Flooding a swamp wildfire douses the flames, but boosts ‘noxious’ smoke

A “super fog” is blanketing the New Orleans area, worsening vehicle crashes and causing health concerns among residents. The weather phenomenon has been blamed for numerous traffic incidents including a series of horrific crashes in late October involving 158 vehicles that left seven people dead and 25 injured.

But attempts to douse a nearby wildfire may actually be making the super fog worse.

A 200-acre wildfire burning near the Bayou Sauvage Urban National Wildlife Refuge has been fully contained for weeks, but residents have told local media that “noxious smoke” from the fire is causing a harsh chemical-like odor. The uniquely foul-smelling smoke is caused, in part, by the fire’s underground burning.

Bayou Sauvage NWR
Bayou Sauvage NWR

“Your usual marsh fire is on dry brush and grass, and it burns fast and has a sweet smell,” the New Orleans Fire Department told the Times-Picayune. “But when it gets into that stuff underground, that’s rotting vegetation. And yes, it starts stinking.”

The stink may be gaining potency because of firefighters’ suppression efforts. They are working with the state Department of Agriculture and Forestry, the city’s Sewerage & Water Board, and the Army Corps of Engineers to drive drainage canal water to flood the swamp where the wildfire is burning.

The City of New Orleans’ Office of Homeland Security and Emergency Preparedness said the flooding is a last-ditch effort, with few other above-the-surface suppression efforts having any effect on extinguishing the fire. But, as more water is poured on the fire, more smoke rises.

“As you put water on some areas, you do experience more smoke coming up,” New Orleans Fire Department Superintendent Roman Nelson told the newspaper.

Vegetation in swamps and wetlands have a higher than average fuel moisture content, which requires more energy to drive off the water and increases emissions, i.e. smoke, per unit of fuel consumed, the FS Smoke Management Guide said. The last-resort flooding is, albeit temporarily, increasing the fuel moisture content and the noxious emissions.

Firefighters say it’s difficult to estimate just how much of the fire has been extinguished since the ground absorbs so much of the flooding, but they believe around 20 percent of the fire is now out.