From Walton Sun
South Walton’s lakes are so rare that they are considered globally imperiled by the Florida Natural Areas Inventory. Throughout the world, the only known locations of other coastal dune lakes are in New Zealand, Australia and Madagascar, and scattered among the Gulf Coast of the United States. With 15 coastal dunes lakes, Walton County has the highest concentration of coastal dune lakes in the world. Topsail Hill Preserve State Park has three major coastal dune lakes, including Morris, Campbell, Stalworth and two minor unnamed lakes encompassing more than 170 acres of these freshwater lakes.
Coastal dune lakes are unique from other lakes or lagoons due to their intermittent connection to the Gulf of Mexico. Coastal dune lakes may form in many way including by wind activity in arid regions where wind erodes rock or redistribute the sand. In the Gulf Coast of the U.S. coastal dune lakes were most probably relic lagoons that have been shaped by the erosional forces of wind and waves. These same forces are still affecting the lakes today.
Coastal dune lakes within Topsail Hill Preserve State Park are separated from the Gulf of Mexico by sands that form beach and dune systems. Freshwater seeps laterally into the lakes through the sand. When these lakes reach their maximum capacity of freshwater, due to rain and groundwater seepage, the weakest area of sand around the bank separates the lake from the gulf. The “blow out” creates an outfall connecting the lakes to the gulf. This outfall will fill with sand at various rates of time plugging the outfall. This dynamic process that opens and closes the outfall creating its intermittent connection to the gulf is unique to coastal dune lakes. Some coastal dune lakes are connected to the gulf through their outfall for long periods of time and outfalls of other lakes rarely open. The amount of saltwater in coastal dune lakes varies from lake to lake depending on how long its outfall is open to the gulf. Another significant source of saltwater in coastal dune lakes is from storms that push saltwater into the lakes through the outfall or overwash from dunes.
Dune lakes provide habitat and forage for a diversity of plants and animals that range from fresh, estuarine, to marine. This allows several different types of plants and animals to use this environment. While the outfall is open and freshwater is being released from the lake, tidal water and marine organisms enter the lake. Migratory birds rely on the coastal dune lakes within Topsail Hill Preserve State Park as a refuge along an arduous journey along their route. The lakes and the habitats around them including maritime hammocks are used heavily by neo-tropical birds as stopover sites for resting, feeding, and cover during spring and fall migrations. While walking along the lake, you may find wading birds foraging such as beautiful egrets, or birds of prey such as ospreys and hawks.
One of the lakes at Topsail Hill Preserve State Park, Campbell Lake is worth the hike to view it. Not only is it scenic and a good example of a coastal dune lake, it is also an unusual lake because its outfall rarely opens into the ocean and remains virtually untouched by outside influences.
Monitoring and maintenance of the water quality and natural vegetation buffers around the lakes are of great concern to Topsail Hill Preserve State Park. Trained volunteers with Choctawhatchee Basin Alliance’s Coastal Dune Lake Program take pride in monitoring these important lakes. The Coastal Dune Lake Program is a team effort in which volunteers work with CBA’s Program Coordinator, Phillip Ellis and researchers at the University of Florida’s Lakewatch Program to collect basic information and contribute to the understanding of Florida’s lakes.
For more information on CBA volunteering or supporting Lakewatch in your community, contact Phillip Ellis at (850) 650-9330 or
cdlakes@owcc.net.
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