An environmental mystery on Adams Bayou seems to on the way to a good conclusion.
Throughout the summer area boaters, anglers and other water recreationists have reported extremely high levels of duckweed and salvinia in the bayou.

Don Nation, 66, a member of the Orange Boating Club, has fished the area around the club headquarters off DuPont Drive all his life.

He grew up with his grandfather, Roy Delano, who worked for Shell Oil in Black’s Bayou. Nation lives in Little Cypress now but regularly returns to the DuPont waters.

“This is the worst I’ve ever seen it,” he said. “Duckweed looks pretty on the water but fishermen find it a nuisance. When it blooms it’s very pretty. It’s white, like snow on the water. I saw it do that on Caddo Lake once.”

Michael Hoke, director of Shangri La Botanical Gardens and Nature Center, has made Adams Bayou runs from Interstate 10 to Orange Lions City Park for 15 years, starting with his work with the Nature Classroom and later, Shangri La.

He also reports record levels of the weeds.

“Duckweed is the most common thing we have around here,” he said. “It’s almost impossible to get rid of. There are two different kinds of salvinia – the native form, which is bad – and the non-native form which is terrible. It can deprive any ecosystem of the ability to have oxygen in the water. Once it cuts out the oxygen, the whole ecosystem begins to fail. In Adams Bayou, the oxygen is so low anyway that a lot of the animals there have adapted to it.”

The growth increased in the early summer when there had been very little rain coupled with increasing hot temperatures.

“We have to look at what environmental conditions changed to make this happen,” he said. “It had to be – A: fertilizer or nutrients came from some source. It could have come from a golf course; or B: it could have been … where raw sewage leaked into the environment.”
Hoke said his theory is that “something got dumped in there.”

Fortunately, Hoke said, the growth appears to be subsiding because of recent heavy rains.
“It’s all but gone between the interstate and the city park,” he said.

The natural enemies of duckweed and salvinia are saltwater and, in the wintertime, hard freezes, Hoke said.

Residents with duckweed in their ponds often use rock salt to break it up, he said.