This is a stream right next to the marker, taking a closer look you can see the springs bubbling up. There were at least 3 right in this area.
I found this interesting bit of history yesterday morning when I was out walking with a friend. The marker is at Landa Park in New Braunfels. A mission was started there, but unfortunately didn't last but a few years. Part of the reason it was chosen was for the springs that come up from under the ground and the near by Guadalupe river. Another reason was that the Indians in the area would not go to the Alamo mission.