PLP,
I think a lagoon would be great. They can only be good for general prey species diversity and health. I think every pond would benefit from ~30% shallows, thickly weeded in. A large lagoon may cause some darkening of the water, but I wouldn't think
30% or less would. Mosquitoes are not a problem, as gambusia and shiners feast on the larva. I think lagoons are not popular because they are considered unsightly or unmaneagable. During dry spells, they contribute a lot to evaporation. During real dry spells, they may even dry up entirely in some areas. My pond is over half finished. I wish I had made it 30% larger and included about 1/2 acre of lagoon.
