveloped and should be returned to wetlands.
“The East’s man-made lakes act as buffer tanks,” Nicholas Mannix, an engineering manager with Woodward Design+Build in New Orleans, said last week. “Water hitting hard surfaces, like roofs or pavement, can run off into a retention pond or lake, where it’s captured for eventual entry into the municipal system.” The rainwater is released as a controlled discharge to prevent flooding. Regulations for building these lakes are outlined in the city’s Comprehensive Zoning Ordinance, he said.
New Orleans East developer Wade Verges said subdivisions in the East typically have one man-made lake each. These lakes have overflow lines to canals, principally the Morrison Canal, which connects to pump stations. The water is then pumped into Lake Pontchartrain, and because of this engineering, the area’s man-made lakes don’t overflow, he said.
Stephen Nelson, a Tulane University environmental sciences professor, said that subsidence or sinking has increased throughout New Orleans as groundwater pumping accelerated in recent decades. Man-made lakes in New Orleans East make sense since they slow the removal of water, leaving soil material behind and dampening the rate of subsidence.
Verges said unlike other parts of the city, streets in the East almost never flood. They did take on water around the Morrison Canal during Betsy in 1965. But after that, little flooding occurred until Katrina, when storm surge from the Industrial Canal inundated the Lower Ninth Ward and New Orleans East. To prevent similar catastrophes, the U.S. Army Corps of Engineers closed the MR-GO in 2009.
Verges recalls when the first lakes were built in New Orleans East. Lake Kenilworth was one of the earliest subdivisions. Soil from digging the lakes was taken to Interstate-10 construction sites for use there, he said. The completion of I-10 in the mid-1960s allowed rapid, suburban-style development in the East. When he lived in a subdivision there, Verges said he appreciated the beauty of its lake, and his kids enjoyed splashing in it.
Verges said a plan to shrink the city’s footprint, proposed by the Washington, D.C.-based Urban Land Institute and others in late 2005, didn’t fly. At the time, New Orleans East and the Lower Ninth Ward were seen as areas that could be returned to nature for wetlands reclamation. The city’s population was on the decline before Katrina, planners noted. “But Black people, who were the main residents of the East and the Lower Ninth, feared something was about to be taken from them,” Verges said. “They didn’t support the proposal and it died.”
A few spots in New Orleans East, Lakeview south of Robert E. Lee Boulevard, and Gentilly are well below sea level, and appear as red-hot spots on topographic maps, said Ioannis Georgiou, University of New Orleans associate professor and director of the Pontchartrain Institute for Environmental Sciences. At 10 to 15 feet below sea level, they contrast with the city’s sliver above sea level along the Mississippi River. But the lowest spots in Orleans Parish are safer today, following work done by the Army Corps in the dozen years since Katrina, Georgiou said.
By early 2014, the Army Corps had completed most of the $14.5 billion New Orleans Hurricane and Storm Damage Risk Reduction System or HSDRRS, with over 130 miles of levees, flood walls, gated structures and pump stations. At that time, FEMA “certified” the levees as having reduced risks from a potential, 100-year storm in Orleans and surrounding parishes. Because of the project, surge barriers at Lake Borgne, Seabrook, the New Orleans Outfall Canals and West Closure Complex now defend the city’s interior levees and flood walls. Efforts to protect the city have continued under the Southeast Louisiana Urban Flood Damage Reduction Project or SELA.
“But we won’t really know just how robust this protection is until the system is put to the test,” Georgiou said. Isaac, a category one hurricane in late August 2012, left city residents without power for days, but did little damage. In early October 2013, Tropical Storm Karen looked menacing, but fizzled in the northern Gulf.
While Mid City and other parts of town flooded this August 6 and in late July, the East was spared. In a growing Sewerage and Water Board of New Orleans crisis last week, only 65 percent of the city’s pumps west of the Industrial Canal were active, and out of five turbines, one was newly damaged and another three were offline and awaiting repairs. All of the city west of the Industrial Canal was at risk for flooding, but New Orleans East, the Lower Nine and Algiers—operating on a separate power source—weren’t under threat, Mayor Mitch Landrieu said.
That’s not to say New Orleans East isn’t vulnerable to extreme weather. In early February, more than 250 homes and businesses on and near Chef Menteur Highway were instantly damaged or destroyed by a tornado.
As for the area’s man-made lakes, retention is still fairly novel in the Crescent City, but American farmers for centuries have built ponds for irrigation, soil conservation and livestock watering. Ancient Romans used retention ponds to slow runoff, and early civilizations in China, Egypt and Mesopotamia used them for flood control, agriculture and aquaculture.
This article originally published in the August 14, 2017 print edition of The Louisiana Weekly newspaper.
