5 /5 pog expat: Been here a few times.
Water source directly from spring.
Parking can be a challenge.
Kerbey Lane cafe next door
221 E Sessom Dr, San Marcos, TX 78666
GG map: https://www.google.com/maps/place/?q=place_id:ChIJsUcUaO-pXIYRiZwkTMc66ng