Don’t Panic, It’s Just Tannic: How the Coastal Dune Lakes Get Their Color

The outfall of Western Lake, the coastal dune lake found within Grayton Beach State Park. Photo by Nic Stoltzfus.

By Sarah Hanley

Coastal Dune Tea, Anyone?

The South loves to drink sweet tea by the gallon, of that there is no question. However, when people stop to enjoy the serene beauty of our rare coastal dune lakes for the first time, the lakes often look like they’ve been made from copper-colored sweet tea. The first thought on everyone’s mind is inevitably, “Eww! Polluted!”

We’re here to set your fears to rest. The 15 coastal dune lakes that run the entire length of the 30A corridor are NOT polluted. That isn’t smelly waste water that laps the shores of these rare beauties. It’s nothing more than tannic water.

Don’t Panic, It’s Just Tannic

Tannic water is created when leaves, grasses, pine needles, and other organic matter falls into the water. The matter breaks down over time, giving the water that tea-stained look.

Oyster Lake outfall. Photo by Elam Stolzfus
Oyster Lake outfall. Photo by Elam Stoltzfus

In fact, almost all lakes and rivers contain some form of tannic water. But here on 30A, the crystal clear green waters of the Gulf make the contrast with the tea-colored lakes all the more stark. It is common for people to make the mistake of thinking the water is “dirty” and maybe even harmful, especially when the lakes break open into the Gulf.

That’s far from true, said Elam Stoltzfus, producer of the new documentary Coastal Dune Lakes: Jewels of Florida’s Emerald Coast. “Tannic water isn’t harmful, in fact, if you look closely at the water in the lakes, it’s very clear. The unique color comes mainly from the pine trees that surround the lakes.”

Another misconception, this one by many locals, is that brackish water is what creates the brown color. Brackish water is a mixture of saltwater and freshwater, and while most of the coastal dune lakes are brackish, that’s not what gives the lakes their color, Stoltzfus added.

How Did We Get Clear?

Each lake is highly dynamic, so when one lake looks like a tea bag has been brewing in it for weeks, another may be crystal clear.  During the rare times when water from the Gulf actually breaks up and flows into the lake, the lake water becomes more clear as it’s filled with those emerald Gulf waters.

Here’s to our unique and rare beauties, our 15 coastal dune lakes. Clear or tea stained, they are a source of pride for everyone along 30A and something we all strive to protect and preserve for generations to come.

Check out these videos for more information:

To learn more about the lakes and the new documentary, check out coastaldunelakes.org.

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