The invasive plant hydrilla is finally under control in Lake Austin, according to a Texas Parks and Wildlife Department vegetation survey.
The survey found no evidence of the aggressive, exotic plant, which has been present in the lake since 1999.
Hydrilla posed significant safety concerns to Lake Austin, as its dense growth impacted flood flows, water intakes and recreation on the lake. It reached a historic high coverage of more than 600 acres in February 2013, due primarily to drought-induced low flows and warmer water temperatures.
The department said the successful control of hydrilla was a result of stocking the lake with sterile Asian grass carp, a fish that targets hydrilla as its main food source.
The department added that while the plant is currently under control, it is probably not eradicated. Over time, the carp population will naturally decline, and hydrilla may re-sprout from its underground tubers. Changes in water flow and temperature may also impact growth rates.
With the decline of hydrilla coverage, a less aggressive exotic plant known as Eurasian watermilfoil has expanded. Though also invasive, watermilfoil can be beneficial, providing habitats for fish and other wildlife while also helping maintain good water quality.
The survey documented that 203 acres of aquatic vegetation habitat, mostly Eurasian watermilfoil, is still present in the reservoir. In the June 2013 survey, there were 330 acres of hydrilla and 135 acres of milfoil.