Lilies wont thrive in flowing water, so it may be why you had trouble near the stream.

You are going to have to protect the plants with cages, and they must be large enough to keep geese necks from getting at them. Also will need to protect lilies from turtles.

Eel grass should love your conditions, so protection is important. Also water clarity is important so you can plant deeper to keep out of reach of the geese.

Lastly lift the diffuser off of the bottom, you dont want to circulate bottom material, just O2. This will help clear water.