Rare Florida Coastal Dune Lake Outflow

Big Redfish Lake is a rare coastal dune lake in the Florida panhandle. When we get heavy rains the lake will break open and flow into the Gulf of Mexico which creates vivid colors when the brackish brown lake water mixes with the clear blue Gulf waters. Walton County is home to 15 named coastal dune lakes along 26 miles of coastline. These lakes are a unique geographical feature and are only found in a few places in the world including Madagascar, Australia, New Zealand, Oregon, and here in Walton County. A coastal dune lake is defined as a shallow, irregularly shaped or elliptic depressions occurring in coastal communities that share an intermittent connection with the Gulf of Mexico through which freshwater and saltwater is exchanged. They are generally permanent water bodies, although water levels may fluctuate substantially. Typically identified as lentic water bodies without significant surface inflows or outflows. Instead, water is largely derived from lateral ground water seepage through the surrounding well-drained coastal sands. Storms occasionally provide large inputs of salt water and salinities vary dramatically over the long term. Our coastal dune lakes are even more unique because they share an intermittent connection with the Gulf of Mexico, referred to as an “outfall”, which aides in natural flood control allowing the lake water to pour into the Gulf as needed. The lake water is fed by streams, groundwater seepage, rain, and storm surge. Each lake's outfall and chemistry is different. Water conditions between lakes can vary greatly, from completely fresh to significantly saline.