You may be interested in checking out the Luling Zedler Mill Paddling Trail, it is one of the only inland Paddling Trails in Texas. The San Marcos is a very calm river most of the time, so the only issue you really have is minding your take out because not much passed it is a pretty sizable drop off caused by the dam. Zedler Mill is the takeout spot, if you are looking to walk around it for a bit it is somewhat interesting (more so at dark because it is supposedly haunted), but you need to be very careful if you go up into it because the wood is old. Luling is also the perfect place to end a late afternoon trip because there are a few excellent small local restaurants in town, one being an excellent BBQ place. I have not done the Luling Paddling Trail yet, I have been out to the river and checked out the Zedler Mill, but one of these weekends I am going to get to it.
http://www.tpwd.state.tx.us/fishboat...inland/luling/