Texas river cooters
Autumn on the San Marcos River, and with the summer tourists gone, I have the place to myself. This time of year, the cedar elms and bald cypress, two of the most common trees that grow here, turn from green to gold and red. Less showy, bur oaks and sycamores will add a smattering of yellow brown to the canvas before dusting the surface of the water with their leaves. I like this season not just for its color, but also for the way the light comes through the trees, angling into the river, playing on the undulating wild rice.
I’ve been snorkeling in this river for sixteen years now and documenting a small stretch of it for about thirteen. Once a week, year ‘round, regardless of the weather, I will swim for several hours, picking up trash as I go, but mostly photographing what I find—fish and turtles, plants and rocks, even the contours of the riverbed, which change depending on the flow. Based on John Burroughs’ maxim—“To learn something new, take the path that you took yesterday”—I decided a long time ago to focus on the half-mile reach that runs from City Park, through Sewell Park, and on to the spillway below Spring Lake.
Like all Texas Hill Country rivers, the first several miles of the San Marcos are swift, clear, and not very deep. Some 200 springs, the second largest collection in the state, percolate from the Edwards Aquifer to create this 75-mile-long watercourse. Dammed in 1849 to power a grist mill and sawmill, its headwaters, roughly a half mile away from the park, are now buried beneath Spring Lake. Before that time, when the river meandered, spreading its waters across sand and clay at the base of the Balcones Escarpment, Clovis people camped here. Their artifacts—projectile points and chipping debris, along with remnants of mastodon and bison—still emerge from time to time.
Spotted gar
I came to the San Marcos late, later than the children who grew up swimming here on summer afternoons, who rode their tubes on the current or played fetch with their impatient dogs. Indeed, it was my own dog, a tubby chocolate Lab, whom I credit with bringing me here. She was overweight, the vet had pronounced, and she needed to lose some pounds. Swimming would be just the thing.
And so that summer, sixteen years ago, we went to the river each day. Right after lunch, I would change into my swimsuit—I had no wetsuit at the time—put the dog in her harness, and head off to town. I’d inch my way down the rocky bank, trying to hang on to the dog, and wade in as far as a boulder where the two of us could sit before starting our game of fetch. The water was up to my waist that year, well over the Lab’s head.
Kids and dogs, college students and families on vacation—it was a busy summer at the river, which runs through the middle of our town. Behind us, children played in shallow water, pulling white clay from the 10-foot cut bank and using it to paint themselves or fling at one another. Nearby, in an area known as Dog Beach, the water was even more shallow and slow, which made it conducive to snorkeling. Kids, especially, enjoyed hunting for swimmers’ lost jewelry or coins, arrowheads, and other relics. Occasionally, they’d find something, but usually they’d come up with pull tabs from soft drink cans or the occasional piece of glass.
These pint-sized snorkelers intrigued me. I had never wanted to do so before, but I suddenly ached to join them, plunging my face underwater and seeing whatever they saw. If they could do this, I reasoned, so could I. And thus began my love of the San Marcos River.
Native American stone artifact
Like the children I witnessed snorkeling all those years ago, I seldom find anything of monetary value in the river. Occasionally, though, I’ll come across something of worth—a driver’s license, a credit card, a cell phone. Discovering items like these is exciting, in part because of the detective work required to get them back to their owners. Discovering a stone artifact, such as the scraper I found protruding from the gravel in Sewell Park, is even more of a thrill.
Just how old these artifacts are was a mystery until the late 1970s, when two decades of intermittent excavation in Spring Lake resulted in a rich but mixed collection of spear points and other tools from multiple time periods. Reports from the earliest work, done by Dr. Joel Shiner of Southern Methodist University, were not well received by the archeology community. The historical timeline of the deposits was impossible to determine due to the presence of loose gravel, sharp-edged stones and larger rocks that had tumbled down from the cliffs above and the artifacts’ proximity to the original stream. In short, the layers were co-mingled, resulting in a mishmash of objects, some dating to prehistoric times and some from the modern era.
Nonetheless, Shiner’s discoveries were invaluable in establishing the importance of the San Marcos Springs in early human history. Given that the artifacts he collected represent every archeological period for which evidence has been found in Central Texas, researchers believe that continuous settlements at the springs date back for millennia. This fact, says Dr. Jon Lohse, “has provided the basis for the anecdotal description of Spring Lake as the longest continuously occupied site in North America.” He admits that such a claim eludes scientific proof, but “with an occupation spanning more than 13,000 years, from Clovis times all the way through the prehistoric sequence to the Spanish Colonial era and into the Historic period, Spring Lake certainly contains one of the longest, if not the longest, continuous cultural sequence in Texas and perhaps beyond.”
Redspotted sunfish (left) and redbreast sunfish (right)
The metal grid marking Shiner’s excavation site is still visible to visitors touring the lake today. Cruising in glass-bottom boats, they can look down to a depth of 30-40 feet, where they’ll find not only the last evidence of his work, but also white patches marking the largest springs in the lake. Most of these, like Cream of Wheat Spring and Salt and Pepper Spring, are sand boils, bubbling up fine sediments, sand and silt, gravel, and sometimes larger rocks. Frequently, sunfish and largemouth bass will collect around these boils, waiting for invertebrates to appear.
These springs, along with Shiner’s archeological ruins, figure prominently in the narration of every boat tour guide who explains the natural and historic features of Spring Lake, among them a petrified tree that remains near the original riverbed as evidence of an earthquake that occurred 20-25 million years ago. Indeed, it was a series of quakes like this that created the fault line running through Central Texas, and with it, the Balcones Escarpment. The San Marcos Springs emerge from three large fissures in this rock.
Visitors to the lake will also hear about the glass-bottom boats themselves, some of which date to the 1940s. These are the last remnant of the amusement park that occupied this site for decades, a place known as Aquarena Springs.
Red swamp crayfish (left) and largemouth bass (right)
Development on the lake began in 1929 with the opening of Rogers Spring Lake Park Hotel, a two-story art deco structure that featured nearly three dozen guest rooms, a golf shop, a café, and a rooftop designed for dancing. In the late ’40s and early ’50s, the Rogers’ added glass bottom boats, a submarine theater with swimming Aquamaids who ate and drank underwater, a nine-hole golf course, a gondola ride, an Old West town, and even a tic-tac-toe-playing chicken and a series of diving pigs, all named “Ralph.” As quaint as this sounds today, Aquarena was Texas’ top commercial tourist destination in the 1950s. By the 1990s, however, everything had changed.
With the advent of theme parks that offered hair-raising rides, Aquarena’s popularity waned, so much so that in 1994, it was purchased by neighboring Texas State University, to be used as a site for research and conservation. One by one, the theme park’s features were removed, until all that remains today are the boats and the old hotel, now home to the university’s Meadows Center for Water and the Environment. These days, admission to the waters of Spring Lake is by special permission only, thanks to the Texas blind salamander, fountain darter, and six other federally protected species that live in the springs and the river beyond.
Visitors can now follow a trail that winds along the lake, meandering under bald cypress trees and through a meadow. Eventually, they will come to a boardwalk that stretches across a shallow slough. Depending on the season and time of day, they may see a large selection of water birds—including great blue herons, little blue herons, great egrets, cormorants, greater yellow-legs, green and yellow-crowned night herons, pied billed grebes and coots, various ducks, and soras—as well as osprey, belted kingfishers, red-shouldered hawks, and black vultures. A beaver lodge currently sits to one side of the walkway, and turtles—red-eared sliders and river cooters—are almost always found basking on logs and rocks in the slough.
Texas river cooter
One unwanted resident of the slough is the non-native blue tilapia, the males of which create dish-shaped nests in the silt to attract females. When competition for mates and space is high, the males battle, body-slamming one another and splashing in the shallow water. No one knows exactly how these African fish ended up in Spring Lake, as well as in the river, but the theory is that they were introduced for sport fishing. Weighing up to six pounds, they vie with native species for food and spawning grounds. Consequently, they, along with the invasive plecostomus (armored or suckermouth catfish) are the target of a year ‘round program that removes them through spear fishing. Between 2013 and 2022, over 6,500 pounds of tilapia were extracted from Spring Lake, with another thousand or more culled from the river. During that same time, 6,500 pounds of plecostomus were taken from the Upper San Marcos, including Spring Lake.
Stranger, perhaps, has been the removal of an even more unnatural “inhabitant” of the lake: thousands and thousands of golf balls, remnants of the area’s past life. After a devastating 2015 storm, decades’ worth of errant golf balls were washed out of the slough—the course’s sometime water hazard—and into the lake and river. For several years now, crews from the Meadows Center, along with volunteers, have been collecting these golf balls from the shallow water just above the dam. At last count, they’re retrieved more than 20,000.
I have been part of this effort on several occasions, and have also removed a good number of golf balls from the Upper San Marcos, including a heavy trove I collected immediately after the flood. Even today, balls continue to surface, along with old bottles, broken glass, and beer cans flattened by years of being buried in the sand. From time to time, I come upon rusty bolts, nails, and other detritus from the riverside mills. If I’m lucky, I’ll go home with a spear point or, more often, a partially worked stone or stone chips.
Texas wild rice and pennywort
This fall, as I pull on my wetsuit and prepare to dive into the San Marcos, I notice that after a summer of abuse from tubers and swimmers and, worst of all, people walking in the river, the vegetation is making a comeback. Worn down in places, Illinois pondweed is returning to the marsh upstream from City Park. Crews from the Meadows Center have been out removing invasive species—water lettuce, water sprite, hydrilla, and hygrophila, the latter two introduced by the aquarium trade. In their place they’re planting natives such as grassy arrowhead, water primrose, and Texas wild rice. Removing the invasive species also makes room for native plants to thrive, including pennywort, a plant with bright green leaves about the size of a half-dollar; the frilly fanwort or cabomba, which has the delightful habit of bearing white flowers underwater; and water stargrass, a delicate-looking plant that puts on yellow blooms just above the surface. All of these provide food and shelter for any number of micro and macro invertebrates, as well as turtles and fish.
Learning to identify these plants wasn’t easy, so I began sixteen years ago with the most obvious, the endangered Texas wild rice. Most places in the river, its 1- to 2-meter-long stems stay underwater, flowing like ribbons in the current, magical to watch. In more shallow spots, particularly between Sewell and City Parks, as well as just below the dam, it breaks the surface, producing flowers and seeds that are sometimes collected for propagation. Though this rice is technically edible, its main function is to serve as habitat for the endangered fountain darter and other small aquatic life.
While snorkeling, I occasionally see wildlife biologists out seining to check populations of these elusive inch-long fish. What I’m much more likely to see myself are the somewhat larger Guadalupe darters, which reach a length of about three inches. Though they’re well camouflaged by their olive and black coloring, I regularly spot them, usually lying on gravel in fast, shallow water, perched on leaves of wild rice, or literally “darting” across the river bottom. What makes darters so unusual is the fact that they have no swim bladders, and thus cannot swim. Instead, they move in short bursts, making them hard to see and even harder to photograph. Sometimes I get lucky, though.
Guadalupe darter
What I have much more success photographing are the larger fish in the river—redear sunfish, redbreast sunfish, bluegill, Rio Grande cichlid, largemouth bass, spotted gar, Mexican tetras, and gray redhorse, an elusive silvery fish that tends to hang out on the gravel or sandy bottom. Of these, only the gray redhorse, bass, bluegill, gar, and redear sunfish are native. The rest have been introduced for sport fishing or by people dumping their fish tanks into the river. Unlike tilapia and plecostomus, however, none of these species have proven harmful to the river’s ecosystem, and they’ve been allowed to thrive.
Attempting to photograph these various fish, I’ve learned a good bit about their behavior. Largemouth bass, the top predator in the river, are quite assertive; they will come close, stare at me, retreat, and then repeat. What I’ve found most surprising, and sometimes entertaining, is the aggression of the redear sunfish. Though not as large as the bass, which can grow to more than a foot in length, these sunfish are no less sturdy. Identifiable by their red patch, the “ear” on the side of the head, redear sunfish are easy to find during breeding season, usually in summer. Males congregate in groups in relatively shallow water and create saucer-like nests by fanning silt and gravel with their tails. Once they manage to attract a female, they guard the nest religiously. Several summers ago, I came across one of these communal nesting sites under a bridge in Sewell Park. While attempting to photograph the eggs, I was startled when a large sunfish came up and head butted the hand holding my camera. This charging behavior has occurred any number of times since then, sometimes ending with a bump to my hand or arm, sometimes with only a scowl.
Rio Grande cichlid
While both the redear sunfish and largemouth bass appear to glower at me, Rio Grande cichlids merely look quizzical. Usually a dark blue gray with tiny white spots on their broad foreheads and black bars on their flanks, cichlids bear an expression of perpetual bewilderment, emphasized by their wide mouths and human-like lips. Unlike the sunfish, cichlids seem to deposit their eggs willy nilly—on flat rocks, on sand, wherever they find an open spot. And instead of ramming my hand when I get too close, both the male and female simply swim around and around the nest, in effect saying, “Here are our eggs!”
In fall, all of these fish, with the exception of the smaller sunfish, tetras, and bass, seem harder to spot. I suspect that they’re farther downriver, where they can find slightly deeper water and more cover. Come summer, I’ll see them again.
What I do find more of in the fall and winter, though, are turtles—perhaps because they feel less afraid with fewer swimmers in the river, perhaps because the river is more clear with the crowds gone. In any case, I begin every swim by stopping by the stand of pondweed near Dog Beach, lingering to look for the yellow and green striped Texas river cooters sleeping or grazing on plants. If I’m lucky, and the turtle doesn’t notice me, I can photograph her before she burrows into the vegetation or darts away. If I’m really lucky, I’ll capture the smaller male, too, usually shadowing the much larger female, who tends to ignore his pursuit.
Red-eared slider (left) and common musk turtle (right)
Identifying red-eared sliders is sometimes harder. As these turtles age, not only does that red “ear” become less pronounced, but the carapace, neck, and head can become almost black. A turtle with these characteristics is said to be melanistic. While cooters seem more common on the stretch of the San Marcos River from the dam to City Park, red-eared sliders can also be seen, usually alone, sunning on a partially submerged tree limb or log.
While I also see spiny softshells and common musk turtles, photographing snapping turtles is the most thrilling. For years, I’ve known that a snapper lived under the dock in Sewell Park. Friends at the Meadows Center have speculated that the animal may be as many as 50 years old and weigh 25 pounds. Hearing that, I avoided swimming too close. As I’ve become braver, though, I’ve ventured in, finding the area to be a haven for sunfish, bass, the occasional red-eared slider or cooter, and the elusive snapper, too.
The first time I saw it, roughly a year ago, I was snorkeling through a stand of arrowhead and wild rice, looking for a tilapia that had just darted by. Initially, the snapper appeared in my periphery, a dark shape some distance away. Then, like a bull about to charge, the turtle lowered what passes for "shoulders," dropped its head, and started forward. It took a second or two for all this to register, but when it did, I started backing up. In a hurry.
Common snapping turtle
Later, I discovered that the snapper’s behavior was more the result of curiosity than aggression. In the river, these turtles are docile; only when harassed, particularly out of water, will they bite. I’ve seen the Sewell Park snapper a couple of times since, usually spotting that prehistoric looking tail first. It’s a startling sight, but a look that’s served the species well for 90 million years.
The most recent time I saw the snapper, which I’m guessing is a male based on the size of his tail, I discovered why I’ve missed him for so long. For starters, these turtles are primarily nocturnal, and I typically swim in the mornings. Any overlap in our schedules is accidental. Equally important, they conceal themselves very well. Right before my last encounter with the snapper, after I had already given up seeing him, I was making my way through a mat of floating coontail, heading for the river’s main channel. Glancing to my right, I spotted him grazing on low-growing vegetation. After a short time, he turned, stretched out his extraterrestrial neck, and raised his snout toward the surface to take a quick breath. And then, as if moving in slow motion, he turned back in my direction, began wedging himself into another mass of coontail, and disappeared. I wonder how many times I’ve unknowingly swam over him as he rested amid plants or buried himself in the mud.
Snorkeling in the San Marcos River, whether staring into the face of a largemouth bass or tracking the elusive snapper, I’m always reminded that I am the stranger here. I am the one intruding, the one who must learn a new rhythm, a new way of seeing. If I can do this, with patience and curiosity, I might also learn to better document this underwater world and give those who’ve never seen it a reason to let it abide in peace.