Another angle to look at is to figure out
why he is doing this. Could it be that he is not getting the required nutrients from his food and is still hungry?
You should check with your vet to see if the food you are giving him is the best diet with the right amount of nutrients needed for his growing stage, as well as suitable portions. He's a growing pup and just may need to have a larger portion to fill him up as he is growing, or a diet that contains more good stuff!
And Stacey B has the right idea: stoop and scoop as it hits the snow!!