Water Gardening: Need advice., 1 by snowhermit

snowhermit wrote:
This is a pond that my SIL made for my daughter last fall. She is going to be putting some trout in it next week. She might also use it to swim in this summer. It is fed by an underground spring.
Since neither of us have any experience with ponds I'd love some suggestions on what type of water plants would be good to give some protection to the fish from the sun and predators and also be safe to swim in. She is in zone 4.
Her birthday is coming up and I would like to buy her some starter plants but I have no idea what to get.
Any help will be appreciated.