We just were there this past Thursday night on our way back from Colorado. There are 2 distinct sections of the park. The high, scrub desert with Argarita, Mesquite, All thorns, prickly pear, and an occasional live oak, will be hot for hiking. The other part has 100 year old pecans, red oaks, live oaks, with tall bushes. Yes the dogs can swim but they still want them on a leash. I've seen people tube with their dogs. There are 3 areas to swim/get in and out. The most popular is the river crossing. The water tends to be the swiftest there. The second is the "day use area" which you get to by going to the HQ, then exit their driveway, straight across the park road, an down a shady, windy 1/2 mile drive. There is shallow slow water, and deeper swifter water. On the other side of the rapids, the water is colder because there are springs underground in that part of the river. This park is a slower pace from Garner. You should really visit both while your out this way. Everyone has their favorite.
SLRSP slideshow