A 6' avg-depth is relatively substantial, so I'll assume that you must have some fairly deep water in the pond's interior - 15'+?
Depending on the pond's design, always consider that the shallow littoral zone has a significant effect on the overall avg depth.
Review this simplified depth-illustration and the associated calculations, and let me know if you still think your pond has a 6' avg depth.
Any idea of your pond's pH-range (early AM thru late afternoon)?
Also, are there any desirable plant species that you want to specifically preserve?
Good to hear about your local rep. I don't know him personally as he's probably in the Ag-side of the company, but great to know that he's on top of his game.
