Dewayne,
Don't dig the trenches. Disturbed dirt moves with water. It will end up in your pond. Terraces are good if you want to redirect water into your pond or if you want to increase watershed size to feed "new" water to the pond. Sounds like terracing might help you.
The green film on top of the water with air bubbles is probably algae. It's normal. But, if you don't like it, you can get rid of it with an algaecide, microbes, barley straw or wait until the daytime temperature gets hot for several days and algae will go away.

Teach a man to grow fish...
He can teach to catch fish...