Many areas will have restrictions about what can be planted (or even removed) along any bodies of fresh water. I'd check with your local municipality before proceeding further.

I like the idea of the bark mulch. Perhaps you can gather some flagstone on the property to make a path to the water. Clean it up, add some groundcover native to your area and you will get other ideas as you work at it.

What zone Are you in? I know hostas are common in a lot of landscapes so people get sick of seeing them. I use them everywhere! They do great in the shade and people in my area give them away for free! When planted with ferns and ground over they can make a really stunning shade garden

. Ferns love the shade too and could add great movement with a nice lake breeze.