In addition to growing beautiful plants and soothing fish, a water garden can help the neighborhood birds. It provides a place to bathe. In the heat, they can get a drink. Be sure to use only natural products in your pond that don't harm animals.
There isn't a problem with it, since the water is not stagnant. We have a pump that pushes water up a little slope, then it runs down a small stream. The water is constantly circulating. Also, we have fish, and maybe they use the larvae for food. Although, I really have never seen larvae in the pond.