Great place for a short hike
Pedernales River Nature Park is LCRA (Lower Colorado River Authority) park located just outside Johnson City between San Antonio and Marble Falls, The park contains a number of trails in a small area and is a wonderful walk. If you want more extensive hiking and river views Pedernales Falls State Park is nearby and worth the visit anytime of year.
There is a $5.00 usage fee, something that has the locals up in arms, but for me it is better to see this nominal fee charged than the land go to real estate developers.
I thought the place was wonderful. Great example of Texas in late fall.