• EAHCP Steward

Out with the Old, In with the New

“In 2013, when we first started to take on the removal of the non-native plants in Landa Lake and adjacent reaches of the Comal River, I thought we wouldn’t be able to get it all done,” said BIO-WEST Ecologist Casey Williams. “The invasive Hygrophila was the most pervasive plant there. It was very dense and looked like huge swaths of muck in the river. In some places, it controlled the river from bank to bank. Eventually, we were able to cleanse the lake and river of that huge mess, but it sure seemed like an insurmountable task in the beginning.”

Williams explained that the big picture goal of this program was to decrease the dominance of non-native vegetation in Landa Lake and the Comal River and restore those environments with native plants that would be more conducive to the health of endangered species living there. In the two decades before the EAHCP began its implementation, the Comal River and a part of Landa Lake were overcome with non-natives, especially the hygrophila.



“Hygrophila originates from India, Burma and Malaysia. There is documentation that shows it was transported to Ohio as part of the aquarium trade around World War II,” Williams noted. “From there, it was shipped to different locations including here in South Texas. When people started to dump their aquariums in the river, we found out how invasive this stuff really is. Hygrophila is kind of a rare invasive in that it only really did well in Texas and Florida, but it can quickly overcome an ecosystem, and so it needed to be removed.”


At the start of the project in 2013, Williams’ team mapped the Comal system to get a baseline of where the non-native vegetation was in anticipation of doing comparative mapping in subsequent years. To create the map, Williams would head out in a kayak equipped with a GPS system, paddle around a patch of plants and then add the GPS coordinates to a map. Additional information would be added to the map to describe the mix of plants there and the total area of the patch. Knowing the size of each patch also helped program managers know how much more natural habitat could be restored, which in turn helps endangered fountain darter populations grow.


“In 2018, we will be creating another map similar to the original base map we did in 2013,” Williams said. “Once we finish this year, we’ll have an excellent means of demonstrating the progress we’ve made in changing out the non-natives for native plants. I’d say that at this point, we’ve removed almost all of the hygrophila in the target area. We’ve also planted 50,000 native plants to get us a lot closer to restoring the ecosystem. We do use drones in the mapping process. And some of the aerial photos show very clearly how the native plants are thriving again in the Comal system.”