The shock of these rapid temperature changes can be too much for aquatic life to handle. Humans can alter the land use around a waterway and affect the water temperature. Removing the streamside forests for farming or during timbering eliminates the shade provided to the stream. Sunlight is no longer blocked. The removal of streamside forests and any other actions that promote soil erosion also increase the water temperature as more heat soaking sediment enters the stream.
Urbanization is another heat causing pollution source.
Rainwater that flows over hot paved surfaces warms up and eventually enters the stream. The upper temperature limit, or short term maximum, is set at 30.6 C for the area from the southern shore of Long Island, New York to Cape Hatteras, North Carolina. The weekly maximum is set at 27.8 C for this same area. No regulations are established for the zone containing Western Pennsylvania. A summary of these data is below to provide an understanding of past values of temperature and demonstrate trends or relationships of past temperatures.