Water diversions cause major environmental disruptions. Altering a natural habitat, even slightly, can cause a cascade of events that harm the entire ecosystem. Migratory fish and birds are especially vulnerable to habitat loss. They require two seasonal habitats, in addition to those along their migration routes.
Habitat Loss
Water diversions change nutrient flow, water flow and water chemistry. These changes alter the riparian habitat of rivers and streams. For example, during the dry season, the Colorado River contains little to no water by the time it reaches the Pacific. Many wetland ecosystems have been completely lost to human development. This makes it extremely difficult for migratory birds to find areas to rest and eat as they migrate. Dams can deny migrating salmon access to their native streams to reproduce.
Habitat Fragmentation
Habitat for aquatic species is fragmented by dams, water diversion for drinking water and agricultural irrigation. Dredging of rivers is another way habitat becomes fragmented. Fragmented areas are often too small and disconnected to support mammals that need large territories in order to mate and find food.
Loss of Biodiversity
Aquatic biodiversity has value to humans because it supports and maintains overall environmental health. Humans depend on aquatic environments for resources such as materials, medicines, and food. Aquatic organisms depend on biodiversity for materials, food and breeding grounds. When biodiversity is lost, many living things are affected.