Teresa
What size pond are you looking at? With koi you will need enough room for them to swim and good filtration. Filtration is key to keeping the water clear and healthy. You will want to be able to turn over the entire volume of your pond in an hour's time.
Instead of shelves, we put bogs around the edges of the pond. These bogs are what would normally be the shelves in the pond, but instead of an open shelf, DH foamed rocks on end at the end of the shelf. After this area was dry, then prewashed pea gravel was used to fill these areas. Plants were then planted directly into these areas. We have a small pump that empties directly into the larger of the bogs and the water is then pushed through with the pea gravel and the roots from the plants filtering the water into the pond. Koi produce quite a bit of waste, so it is important to stay on top of the filtration in the pond.
I tried to find photos that show what I am talking about with the bogs. Typically we open up our pond around the beginning of March and the water celery is already starting to grow - one thing I should mention, we put in the water celery not realizing how invasive it can be. It is great for the filtration,but it has started to jump into the other bogs.
Bonnie - so good to see you here - I am wondering if you can find some of the photos from when you did your last pond? That may help Teresa.