Hi Rig Magician, and welcome to Texas! Although I've never been there, Twin Lakes seems to be the most popular spot to dive in that area, I think it's in south Houston. It's been improved for divers, sunken items and platforms, etc. Some of the Swampdivers have actually volunteered a lot of the labor for the improvements. It has fish and vegetation, supposed to be a nice place to dive. I've seen reports of 2-30 ft vis, depending on the season, etc.
The other place I've read about in that area is Blue Lagoon, which is supposed to have great vis, but has no life. It's used a lot for training in the Huntsville area, and it's north of Houston. Anywhere you go in Houston, you're going to be driving anyway- it's immense!! Have fun, give a report!
Foo