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Sunday, July 14, 2019

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Grand Isle is sinking while standing water raises concerns

Grand Isle is sinking while standing water raises concerns

Standing water left in parts of Grand Isle after recent heavy rain and high tides has led to some concerns about the future of the island.

Capt. Danny Wray with Calmwater Charters submits reports and photos to the National Oceanic and Atmospheric Administration when he sees what he considers a weather anomaly or trend. Though he has no formal scientific training, what Wray has observed over the past years worries him.

For instance, between Sept. 13 and Sept. 14, the parking lot of Bridge Side Marina, 1618 La. 1, filled with water.

"We had a large volume of tidal fluctuation," Wray said. "It just pushes water back up on Grand Isle. If you drive down La. 1, the eastern side of La. 1 will fill up and the western side will drain. La. 1 acts like a low-lying dam."

Several local businesses reported experiencing rain and high tides, but not flooding.

Paula Jansen of Bridgeside Marina said she doesn't think the water at the marina was something for residents to be concerned about.

"On high tide, we do get higher waters at times," she said. "That was a little more than usual because it rained for like three hours, but the road wasn't closed."

Tim Osborn, regional navigation manager for NOAA, said this is part of a long-term natural process called deltaic abandonment, which began when the Mississippi River changed course.

It isn't a climate change issue, although that is always a concern, Osborn said.

"We've got people (saying), 'Are we going to have more severe rainstorms?' We're seeing that," he said. "These are the tell-tales or symptoms of a warming climate, but the predominant driver is ... over thousands of years, the Mississippi River has built up the coast. These delta areas are abandoned. There's a greatly reduced amount of sediment coming down the river today because of dams and better farming practices. You're seeing no new sediment being put into these areas."

A 2010 NOAA report said rising sea levels and sinking land could cause Grand Isle to flood as much as half a year by 2100. The report said between 2096 and 2100, sea level would rise by 2.7 feet.

In 2014, NOAA reported Grand Isle had lost 1.32 inches of elevation to the Gulf of Mexico within five years. The agency released graphs this month showing a sea-level rise of about 9.05 mm a year on Grand Isle.

Last week, NOAA's National Geodetic Survey began reviewing southeast Louisiana. Osborn said Friday that he hoped the team would get to Grand Isle soon.

South Lafourche Levee District General Manager Windell Curole said he often talks to Osborn and that NOAA's work has helped the Levee District accurately determine water and land elevations.

"If you're going to live in south Louisiana, you have to pay close attention to subsidence issues," Curole said. "We've seen that the bridge between Leeville and Golden Meadow has subsided one foot in 20 years. ... If you have a cake, the cake is subsidence and sea level rises to the icing. We're building the levees higher and are paying close attention to that."

Although the South Lafourche Levee District doesn't cover Grand Isle, the same concerns plague Curole's region and the island. This year, Curole said, the Larose floodgate has closed about 140 days.

Wray said he can't see the lost parts of Grand Isle being restored, although the island of about 1,400 people likely won't become uninhabitable in his lifetime.

"It really doesn't take more than three days of a southeast wind, and it starts to stack up on this side of the bay," he said. "It's foreshadowing of which direction we're headed."

Osborn said maintaining Louisiana's only populated barrier island is a matter of cost.

"Half of New Orleans today is below sea level, and yet New Orleans functions OK. But it's taken billions and billions of dollars to get it to be a viable community, and it's going to cost a ton of money in the future," he said. "What's the investment that needs to be made to protect Grand Isle and keep it a viable community, and are the state, the parish and Grand Isle willing to spend that money?"

-- Staff Writer Bridget Mire can be reached at 448-7639 or Follow her on Twitter @bridget_mire.