Over the past years the hydrilla coverage had reached approximately 300 acres in
2007 choking coves and shoreline along most of the lake.
Texas Parks and Wildlife
recommended an integrated approach to treating the hydrilla that included herbicide
and the addition of
triploid grass carp
that would equal 10 carp per acre of hydrilla.
In April 2007 the city added 2,500 triploid carp and that was followed by an extensive
herbicide treatment in June. Then the July 2007 floods resulted in muddy water which
lasted for several months and blocked sunlight from reaching the plants.
The combination of all these factors (carp, chemicals and muddy water) has resulted
in the reduction of hydrilla to only trace amounts per the August 2008 survey by
TP&W. Due to such small amounts TP&W will not recommend further chemical treatment
at this time.
- are sterile and cannot reproduce.
- feed only on plants, not on fish eggs or young fishes.
- feed from the top of the plant downward; however, where all submersed vegetation
has been eliminated, the water can become turbid as hungry fish eat the organic
material out of the sediments.
- go dormant during the winter and resume intensive feeding when water temperatures
- live for at least 10 years and probably longer in Texas waters.
- grow rapidly and may exceed 60 pounds.
- are difficult to catch with conventional fishing methods.
- most are now gone.