Diving into (and researching) the Wakulla Spring cave system

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For years, the Woodville Karst Plain Project had one mission: to explore the caves of the Wakulla Spring system. Wakulla Spring is one of the largest springs in North America, and its caves form the most extensive submerged system. The caves extend for about 25 miles, and mapping them is dangerous work. In this episode of Coast to Canopy, we talk to Chris Werner, Project Director for the WKPP, about this work, and the direction it is taking.

More recently, the mission has expanded to include more research. WKPP is conducting studies to determine the source of dark water in Wakulla Spring and to gain a better understanding of the connectivity of sinkholes and springs in the area. Their goal is to be a resource for the local government and community, hoping to guide decision-making regarding development around the most sensitive sections of the cave system.

The Woodville Karst Plain Project has also prioritized the visualization of these caves. They have plans to create a 3D map of the system, and have been recording videos of their dives. In them, you can see the dazzling rock formations, and both the tight passages and the wide open caves never before seen by human eyes. You can see a lot of that footage in the video above.

This is one of two posts I wrote for this episode. The other deals more specifically with the geology beneath our feet in the Woodville Karst Plain.

Meet our guest: Chris Werner

Dr. Christopher Werner is the Project Director of the Woodville Karst Plain Project. He received a bachelor’s degree in geology and planetary science from the University of Pittsburgh, with a minor in physics and math. He came to Florida because he wanted to dive in our area’s cave systems, and received his master’s in geology from Florida State University. After a career in the oil and gas industry, he returned to FSU to earn a Ph.D. in geophysical fluid dynamics. He has served as the Scientific Director of the Woodville Karst Plain Project since 1999.

Coast to Canopy blog posts are curated transcripts. My notes appear in italics.

Preparing to dive in to a cave

Chris Werner: It takes a lot of preparation. We spend a lot of time upfront planning some of the dives that we do. And we’re really standing on the shoulders of giants. You know, people that pioneered this when scuba kind of came into the into the fold as a technology, that in the 50s and 60s, people were kind of diving into the springs and some of the lakes in the area.

And they found these tremendous caves… But they were woefully unprepared, Rob. There was a heck of a lot of fatalities. And so over time, they adopted different equipment with redundancies built in, and they also adapted their techniques…

There’s training programs out there that give you that, but it’s also the experience, right? So you’ve got to build experience to be able to do that stuff. And within the Woodville Plain itself, it’s fairly unique. We’ve got shallow, extensive caves, run 60ft deep, 100ft deep, other portions of the cave systems, are 200, 210, and then places like Wakulla Cave itself have extensive sections that are 285 to 310 feet deep.

The toxic (and intoxicating) air of a deep cave dive

Chris Werner: Those are much, much more challenging because when you dive deeper, two of the problems you have is – one is the nitrogen and normal air that we breathe is 21% oxygen, 79% nitrogen… the deeper you go, the more narcotic [nitrogen] becomes. So you can’t really think…

They used to call it martini’s law when I was taking scuba diving in the 80s. Basically, every 33 ft, it’s like having another martini. You think about that and you’re like… Would I drive my car on four martinis? Probably not. Not a smart thing to do. Well, it’s the same thing in cave diving.

So, we’ve got that problem. The second problem you’ve got is the deeper you go, the oxygen becomes toxic to your body. Humans have grown up on the surface of the planet breathing air, but that [is] 21% oxygen. If you take that 300ft, you’re most likely going to have a convulsion, because it’s toxic to your body at that partial pressure.

What we do is we cut our mixes with helium for those deeper depths, and we’ve kept increasing that helium over time. When you dive deeper, you get past what’s called the recreational, no decompression limits. Then you’ve got to decompress before you can come to the surface.

It’s kind of the opposite of mountain climbers. Mountain climbers, they can’t just race up from wherever they start at base camp or the hiking trail. They’ve got to acclimatize. That acclimatization is essentially decompression, right? But we do it in the opposite order than mountaineers do it.

Minimizing the risk when exploring caves

Chris Werner: We put in a continuous guideline the whole way. We take surveys of that. We make notes of water flow, creatures that we see, potentially artifacts, potentially interesting geologic formations down there. Then, when we come back, we’ve got huge decompression obligations before we can surface. And so in some places, those aren’t too bad.

It’s a few hours in other places, depending on how long you stay at those deeper depths, you could be talking a ten, 12, 16, 20 plus hours of decompression. And so if you’re going to do something where your bottom time is two three for up to six hours, and you’re talking about decompression, that can be anywhere from ten, twelve, fourteen hours, all of a sudden you’re having to, plan for a 24 hour dive.

There’s a lot of things that we do and we’ve implemented over time to try and take out a lot of the risk, manage it in a way that we can get everybody in and out safely. That’s probably what we’re known for is our standards and our procedures, because they’ve been built up over a number of decades.

And and they keep us safe. And they allow us to repeat those dives over and over and over again safely.

What does it look like in a submerged cave?

Chris Werner: People always ask, well, what do you see down there?

But a lot of time it’s more about what you don’t see. The caves in the Woodville Karst Plain, and especially in Wakulla Cave, I mean, they can be really small passages where, basically just a human with maybe a couple tanks on can fit and not much more.

But they can also be these enormous passages that we refer to as Tallahassee Power Cave. And when you’ve got Tallahassee Power Cave, you’re talking widths anywhere from 60 to 100 feet wide, and you’re talking 40 to 60, sometimes 70 feet high. You can fly a jumbo jet through these things. They’re they’re that big.

And when the water is clear, your light can’t see the walls right? It’s that big. So you’re diving into an abyss. It’s a different world altogether. It’s almost a surreal experience.

You’re talking with a guy that’s been on the Woodville Karst Plain project for 30 years, right? So I’ve kind of gotten accustomed to that. But when you can break into some really new cave and it’s big and it’s going, and you just see a lot of different rock formations, the way the water has carved out the limestone… some of these things are really beautiful.

Sometimes you can see that contact between the Saint Mark’s Limestone and the Suwannee limestone (for more on formations, check out our other post for this episode). Sometimes you also see remnants of when sea level was much, much lower, where you’ll you’ll get a cross-section of a passage that we call a keyhole passage. So, you know, it’s it’s kind of spherical on top or, or an oval on top. And then it’s got like a small canyon cut out in the bottom of it.

Animals adapted to cave life

Chris Werner: The other thing we see down there is a lot is a lot of life. People wouldn’t imagine how much life is down there.

We always see catfish. They seem to go everywhere. We don’t know how far they’ll go from the light. I’ve not seen any albino catfish. Ever. However, there have been other places in Mexico and some other caves in Europe where they found albino fish, which means they haven’t been exposed to light in a really long time. And so they lose all the pigment in their in their skin, right?

But we find all the time, albino crayfish. There’s all kinds of amphipods and isopods. These are really small things that kind of float in the water column. All these places that you’ve got sinkholes or these karst windows or swallets that are taking some of these stream waters in, you’re getting everything that’s kind of in the forest or on the above ground going into that cave passage.

A lot of that stuff has nutrients. It’s got leaves and other things that these critters can eat. And that’s how they survive. So a lot of places we see stuff like that.

For more on the isopods and amphipods that live in caves, and the evolutionary processes that turn an animal swimming in surface waters into a blind, white cave animal, check out our story on a species discovery in the caves of Merritt’s Millpond.

Wakulla wildlife and the movement of water in the Woodville Karst Plain

The WKPP uses dye traces to determine the sources of water in Wakulla Spring. Once they had established those connections, they could see how the movement of water in the aquifer affected wildlife in and around the spring.

Chris Werner: A lot of times, you know, some of these passages may be too small for a human to fit through. But with dye it’s just going to go with water. So, we were tracing a lot of the the sinking streams, or swallets, in the area. And putting together how the aquifer functions dynamically was probably one of the most fulfilling things I had done in a while.

Worked on that for quite a few years with some colleagues at Florida Geologic Survey and colleagues at Florida State University, a whole bunch of great consultants… And so with those guys, we got a really good view that a lot of the things that we were seeing affecting not only the food web and the ecosystem, with it, the wildlife counts that were kind of changing. That was all being fed by the water. (You can tag along on a Wakulla Springs wildlife survey in this blog post)

If you understand the way that the water flows to some of these large springs, like Wakulla Springs, then you can understand what’s going on with the ecology and the food web and how that’s adapting to to changes. A lot of those changes, a lot of them are natural, but some of them are also human induced in at times.

It’s like a puzzle, that you’re trying to peel back the layers of the onion to get a fuller and fuller look, but yet you never have enough to completely figure it out.

Investigating the dark water at Wakulla Springs

Chris Werner: We, we know that, by a set of proxy data – when I talk about proxy data… we haven’t really measured the clarity of the water. What we’ve done is, the Park Service has tracked how many glass bottom boat days per year they can run. So, if it’s really, really dark, they’re not offering glass bottom boat tours because, well, you can’t see anything.

What we’ve seen since around the mid 90s, that has decreased precipitously, and probably over the past 5 or 6 years, it’s been basically, one or two days a year, sometimes no days per year. Which is telling me as a hydrologist that, essentially, what we have is we’ve got an unknown source of water coming into the Wakulla Springs basin somewhere.

And that is most likely, probably going to be some type of surface water or additional swamp that’s now draining in. And so I think the concept of drainage basins, what most people think about is surface water drainage basins. So, if I drop water on top of a mountain out west and it goes to the east, it’s going to flow down to the Mississippi eventually, if I put it in the where and the drop of water goes west, it’s going to pick up another river and it’s going to make its way to the Pacific Ocean somewhere.

In karst basins, it doesn’t work like that.

Water moving in three dimensions through overlapping basins

Chris Werner: You’ve got all these cave passages and these conduits going every single different way. Depending on how much rain you’ve got, or different hydraulic regimes that are going on inside the aquifer. Sometimes when you put water in one place, it’ll go to point A. The second time you do it, it goes to point B…

Well, what we see in karst basins is that the drainage basins overlap to some degree. And so, if there’s a lot of heavy rain in Tallahassee and… Leon Sinks system down to Wakulla Spring is just screaming…

If you’re adding additional water in a nearby basin that may not go to Wakulla, it may go someplace else. Say it goes to Spring Creek or goes to Wacissa springs or something like that… over to the Saint Marks River rise…

But if you haven’t had a lot of rain in Tallahassee and it’s really low hydraulic conditions, and all of a sudden over parts of the Saint Marks River rise basin, you get tremendous amounts of rainfall. All of a sudden it can’t all come out at the river rise. And so that overflows into the Wakulla Basin, and would essentially flow to the Wakulla River somewhere or to… either Wakulla Spring itself or something like McBride Springs or some of the other springs that we know along the river.

So you get these really complicated kind of feedback loops. I think the biggest challenge we’ve got is that we’re monitoring quite a few places, but we’re not monitoring enough that we can tell exactly what hydraulic conditions would influence something else. As far as the dark water in Wakulla goes, my personal view is we’re missing a source of water somewhere.

Now, I don’t have a lot of evidence for that just yet. However, we were working with Florida State University Coastal Marine Lab on a project, and we’re still waiting for some data to come back. My guess is that’s probably going to show that we’ve got a source of water that we previously didn’t account for.

Is saltwater reaching Wakulla Spring?

Chris Werner: One of the things besides the dark water, the other kind of mystery that we had with Wakulla Springs was these high conductance events (in other words, the water could more easily conduct electricity)…

Over the past, let’s call it 18 or 19 years, we’ve seen 14 of those on record… And we’re trying to figure out, okay, what is that? Some people had the hypothesis, some FSU researchers in the past, as well as the USGS, that that maybe you had water from Spring Creek at the coast that was working its way up the conduit system and getting expelled at it Wakulla Spring.

I had my doubts about that. We’re still trying to figure that out.

The Woodville Karst Plain Project is using isotope data to chemically match the water in Wakulla Spring to potential surface water sources.

Chris Werner: That’s what we’re waiting on some of the final isotope data to tell us. But we should know that relatively soon once we get that back from the laboratories. I think that’s going to it’s going to tell us definitively whether that’s true or not.

So some people have made the jump from the conductivity to this has got to be saltwater, saltwater or seawater from the Gulf. And that’s the part where maybe you’ve got one variable you’re looking at. That may not be it. Because there’s… some streams and some some swamps where, depending on the exposed rock you’ve got and how long of a residence time that water has in that swamp, I can show you high conductivity waters coming in.

Further Floridan Aquifer reading and viewing

Springs and caves are just a couple of features that let us glimpse the larger Floridan Aquifer. The aquifer provides drinking water to much of Florida, and parts of Georgia. It is the source of 33 first-magnitude springs in Florida, and countless other smaller springs. Our area also has sinkhole lakes, disappearing/ reappearing rivers, and ephemeral wetlands that rise and fall with the fullness of the upper aquifer.

The Florida panhandle is a prime place to observe how surface water becomes groundwater, and vice versa. The following are a few of our karst adventures:

• Hiking the Aucilla Sinks with Florida State Geologist Harley Means (he was, at the time, assistant State Geologist).
• Hiking to Lake Miccosukee sinkholes with Harley Means.
• Lake Jackson dry down in 2021.
• Cave crustacean species discovered in Merritt’s Mill Pond spring caves.
• Wakulla Springs wildlife surveys.