Yeah, there are subdivisions all along the Trinity River below Lake Livingston and above Liberty.
The geometry's not real good for Anahuac either, but the pros will know if a flood would disperse across the marshes before it got there.
There are houses there? I dont see that many on the Google Earth....how far out of the banks will that river flow?
A few years ago Canyon Lake (west of New Braunfels) flooded and the spillway was "used" for the first time. I don't think they realized what the results would be. Over 800 homes were damaged or destroyed and the water carved a gorge.
Here's a link that talks about the Canyon Lake Dam and there's a picture near the bottom of the gorge.
http://www.edwardsaquifer.net/canyon.html