Meanwhile;
Texas has a long history of promoting private land ownership and protecting land owner rights.
Think back to the huge ranches, etc.
The state purposely avoids purchasing large tracts of land that potential impede private development.
Texas (by proportion) has one of the smallest percentages of state or municipally owned land in the nation.

Likewise, when utility or other private entities build lakes, the tendency of the state is to be as non-restrictive as possible.
Most of the lakes in Texas are not truly "public" lakes. They are lakes that private entities have granted public access to.

Water rights in Texas are HUGE dollars.
Contracts around lake usage, access, and the rights to the water within are way beyond the scope of discussion here.
I think (??help here if somebody knows) that TPWD and "the state" have "negotiated" access to many of these otherwise private lakes.
In this negotiation, one would think there would be constraints on how the lakes were managed in consideration of various public interests.
i.e. you cant eradicate weeds without mutual agreement by TPWD biologists; or something like this.
It's obvious that if TPWD is negotiating the access agreements, they ain't doing it in the way we would like them to!

Protecting lakes from large scale weed eradication would require legal work and possibly legislative action.
This stuff cost dollars.
Without an organization that can raise dollars and sponsor these efforts, well . . . you're right where we are now.

Senko;
You work for TPWD dont you!!??
Come on now!!
It's pretty obvious.
Dont be hurt. We all like you.