When a stream is channelized, the sun heats up the concrete which heats up the water.

Many dams release water from the bottom of the dam which is much colder than the rest of the river. This makes the river below a dam to cold for some fish to survive.

Animals grazing near a stream can eat all the plants that protect the stream. When this happens, there is no shade and the sun heats up the water in the stream.

Cutting down all the trees near a stream takes away the shade. without shade, the sun will heat up the water in a stream.