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Restoring Coastal Waters

Posted on Aug 28, 2019 in Invasive grass , Big Redfish Lake , September–October 2019 , The Choctawhatchee Basin Alliance

Before (above) and after (below) photos show the invasive grass removal at Big Redfish Lake. Photos by Rachel Gwin

Invasive grass removal at Big Redfish Lake by Erika Zambello

The Choctawhatchee Basin Alliance (CBA) restoration team and AmeriCorps Northwest Florida (NWF) Environmental Stewards arrive at Big Redfish Lake early in the morning, gloves and wading boots on. Their goal for the day is simple: remove as much of the tall, swaying phragmites grasses from the shoreline as possible.

Walton County hosts 15 named coastal dune lakes, rare water formations within two miles of the Gulf of Mexico, which periodically break through the sand dune barrier to exchange currents with the Gulf. As a result, the water within coastal dune lakes is brackish — a mix of salt and fresh — and creates unique plant and animal communities. In fact, coastal dune lakes are found in only a handful of locations across the world, including Madagascar, Australia, the Carolinas and Oregon.

Each of Walton County’s coastal dune lakes has its own character, based on the combination of its size, watershed features, surrounding land uses, and outlet characteristics. Outlet openings vary greatly in length, frequency and duration. They are driven by each lake’s critical high-water level as well as prevailing climatic conditions (e.g., droughts and rain). As a result, some of the dune lakes can be completely freshwater, some brackish, and some salty, with varying degrees of salinity occurring between different lake stages. The changing condition of water chemistry in the coastal dune lakes makes them dynamic, biologically diverse ecosystems.

While coastal dune lakes are natural resource gems, they are also susceptible to invasive plants that outcompete the native species the ecosystem needs to thrive. Phragmites grows so tall and dense that it’s nearly impossible for other grass varieties to displace them; moreover, their thick roots and stems disrupt important water flow points within the lakes themselves.

Restoring Coastal Waters

To combat this and other invasive grass species, CBA is leading a new initiative to remove as much of the phragmites and invasive grasses as possible in multiple dune lakes around Walton County. The work itself is difficult, involving long, hot hours by the water’s edge pulling up the grasses when possible and cutting down stalks with mechanized trimmers. While they could reach the Big Redfish shoreline on foot, to work on other locations they must kayak to their invasive removal sites.

“Restoring habitat within our watershed is one of CBA’s core goals,” explains Alison McDowell, director of CBA. “In addition to building reef breakwaters and living shorelines, we also work with landowners in and around the coastal dune lakes to remove invasive vegetation. The native grasses that return provide more ideal habitat for the wildlife we love so much.”

Unfortunately, it’s nearly impossible to keep phragmites out of coastal dune lakes forever. Through regular maintenance removals — such as the one completed on Redfish Lake — CBA can keep the lakes as natural as possible.

By the end of the afternoon, the CBA and AmeriCorps team had unearthed the original Redfish Lake shoreline, ready for new grasses to create a green, living, resilient border.