New water bunches fish

• By JOE MACALUSO
• Advocate Outdoors writer
• Published: Apr 13, 2008 - UPDATED: 12:05 a.m.

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Dudley Vandenborre and Hil Wegener remember the last time the Bonnet Carré Spillway was opened: 1997.

They must remember: Their families’ livelihoods depend on how they react to the introduction of Mississippi River floodwater into Lake Pontchartrain Basin, where they operate their charter fishing businesses.

During the summer, they will rely on the experience of working through past days when the spillway was opened to reduce stresses on Mississippi River levees between Baton Rouge and New Orleans.

“It’s not like somebody flipped a switch and everything changes all at once,” Vandenborre said. “Depending on how many bays they (the U.S. Corps of Engineers) open. If they open only 70, then we won’t see a lot of effect on the Northshore. And how long they keep the spillway open makes a difference, too.”

Wegener said freshwater, no matter the amount, affects the brackish-water balance in the lake and agrees with Vandenborre that Pontchartrain’s western and southern shorelines are the most-affected areas in the lake.

“It’s going to take a while, well, a few days, for the water to come through the lake,” Wegener said. “The gradual influx of (fresh) water will begin to move fish, and the last couple of times this has happens, we know as long as you stay ahead of the freshwater you can fish find.”

The fish
When Vandenborre and Wegener say “fish,” they mean speckled trout.

Using 1997 as a guide, Vandenborre said opening the spillway concentrates fish.

“We caught lots of fish in front of the (fresh) water. Yeah, we needed the wind to move just right, but we really caught fish,” he remembered.

Wegener didn’t have to consult his fishing logs to remember the spring and summer of 1997.

“Fishing along the Northshore was good, as long as you could find that clean saltwater. There were days when the (fresh) water and the wind jammed the fish next to the shoreline. There were trout all over the shoreline,” Wegener said.

The water
Mississippi River freshwater diverted through the Bonnet Carré comes through the western shoreline of Lake Pontchartrain. Hydrological pressure pushes the flow into the lake before the Earth’s rotation pulls the water southward.

After a week of flow — and depending on volume — it’s possible to see a dividing line between the muddy freshwater and the clearer brackish-to-saltwater in the state’s largest lake.