They were my first freshwater dives in years. No, decades. Those long-past dives were in a different part of America. To draw a line under it, I am in a new ecosystem. New critters, new plants, new things to learn about. It’s exciting.
First, a bit about the dive sites. Lake Travis is a reservoir behind the Mansfield Dam, completed in 1942. The dam is across the Colorado River, and the resulting lake floods 65 miles/106 km of river valley. It is touted as some of the best diving in central Texas. Certainly, topside it is a beautiful corner of the world.
The first site is named Cedar Creek Cliff. I do a giant stride at 09:16 into surprisingly warm water. I check my computer and it reads 84*F/29*C. Funny, I notice that there is no salty taste when I put my reg in my mouth. A quick buoyancy check, and we drop down.
Green. Completely enveloped in green. Visibility is at best 2m/6ft and the wall is at least three times that distance away. We follow our compass heading through the murk, find the wall and start making our way. I hadn’t yet unpacked my torch or video light from the move, so everything is still some shade of green. As my eyes adjust and we get deeper the visibility improves, it’s now about 3m/10ft. It is an almost alien view, mostly devoid of life with everything covered with algae and silt. An errant fin will create a cloud, so I’m trying to be extra careful.
Old habits die hard, so I’m peeking into nooks and crannies-looking for shy critters but there is nothing. Maybe I’ll see more in future visits when I have light and when I know more about what I’m actually looking at. At 35ft/10.5m we cross the thermocline.
The temp drops to 64*F/17.5*C. It is startling. The demarcation is so sharp that you can see it. The warm water has a shimmer like you see on the horizon on a hot summer day. A few times I have a bit of fun having my head on one side of the thermocline, body on the other (but then I’m easily amused). The colder water has it’s benefits-the visibility is now about 4m/13ft, and that is the best it will get on this dive.
What I found fascinating is that there are all these tree stumps, leftovers from when the dam was built. Because of the cold water, rot is slow. They have been sitting sentinel 76 years, and if you brush away the silt you can still see the bark. I’m told that in other areas the scaffolding used during the dam’s construction is still there. There were also many farms/homesteads in the valley that were flooded, but I don’t know if any buildings or other artefacts are there. Something to research and maybe see on another day!
Now back at the starting point, the safety stop feels like a spa in the warm water. 44 minutes well spent.
The second dive was at Starnes Island. As we approach from the north-east, we see several police and Texas Parks and Wildlife Department boats controlling access and boat traffic on the north side of the island. They have divers in the water still searching for the body of a man lost just over a month ago (to my knowledge they still have not found him). I’m thinking how crazy it would be if the current dragged the body around the island and one of us stumbled across it! We go round to the south-west side and jump in. It’s 10:57.
Again-very warm water, but this time much better visibility. About 4m/13ft in the shallows. At 60ft/18.5m we can now see almost 6m/19.5ft, so I’m pretty happy. My guess is because the sun is higher, but maybe because the island is out in the middle of the lake, not along a cliff shoreline. It’s mostly the same lunar-type landscape, maybe a few more fish. Once again, the thermocline greets us at about the same depth. At one point during the dive I am surprised to see a diver off our boat swimming below us-in only his t-shirt and shorts. I’m feeling the chill in my 7mm semidry, and this guy is in shorts! I saw him when we jumped in, but assumed that he would stay shallow in the warmth. Then I remember that he told me he is Canadian. Fair enough. Crazy, but fair enough. 50 minutes from giant stride to safety stop.
The sad find during both dives is that sometime in the past year Lake Travis became infested with Zebra Mussels (Dreissena polymorpha). You can see them everywhere you look. They are about the size of a fingernail, reproduce at astonishing rates, have no natural predators, and are altering entire ecosystems. Zebra Mussels are filter feeders of algae, and consume so much that they out-compete native species. Whilst digesting they excrete a chemical that accelerates decomposition. This is a huge problem in the Great Lakes where they are destroying historic shipwrecks. Their procreative talents clog intake pipes and foul boats. Shells are razor-sharp so divers have taken to wearing gardening gloves. They are so destructive that TPWD officers will issue a spot fine if a boater does not completely rinse off the boat, trailer, livewells, bilge, engine as soon as the boat leaves the water. Divers are meant to thoroughly rinse all gear (including the BCD bladder), making sure to remove any plant matter and allow to completely dry for several days before using the kit in a different waterway.
Zebra Mussels are native to the Caspian Sea and first entered North American waters in the 1980s. Most likely they were in freighter ballast tanks dumped in Canadian ports and through the St. Lawrence Seaway. They have steadily worked their way into North American waterways throughout the continent, wreaking havoc.
Here are a couple of interesting articles:
All in, I really enjoyed the dives, the operator and the other divers. But to be honest, it’s pretty rare to come across grub divers. They are out there, but most other divers you meet seem to be good people.