Subject: How does running water freeze?

I know that as water is running it cannot freeze (movement requires energy and 
the temperature of the water needs to be higher than freezing inorder to move) 
How is it that at night when outdoors it is below freezing some water rushing 
into the drainpipes doesn't freeze while others (not too far from the same 
location) do freeze? also on that night in particular when I noticed this 
there was water that obviously ran down a hill and froze on the way down, if 
water is rushing at therefore won't freeze how did that water freeze?

Re: How does running water freeze?