FR,
Knowing you are in tall grass prairie country, you may be surprised at just how much organic matter and nutrients are in the topsoil. Sounds like you may have a hard pan underlying. To me its all good. However be careful of have much topsoil remains in the pond. Organic percent greater than 3% is borderline hyper-eutrophic and any shallow areas inundated that have that level or greater organic matter content will grow vegetation prolifically.
I was thinking on exactly those same lines - but wondering if a few hyper-eutrophic areas that prolifically grow vegetation would actually be a benefit to the pond?
I could have a few flat "mesas" in the pond that would be 3-4' below normal pool level. I could cut almost a vertical slope around most of the mesa and go straight to 8' deep water. (I think DD1 was thinking along the same lines.) I would deliberately finish the top of the mesa with good, organic-rich topsoil.
Would plant growth there help "steal" much of the nutrients from my pond water and mitigate the growth of filamentous algae? It would also provide a micro-environment for the organisms at the base of the food chain plus some shelter for the forage fish species.
The groundwater pond that will be my water source is going to be closely tied to the creeks in the area that exist in the same sand layer as the groundwater aquifer. These creeks certainly good a large dose of run-off from adjacent agricultural land. I suspect my water supply will have some residual fertilizer in it during certain times of the year. I may need some area of abundant aquatic plants to help soak up that input.
I think a properly designed pond could prevent any such prolific plant areas from spreading too much by going straight to deep water? Or is my likelihood of getting an undesirable plant that spreads through seeds or floating fragments so high that my entire shoreline from 0-3' will quickly grow enough plants that my pond will not lack for the plant portion of a healthy pond ecology?
(I read almost all of the threads on Pond Boss about vegetation and algae in ponds. This is one of the most common problems from new members. I am trying to solve some of these potential problems during the "design phase", so I apologize for giving everyone such vague data to work with! However, I am pretty confident that if I could give everyone perfect data, this crew could easily create an optimal design.
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