Looks like these roads were submerged when the dam was built and the reservoir filled. The original road can be seen to the SW.
This is the Stillhouse Hollow Reservoir/Lake. It was impounded by the US Army Corps of Engineers in 1968.
See: http://www.tpwd.state.tx.us/fishboat/fish/recreational/lakes/stillhouse_hollow/
It would be interesting to find pre-1968 maps of this area to determine what roads these were...