I had a few reasons for adding ponds. I currently have one by the house, one down the hill beside one of the growing areas, and am in the process of creating third by another growing spot. I also have a large catchment tank that serves the function of a pond beside the barn and services the main veggie gardens. Plus one small 300 gallon mini pond that provides water for the sheep.
Reason one, mosquito control. All the ponds have mosquito eating fish in them. That's a major benefit for us. Reason two, water storage for the gardens. Surplus rain water can be saved for dry spells. Reason three, fire use. Both the house and the barn have large ponds that could be used for firefighting. Reason four, food fish production. The two largest ponds host edible fish. Reason five, livestock water. The mini pond services the main corral where the livestock come each morning to drink and get their grain.
Side benefits include harvesting the pond plant life for feeding to the
chickens. The
dragon flies use the ponds for reproduction. The Muscovy ducks have one favorite pond that they like to visit daily for a bath. I'm not thrilled about that, but I let them live their lives without much restraint. And finally, I just simply like having them. We built a raised deck beside one of the ponds where we can eat a meal or simply sit and relax. The pleasure factor improves our life.