Chlorine is used to kill bacteria in the water at treatment plants. This chlorine can be harmful to some aquatic species. Based on this information, what other step must be taken in the treatment of water?

The chlorine must be removed before the water is released into the ocean

One of the easiest and cost effective way to clean water is to add some amount of chlorine into it. But if chlorine is added in excess then the water becomes unfit for consumption.

So, when chlorinated water from treatment plants is disposed into rivers etc then it becomes harmful for aquatic species as excess of chlorinated water can lead to death of living beings.

Hence, chlorine must be removed from water before releasing the water from water treatment plants into rivers, lakes or oceans.