The Austin Parks Foundation website confirms that this is an official off-leash dog park (other than the playground areas, where leashes are required). The walk to the first creek crossing is 3/4 mile down what is basically a Jeep trail. From there you can play fetch in the shallow creek, then cross the creek and ascend a small hill to the rest of the trails. There is a veritable spaghetti bowl of trails up there, so you can really choose your own distance. I've done a couple of them, and even with a map, it is easy to get turned around since they're so twisty. Horses are allowed on these trails, so there is a good amount of horse poop (dogs think that is super fun to roll in!) but I've never actually seen a horse in the 5+ times I've been there this year.