Water temperature can prevent plant respiration and photosynthesis in marine organisms however it fosters increases in algal photosynthesis - therefore algae like the toxic blue-green algae increase during the warm summer season or when water temperatures are warmer than usual. Scientists predict that climate change will have many effects on freshwater and marine environments. These effects, along with nutrient pollution, might cause harmful algal blooms to occur more often, to be more intense, and inhabit more waterways.

Thermal pollution: is the introduction of water that is warmer than the body of water into which it flows for example power plants discharging hot water that has been used to cool equipment directly into streams. Urban runoff is another source of thermal pollution as water that has been heated as it flowed over parking lots, streets and sidewalks enters nearby waterways. Removal of riparian vegetation can contribute to thermal pollution by decreasing shade, thereby increasing solar heating of the water's surface. It also contributes to increased erosion and sediments in the water. These particles absorb heat from sunlight rather than reflect it heating the water further

Correlation between increased temperature and lower dissolved oxygen levels: Warm water is less capable of holding dissolved oxygen. Low dissolved oxygen levels is magnified because metabolic rates of aquatic plants increase as water temperature rises, thus increasing their biochemical oxygen demand. Low dissolved oxygen levels leave aquatic organisms in a weakened physical state and more susceptible to disease, parasites, and other pollutants.

Temperature should be measured at the same place within the stream at which dissolved oxygen is measured allowing the correlation between the two parameters to be observed.

Compound Toxicity and Increased Water Temperature:There is also a correlation between increased water temperatures and solubility (therefore toxicity)of certain compounds. These elements include heavy metals such as cadmium, zinc and lead as well as compounds like ammonia. Water temperature can not only increase the solubility of toxic compounds, but it can also influence an organism’s tolerance limit.

Conductivity and Salinity in increased water temperatures: Warmer temperatures increase waters viscosity and reduce conductivity. Warm water can also dissolve several minerals and salts more easily than cold water, and therefore the ionic concentration of salt is often higher than it would be in warmer waters.