North shore small wave surfing

Today we went to Waimea beach and got to watch something cool. The beach sits at the base of a valley which has a small stream running through it. Due to wave action, sand gets pushed up into a large hill in front of the stream each winter. This creates a natural dam that the stream water collects behind for months which is about 20 feet above the level of the ocean. Every year some one digs a trench through the sand, releasing millions of gallons of fresh water into the ocean. This produces a standing wave which is perfect for body boarding and surfing. When we first walked up these kids had just a trickle of water moving through a trench about a foot wide. They had obviously been digging all morning. Within 20 minutes it had turned into a roaring torrent. It was amazing to watch how fast it grew and ate away the banks. It all lasted about an hour before the water slowed down but it was fun watching the surf action.