I was wondering if anyone remembers this 80's, possibly early 90's cartoon where all of the animals in the forest lose their color and turn gray. They also have the help of a doctor who at some point is making root beer from roots in his lab. I remember that they get their color back by jumping into either a rainbow river, waterfall, or lake.
All that I can think of at the moment is an episode from The Adventures of Teddy Ruxpin where the little fobs in the forest start to lose their colors. And they discover that rainbow falls has no water in it. I remember a big pink creature going up and moving the boulder away to make the water come out again. Check out the episode here. https://www.youtube.com/watch?v=YGZMw6uD-fQ