A small change in temperature can impair the life cycle of a fish. Heat pollution is caused by power plants and factories. They draw in water to cool their systems and then discharge it back into the stream. Other sources are from dams and from removing shading vegetation. This becomes a problem because it increases the area of stream exposed to sunlight.
Sediment Is the soil, sand, and materials washed from land into waterways.
A healthy stream will have some sediment, but an excess amount of sediment can smother bottom-dwelling aquatic life, clog the gills of fish, and block needed sunlight for underwater plants. Excess sediment can be caused by construction sites where erosion barriers are not maintained. Poor agricultural practice is another source. Not enough vegetation on banks or animals grazing too close to the stream bank can also be possible sources. Oil Free-floating oil can coat aquatic life and destroy it.