POSITIVE EFFECTS:

• Creation and/or enlargement of riparian zone habitats below dam
• Flood control
• Change in eco-system can support a variety of introduced species

NEGATIVE EFFECTS:

• Sediment buildup behind dam
• Decrease in biodiversity of riverine system
• Destruction of natural habitats
• Block migration patterns of anadromous fish and other aquatic species
• Loss of nutrients in the water
• Release of cold, clear water
• Decrease in aquatic primary producers
• Release of anoxic water
• Increased competition between endemic and exotic species
• Increased erosion
• Increased variations in flow rates and temperature of the water
• Division of populations which leads to decreased gene flow and genetic variation
• Decrease in biodiversity of the riverine system
• Inundation of other riparian zones upstream from dam: harms amphibians/terrestrial species
• Decline in native fish populations
• Biotoxicity of built up sediments
• Loss of water through evaporation off reservoir
• Oil released from anthropogenic sources
• Loss of organic debris below dam
• Loss of seasonal floods which cleanse eco-system, maintaining dynamic balance
• Release of PCB's from circuit breakers in hydroelectric dams harms Bald Eagles