Red-eared Sliders are considered semi-aquatic turtles, but they are inclined to wander. I have often encountered these turtles quite some distance from a suitable body of water. I found this Red-eared Slider attempting to cross the White Rock Creek Bike Trail in Lake Highlands. There was a lot of bicycle traffic on the trail this day, and the turtle was stalled. Every time he was ready to attempt a crossing another bike would zoom by, causing the turtle to retreat back into his shell.
So where did this turtle come from? Well, White Rock Creek is very nearby. But, a more likely spot might be the pond system just a few hundred yards/meters south on the bike trail. Red-eared Sliders and other species of turtles can frequently be seen basking there.