Coastal Information Management System

Whiskey Island Back Barrier Marsh Creation

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Project Location

Whiskey Island, one of five islands that make up the Isles Dernieres barrier island chain, is located 18 miles southwest of Cocodrie in Terrebonne Parish, Louisiana. The island is surrounded by Coupe Colin to the west, Whiskey Pass to the east, Lake Pelto, Caillou Boca, and Caillou Bay to the north, and the Gulf of Mexico to the south.

Project Description

This project involved construction of 316 acres of back barrier marsh on Whiskey Island in Terrebonne Parish using 2.5 million cubic yards of sediment dredged from the Gulf of Mexico. Other project features include 5,800 linear feet of tidal creeks, three one-acre tidal ponds, and 13,000 linear feet of sand dune on the gulf side beach shore.

Issue Addressed

Gulfside and bayside erosion has resulted in the narrowing of Whiskey Island (and the entire Isles Dernieres chain) as the two shorelines migrate toward each other, resulting in a 68 percent decrease in average width for the Isles Dernieres. Within 100 years, the entire subaerial portion of the Isles Dernieres barrier island system is expected to disappear except for small land fragments associated with the western end of Whiskey Island and the eastern end of East Island. However, some estimates project the Isles Dernieres will disappear much earlier. Other predictions suggest that, without restoration, Whiskey Island could become a subaqueous sand shoal by 2019.

Project Goals

The goal of the TE-50 project is to increase the longevity of the previously restored and natural portions of the island by increasing the island's width. Increasing the island's width will help to retain sand volume and elevation. Approximately 319 acres of back barrier intertidal marsh habitat, 5,865 linear feet of tidal creeks, three 1-acre tidal ponds and 13,000 linear feet of protective sand dune were created by semiconfined disposal and placement of dredged material. The sediment was dredged from a sediment source in the Gulf of Mexico near the island. The area was planted with native marsh vegetation to colonize and protect the newlyplaced marsh soil.