Add River

To shape the bottom of our valley we will now create a River Layer. When you first add it to your terrain World Creator will automatically generate a river network based on your terrain. As we don't need that simply press Clear Rivers on the left side while in Edit mode. After that we use Shift + LMB to place a new spring and then Ctrl + Shift + LMB + Drag to drag out the rest of our river stream from that spring.

final river