Our yard haunt has a bridge over a haunted river. We made the river from a water blob (plastic sheeting melted together to form a pillow. Fill with water. Voila) Problem is, my water blob rolled over on itself, broke the fence and rolled down the street! I chased it down and it burst in half, exploding all over me. Now I have a broke fence (I can repair) and no river! I'm out of time and ideas. How do I make a fake river really quickly?