Hi Allen,
I would suggest you build a berm tall, wide and long enough to keep the water away from your septic field. You can plant trees, shrubs and plants on the berm. It's basically a dirt levy, but it can deteriorate over time.
You may want to contact whoever owns the swamp and your local authorities as another person's water shouldn't be allowed to invade your property.
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.