Hydro electric dams destroy existing ecosystems  Large dams wreak havoc with the environment: they destroy habitats and ecosystems both further upstream and downstream. They prevent salmon from swimming upstream to spawn. The water going through them is often warmer and devoid of nutrients, depriving downstream riverine wildlife of their natural habitat. A shocking example is China’s Three Gorges Dam, which Scientific American called ‘an environmental disaster’. [1]  [1] Scientific American, ‘China’s Three Gorges Dam: An environmental disaster?’ 2008