St. Tammany Parish’s coastline is dwindling, that’s no secret. But at what rate?

Longtime Madisonville Mayor Peter Gitz has watched Lake Pontchartrain devour large swaths of his seaside community’s coast over 30-plus years.

It wasn’t long ago, Gitz said, when the Tchefuncte River Lighthouse was accessible by vehicle via a road connecting the public boat launch to the lighthouse.

The marshland between Sunset Point and the Mandeville Lakefront is losing its battle with the lake. (Staff Photo by Chad Ruiz)

That road is gone now, and the lake has chewed away a huge chunk of land between the lighthouse and boat launch, making the lighthouse accessible by boat only.

To protect the lighthouse and boat launch areas, riffraff was installed along the shoreline.

“If the town wouldn’t have bought that land and secured it, it would all be washed away,” Gitz said.

Slidell and Mandeville also use riffraff, along with bulkheads, to secure much of their vulnerable coastlines.

But even with the preventative methods, Sunset Point in Mandeville and the lighthouse point in Madisonville continue to experience severe erosion every time a storm rolls through.

Mandeville Mayor Eddie Price said Sunset Point lost 10 to 15 feet of coastline thanks to hurricanes Gustav and Ike. Hurricane Katrina eroded more than 20 feet of land from the popular hangout and fishing spot, he said.

It’s a perpetual process, Price said.

Whenever land is lost, they refill it with more riffraff.

There’s worse news in Madisonville.

Louisiana Highway 1077, the only route to the boat launch, becomes inundated with water from the Tchefuncte River during strong southerly winds.

Gitz said the road is usually under water 100 days each year. For Gustav and Ike, he said the road was under water nearly six weeks straight.

The brackish water has taken its toll on the two-lane highway, leaving it riddled with large potholes and sections with layers peeled off.

The land separating the road from the Tchefuncte River has eroded away to nearly nothing.

And that’s nothing compared to the western shores of Lake Pontchartrain, where Carlton Dufrechou, director of the Lake Pontchartrain Basin Foundation, said the highest concentration of shoreline erosion is occurring.

Although St. Tammany’s coast has experienced its own share of erosion over the past several years thanks to Katrina, Gustav and Ike, it’s occurring at a slow rate, Dufrechou said.

That can be attributed to communities securing their coastlines using riffraff and bulkheads and other materials that serve to hinder the erosion process.

However, “armoring the coast can be positive and negative,” Dufrechou said.

When one area of a coastline is secured, the adjacent, unprotected coastline takes a harder hit from storm surges because the armoring material funnels the water into the bordering coastline.

Dufrechou said the cove being created between the lighthouse and boat launch in Madisonville is a result of the riffraff funneling the water into that unprotected area of land.

“While it does save the coast in that localized vicinity, it does aggravate the situation on either side,” Dufrechou said.

The same scenario is also taking place between Sunset Point and the Mandeville Lakefront, where Dufrechou said a segmented breakwater will likely be needed in the next several years.

Communities like Mandeville are making concerted efforts to fight the erosion problem.

Wetland assimilation projects, like the one set up in Mandeville, take treated sewerage and deposit it over depleted wetlands. The effluent acts as fertilizer that will help rejuvenate the marshes surrounding the city, ultimately creating an important buffer to protect against future storm surges.

But that will take some time to grow the needed marshes. Time many residents feel is not on their side.