Officials discuss flood's effects on Atchafalaya Basin
By: GEOFFREY STOUTE
MORGAN CITY — Fish kills, a washout of a portion of a Louisiana highway and waterways running in abnormal directions all were effects documented in the Atchafalaya Basin due to this spring’s flood.
During Monday’s public hearing in Morgan City to discuss proposed water quality projects, Basin program officials gave an update on the effects of the flood-fight, covering fisheries, wildlife, oil and gas, and recreation, among other topics.
The fish kills occurred in the Henderson Lake area and are believed to be caused by low dissolved oxygen, said Mike Walker, a biologist with the Louisiana Department of Wildlife and Fisheries and a member of the Basin Program’s Technical Advisory Group.
Walker said the event occurred here, as well as at Cow Island, because water backed up into nearby areas and covered vegetation. When the vegetation decayed, it depleted oxygen available for fish, resulting in the kills.
“This is probably the biggest flooding of Henderson (Lake) since they last opened Morganza,” Walker said.
Additionally, rainfall in the area also killed fish because it caused the oxygen levels in the water to flip, he said. While the areas of low oxygen were at the bottom of the water and the more plentiful areas were found in the surface water, a heavy downpour pushed the cold water and the good oxygen to the bottom and the bad oxygen to the surface, Walker said.
Since May, Walker has been taking water samples at 21 different sites in the Basin, twice a week.
Low dissolved oxygen levels have been noted in various areas of the Basin, including near the Old River Control Structure, where 30 percent of the Mississippi and the Red rivers are diverted down the Atchafalaya River.
Low oxygen levels were observed at Bayou Sorrel at both the Gulf Intracoastal Waterway and Bear Bayou, too.
As the summer has passed though, all of these areas have begun to improve, but until temperatures fall below 90 degrees, Walker expects these low oxygen levels to persist.
Crawfishermen also reported widespread low oxygen levels as well as loss of north/south flow that helps with water quality.
“The crawfish season really wasn’t as good as last year and last year’s season really wasn’t that good,” said Dave Fruge of the Basin Program.
The east side of the Basin fared better for crawfish than the western side.
Good dissolved oxygen sites were found in the GIWW and East Grand Lake, and the east and west side of Flat Lake.
Since the flood, however, sport fishing has returned as recreational anglers now pack boat launches on weekends.
However, water hyacinth problems have been found in upper Henderson Lake, while Pierre Part resident Phillip Daigle told the Basin board the same is occurring in some areas of Belle River that he said have limited access without such vessels as airboats.
Fruge said 400 acres are being treated and hundreds more will be treated.
Regarding wildlife, Fruge said that some black bears were lost or displaced and 30 percent of the deer herd between Interstate 10 and the Morganza Spillway structure also were lost. That, he said, means deer hunting in the Basin will be limited this year.
The Sherbourn Wildlife Management Area and the Atchafalaya National Wildlife Refuge also were closed during the flood. Sherbourn since has reopened and the Atchafalaya refuge, which suffered $187,000 in damages, is set to open soon.
Fruge said no lasting impact is expected to Basin forestry, though.
The Basin is also home to nearly 600 oil and gas producing wells. Of those 592 wells, at least 167 were shut off during the flood.
Fruge said there were fewer than 30 reports of spills, but only two spills involved more than a sheen — one with about two barrels and another with 10 barrels.
Despite the great loss of production, he said effects to refineries were minor.
Access roads to these oil and gas properties were damaged, too, while La. 975, a gravel road found in Iberville, Point Coupee and St. Martin parishes, was washed out.
Recreation in the Basin also did not escape harm as 40 of 260 to 300 structures in St. Martin Parish were damaged, while 187 of 328 camps in St. Mary Parish also were flooded.
The Belle River boat launch was among those recreation facilities that either flooded or was infiltrated with sediment carried by the bulging Atchafalaya.
Sediment buildup has been found elsewhere in the islands in the GIWW between Russo’s and Adams’ landings.
“That Intracoastal carried quite a sediment load,” Walker said.
Walker noted sediment deposits on the east side of Grand Lake, which is hindering him from accessing one of his sampling sites.
He warned people entering the Basin for the first time after the flood to be extremely cautious when traveling their normal routes.
“They’re liable to run into something that wasn’t there before,” Walker said.
Farm and pasture, and aquaculture areas were not spared damage, either, as 18,000 acres, mostly near the Morganza tailbay and forebay, were flooded.
Louisiana State University AgCenter specialists estimated the impact on agriculture from the Morganza opening at about $16 million.
Data collection of water quality for temperature, dissolved oxygen and turbidity have been taken as well as surface water grass samples to study the nutrient content. These efforts still are ongoing in the Basin with efforts from the Wildlife and Fisheries, the U.S. Geological Service, and other state and federal agencies as well as university researchers.
This data has been compiled into an interim report, and once finalized, will be put in final form and released to the public.