If you have a pond that can vary in depth as much as mine, there is no right height for a fixed dock.
I ended up going with a floating dock. It's always the same height from the water, or ice, stays in year round.
The floatation I used is plastic 55 gallon drums. Just calculate how many you need to keep them more than 1/2 way above water line, this way the caps are never in the water and cannot leak.
