Invasive plant species spreads in central Texas lake


SALADO, Texas – An invasive plant species that is spreading in Stillhouse Hollow Lake has recently raised questions.

What would you like to know

  • Hydrilla, an aggressive and invasive plant species, was first detected in Stillhouse Hollow Lake in Bell County in 1995
  • Since then, the plant has proliferated a lot in the lake
  • Biology professor Dr Laura Weiser Erlandson says the plant can have adverse effects on wildlife and affect fishing
  • The entire lake is currently unaffected by the invasive plant, and Texas Parks and Wildlife currently has no plans to address the lake.

Experts say the hydrilla was first discovered in central Texas Lake in the 1990s, but it is now more abundant than ever.

A Central Texan struggles to explain what this means to fishermen, kayakers and swimmers. Bob Maindelle is a full time professional fishing guide. He is the owner of Holding the Line Guide Service.

“It’s just a great feeling to be able to serve people by doing something that you really love to do,” Maindelle said.

Lately, a number of people have asked him: what grows in Stillhouse Hollow Lake?

“My clients started asking questions,” Maindelle explained. “‘What’s that thing in the lake? Is it the bottom? Is it algae? Is it filth?'”

It is an invasive plant species called hydrilla. Experts say the hydrilla was first discovered in central Texas Lake in 1995.

“Maindelle, here in 2021, it is at the maximum that it has spread and at its greatest height during these 20 years”, explained Maindelle.

While there are benefits to growing hydrilla, such as improving the population of largemouth bass, hydrilla has the potential to become a problem. At this point, the hydrilla made some coves inaccessible to fishermen.

“A creek in the upper third of the reservoir closest to the river is where hydrilla growth is most abundant,” Maindelle said. “It is now difficult for a bass fisherman to have a trolling motor or an outboard motor here. A bank fisherman certainly couldn’t fish from the bank here anymore.

Maindelle says that while this is a problem, the whole lake is not fighting the problem.

“If it becomes so in the years to come, then certainly action may be needed,” Maindelle explained.

Associate Professor of Biology, Dr. Laura Weiser Erlandson, explains that hydrilla grows and turns into a mat on the surface of the water.

“It’s hard for animals to swim through the mats. It’s hard for fishermen to fish through these mats, for boats to walk through these hydrilla-growing mats,” said Weiser Erlandson.

But visitors can help.

“Clean your equipment,” Erlandson said. “Because even a small part of it can be transferred to another body of water. “

Texas Parks and Wildlife expects cold water temperatures to reduce hydrilla cover this winter and has no plans to treat hydrilla at Stillhouse Hollow Lake at this time.

However, officials say if the plant begins to restrict access to beaches or boat ramps, they could reconsider their decision.

Full statement from John Tibbs, Texas Inland Fisheries Parks and Wildlife District Supervisor for Waco:

“As you pointed out, it was first discovered at Stillhouse Hollow in 1995, and since then it has fluctuated from very small amounts to covers similar to what is present today. Stable water over the past two years has provided good growing conditions, allowing it to expand, especially in the middle and upper parts of the reservoir. Large areas of the lower reservoir and deeper areas in the reservoirs medium and upper, however, remain hydrilla free, allowing for boating and angling for open water species like white bass.

“Our survey of vegetation at the end of the summer indicated that the hydrilla did not interfere with access to any boat launching ramp. I should also note here that hydrilla beds are very popular with black bass anglers and Stillhouse is no exception. Our electrofishing survey this fall also showed an improvement in the largemouth bass population with higher catch rates of larger individuals as well as excellent spawning. In addition, forage in the form of bluegill, red shad, gizzard shad and thread-fin shad is high compared to historical levels. The hydrilla is an exotic species that can be invasive and problematic in many cases, but in this reservoir it appears to provide good habitat for fish, with a lot of support from anglers to keep it.

The Texas Parks and Wildlife Department is monitoring hydrilla at Stillhouse Hollow. Cold water temperatures will significantly reduce its coverage during the winter, so there are no plans to treat areas of hydrilla at this time. If access to boat launches or swimming beaches become impeded in the future, treating these areas is an option that could be considered. “


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