A start would be some Arrowhead, pickerel weed, maybe soft stem bulrush, sedges, etc, but these are all border/bog plants and will establish in 10" or less. Sago pondweed tubers added in early spring in cheese cloth will help. Broad leaf or american pond weed would be beneficial as well but hard to find. Some lilies wouldn't hurt as long as they are not lotus of some sort that goes crazy.
