Water temperature is very important on not only the river itself but the aquatic life that makes the river its home. Natural rivers tend to be homogeneous in nature or the same temperature throughout. However a river with a dam is a lot different. Since the water comes to rest before a dam the water temperature tends to be layered. The water is generally warmer towards the top and cooler on the bottom. When water is released downstream it tends to come from the bottom of the dam thus releasing cooler water down the river. Aquatic wildlife such as insects and crustaceans depend on a regular water cycle of temperatures throughout the year. When that changes by releasing cold water down the river, it compromises their survival. An example is an insect may feel the cold temperatures and delay its metamorphosis. This may mean that it will be living in the depth of winter instead of the fall which will result in an overall destruction of the insect.