Dam/dæm/ Definition 1 of 4Pro Tip 1/3Water Management Dams control water levels, often creating reservoirs for water supply or irrigation. The valley was flooded by the dam to create a reservoir. Pro Tip 2/3Power Generation Dams are critical in hydroelectric systems, using water flow to generate electricity. The new dam is part of a hydroelectric power station. Pro Tip 3/3Environmental Impact While useful, dams can disrupt ecosystems and impact wildlife habitats. Environmentalists expressed concerns over the dam's impact on fish migration.