2011 opening resulted in 30-percent mortality rate north of I-10, biologist says
Although deer season is currently closed now in the lower Atchafalaya Basin from Interstate 10 south to U.S. Highway 90 because of high water, word that the U.S. Army Corps of Engineers has ditched plans to open the Morganza Spillway for now is good news for the deer herd located there.
Scott Durham, a biologist director with the Louisiana Department of Wildlife and Fisheries, said while deer in the lower Basin have somewhat adjusted to life with high water, those north of I-10 in the spillway have not.
“In the lower Basin, this is more common. Flooding is usually later, but those deer have evolved and are adapted to getting out of there,” Durham said. “It doesn’t get this high that often, but flooding in the lower Atchafalaya is fairly constant. It’s a lower density deer herd to begin with, and they kind of know to get out. They get out way before it peaks — you can see them in adjacent ag land and people are more accustomed to it, and the deer are more accustomed to it.
“So other than maybe habitat stressors and a little increased harvest on adjacent land, you wouldn’t really see a profound impact on the lower end.”
But in May of 2011, when the Morganza Spillway was last opened, Durham said biologists estimated a 30-percent mortality rate for deer in the spillway north of Interstate 10.
“They’re not used to it. We had a much greater mortality on that end than we estimated on the lower end,” he said. “If they do open the Morganza, we request they open it slowly, but it kind of popped up 4 or 5 feet in an eight-hour period last time, and that kind of smacked them.
“They were swimming and getting on logs, so we definitely lost some adult deer. We didn’t see much mortality below I-10 because we think those deer are kind of used to it, and the water doesn’t come up quite as quickly there. But where it narrowed and the water pops up, the deer took a hit. But hopefully, we don’t think that’s going to happen this year.”
The operational trigger for the Morganza Spillway is when river levels reach 57 feet with a forecast flow of 1.5 million cubic feet per second and rising, according to a release from the Corps.
Current forecasts show the river will reach 57 feet at the structure on Friday (Jan. 15), but the projected peak flow rate will be only 1.44 million cfs on Sunday (Jan. 17) — not enough to warrant an opening.
Parts of the Area 9 deer season in Iberia, Iberville, St. Mary and St. Martin parishes were closed this weekend when the river reached 18 feet at the Butte La Rose gauge.
Deer hunting in those parts of the parishes between the Atchafalaya Basin guide levees south of Interstate 10 and north of U.S. Highway 90 will remain closed until the Atchafalaya River falls below the 18-foot mark, according to LDWF.
Current forecasts predict the Atchafalaya River will continue to rise until at least Jan. 17, at which time the National Weather Service expects the river to be at 19.7 feet at Butte La Rose. No predicted fall is shown on the available forecast.
