Because there is a trail righ near the water line and one above it the milage stated here is about right. The main trail is an out and back you don't elect to try the lower trail when turning back at the dam.
Texas Parks and Wildlife was running some program for women outdoors this weekend, so the park was fairly packed with campers and day visitors. Even so, there were not that many people on the trail itself.
I have to admit it's not really that great of trail, though it is well maintained. It provides a nice little stroll for park visitors who are there, but I wouldn't recommend travelling very far for it.