Aquatic animals, just like humans, need a moderate temperature range to live in, not extremely hot or cold temperatures. As the temperature of streams falls outside a range of normal temperatures, aquatic organisms are stressed and become less abundant. Water temperature is affected by riparian cover and human impacts.
Water temperature has an important effect on water chemistry. For example, cooler water can hold more oxygen and cool water temperatures are required by many pollution sensitive species, such as the rainbow trout and mayflies. To read more on the importance of water temperature, go to this government Web resource: A Citizen's Guide to Understanding and Monitoring Lakes and Streams.