Waste water treatment plants
Usually a wetland is not having much free oxygen and not much flow. When wastewater treatment plant effluent are discard, they usually are in a river where water is flowing to allow for dilution because there is still a bit of nutrients and bacteria that are cause less harm when you have a lot of flow. I would be surprise if the water would be sent directly to well water. If it is the case contact the local agency of your area.