How would Bonnet Carre Spillway opening impact Pontchartrain fishing?

Salinities typically rebound in about six months, LPBF says

With Mississippi River levels continuing to rise, some expect the earliest-ever opening in the 85-year history of the Bonnet Carre Spillway — which would relieve pressure on the levees protecting New Orleans and divert freshwater into Lake Pontchartrain for the first time since 2011.

That has left anglers holding their collective breath, waiting to see if there will be any impact on the upcoming spring speckled trout fishing.

“It always shakes something up,” said Chas Champagne, creator of Matrix and Vortex Shad paddletail trout lures and owner of Dockside Guide Service on Lake Pontchartrain. “It will screw it up for a couple of months, but something usually comes out of it that you don’t see on a regular basis. When they opened it in 2011, it killed the trout fishing for a minute, but when it got right, it was pretty damn good for a while.

“But the bass fishing was phenomenal, and we had a monstrous flounder run in October of that year. So it’s going to hurt something, but something good usually comes from it.”

Dr. John Lopez, coastal program coordinator for the Lake Pontchartrain Basin Foundation, said he wasn’t aware of an official decision by the U.S. Army Corps of Engineers as of 3 p.m. today, but he suspects the spillway will open by this weekend or early next week.

“Right now, the best guess — and that’s really all this is — is this could be a relatively short-duration opening, maybe a little less than two weeks,” Lopez said. “But it only takes two weeks for the lake to be completely flush with river water.

“Assuming the opening is a typical-size opening of about 200,000 cubic feet per second, we’ll see much of the water displaced out and basically replaced by river water.”

The real impact on speckled trout and redfish this spring and summer probably won’t be known for several months, Lopez said. In May and June of 2011, when the spillway was last opened, normal salinities returned to the lake after about six months.

“So in terms of fishing, you had some effect on fall fishing, but in general with the openings it seems like you basically still get some of the fall run with trout and other fish in the lake,” Lopez said.

One of the side effects when fresh water is introduced into the Pontchartrain Basin is the possibility of potentially lethal algae blooms. But opening the spillway earlier rather than later could be beneficial in that regard, he said.

“There are lots of factors for algal blooms to occur,” Lopez said. “The water has to clear up and sediment has to fall out, so the water gets clearer and the lake denigrates so you have algal growth.

“The water temperature is also a factor, so it depends on the confluence of all those things. But I think in terms purely from the standpoint of the algal blooms, I think this makes it less likely we’ll have problems later in the year — but I don’t think it totally precludes the possibility.”

When the spillway last opened, Lopez said algal blooms weren’t a big problem. They were spotty for the spillway opening in 2008 and massive in 1997, when the lake was actually closed for a period of time because of the blooms, he said.

“The algal organisms aren’t all the same. Some are more beneficial than others,” he said. “Basically it does create food and feed the food chain, for the most part. But like anything, you can have too much of something.

“It can cause a severe condition with an excess, and some of the species of algae have a neurotoxin that can affect nervous systems of fish or even humans. So that’s where if you have a severe condition of certain types of these algae, you can have impacts to the ecosystem or to people.”

Timing-wise for Lake Pontchartrain fishing, Champagne thinks the earlier the spillway opens and closes, the better.

“I’d much rather them open it in January. We’re not doing much fishing right now anyway, so get it out of the way so by the time April gets here it’s run its course,” he said. “We hate when it opens in April because it shuts down our whole May and June run, which is almost our two biggest months out the year.”

For Champagne, who fishes mostly on the east side of the lake, potential flooding of the Pearl River is almost as big of a concern as opening the spillway. The last three years, freshwater from the Pearl has been pushed into the Pontchartrain Basin by east winds each spring.

“That’s where everything migrates from, so if you block off that main migration (route) from the Rigolets, the Pearl could be a much bigger problem than the spillway,” he said. “All the migratory species come from the east and the Gulf, so if the Pearl is flooded and shrimp and crustaceans sense that freshwater and don’t come in, it might be bigger problems than we feel with the spillway. If I knew I was going to get a real salty year with the Pearl staying low and all I had to do was deal with the opening of the spillway for two months, I’d take the spillway every time.

“Because the lake can be as salty as it wants — if the Pearl floods it, nothing is going to come in. You’re not going to get that brown shrimp season in the springtime, and that’s the key ingredient.”

Lopez agreed, saying the Pearl River is another unknown when dealing with a potential early spillway open.

“You don’t know initially what’s going to happen with the Pearl River,” Lopez said. “If we had the Bonnet Carre Spillway open and combine that with a very large Pearl River flood later in the spring, that’s going to prolong the recovery (in the lake) even further.

“But unless there’s a huge flood on the Pearl, we would expect the salinities to be rebounding around September or October — something like that.”

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Patrick Bonin
About Patrick Bonin 1316 Articles
Patrick Bonin is the former editor of Louisiana Sportsman magazine and

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