Can we assume that your steep banks have some slope-pitch or are they vertical? Vertical banks could cause you problems with cave ins, erosion and slippage. How well can vertical banks be compacted to miminize leakage? 2:1 slopes-pitch as steep banks are best for stable non-sloughing compacted sidewalls and 3:1 'pitch' also work well.
Hybrid water lilies:
1. since the pond is new it is best to put a little topsoil (6") in the areas where you want lilies. Lilies can grow easily in 2'-3' of water which is probably a better depths considering water going down during dry periods. IN one area maybe put larger rocks down to 2'-3' and plant the lilies on a ledge there below the rock line. that should be aestetic when they bloom and provide small fish-crayfish extra rocky cover.
2. Hybrid lilies will spread fairly slow so I would plant them about 5 to 30 ft apart depending on the size of the lily (dwarf, small, medium, large).
3. Lilies grow fastest in soft sediments and shallow water. Much slower in hard packed clay bottoms. This can affect the spacing of plantings.
4. Lilies do best with at least 4 hrs of direct sunlight.
See this link for more homework about hardy hybrid water lilies.
If you have never dealt with hybrid water lilies you should read my article in Pond Boss magazine about what to do and not to do and how choose, plant, transplant and to control them.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=110943#Post110943Repeat from the link above:
1. WATER LILIES IN PONDS? Part 1. by Bill Cody March -April 2010: pg 36-38. Types of floating leaf lily-like plants, their features, and control methods.
2. HYBRID WATER LILIES Part 2. Jul-Aug 2010: pg 48-52. All about hybrid hardy water lilies, root types, choosing from the many varieties, numerous examples, planting, dividing and transplanting, sources.
