Bob Warren / The Times-Picayune 25 June 2019

The poor quality of the water in Lake Pontchartain has prompted authorities on the North Shore to close beaches and the popular fishing pier near Slidell. The recent proliferation of algae in the water has also led state health officials to issue warnings to the public.

St. Tammany Parish government announced Tuesday morning (June 25) that Northshore Beach and the fishing pier will be closed until further notice. In Mandeville, the city put temporary fencing around a beach at Lakeshore and Jackson avenues.

“We hope it’s not for that long,” Mandeville Mayor Donald Villere said.

St. Tammany Parish government said the closures of Northshore Beach and the pier were prompted by an advisory June 21 from the state Department of Health urging people to avoid contact with lake water.

“The LDH is urging people to avoid contact with the water and the algae itself, but also advising against harvesting or eating fish from the lake during the bloom,” St. Tammany Parish President Pat Brister said. “We feel, out of an abundance of caution, it’s best to close these facilities until LDH advises that water is safe for human contact.”

In the advisory, the department warned of a potentially large algae bloom in the lake. It said the harmful algae is made up of cyanobacteria, which can produce a variety of toxins and can cause ailments ranging from rashes to diarrhea.

Previous algae blooms in the lake have been linked to openings of the Bonnet Carre Spillway along the Mississippi River. Spillway openings allow river water to flow into the lake, but that water can contain high levels of nutrients that cause algae blooms.

As of Monday, the Bonnet Carre Spillway had been open for 89 days so far in 2019, due to extraordinarily high water levels in the Mississippi.

John Lopez, director of coast and community programs for the Lake Pontchartrain Basin Foundation, said Tuesday the potential for “harmful” algae blooms in the lake should prompt caution among lake users. He added that the lake situation is “still unfolding.”

“It’s too early to say what the effects will be (of the spillway opening),” Lopez said, “but we certainly understand the need for caution.”

Meanwhile, along the Mississippi Gulf Coast a number of beaches have been closed due to concerns about water quality, Mississippi media outlets were reporting.

St. Tammany Parish government said signage indicating the closures of Northshore Beach, at the end of Carr Drive, and the fishing pier, which runs beneath the Interstate 10 twin span bridges, will be installed by the close of business Tuesday.

– With additional reporting from Diana Samuels.