After a dam is completed or in full use its harmful effects can be felt by all living things within the ecosystem. Communities that have inhabited the land for generations are often displaced in numbers that can rival large cities within the United States. By displacing these individuals from their known lands, their ability to survive with sufficient food and resources can be problematic. The disruption of the waterway, has in a sense, broken the chain of connectivity that causes environments to thrive and be sustainable for indigenous individuals. These mega dams are "locally disruptive, lasting and often irreversible" (World Commissions).
In addition, the machinery that was used in the building process is often abandoned on site, because it is sometimes too difficult to remove. By having these machines left, either on the embankments or in the flood zone of the reservoir, the ability of plant-life to grow back is diminished and water quality is effected.