What is temperature?
The water temperature to a river or stream is very important for water quality. It is the measurement, in degrees Fahrenheit or Celsius, of water.

What factors influence the temperature of water?
1. The amount of shade provided by surrounding trees help cool the watershed. When people cut down trees this often causes soil erosion, which can increase the amount of suspended solids in the water. As a result, the turbid water’s particles absorb the sun’s rays, which cause the water temperature to increase.
2. The depth of the watershed allows deeper waters to remain cooler than compared to shallow waters.
3. Cooler water temperatures are expected in the evening and warmer temperatures are expected during the day when the sun is out.
4. The reduction of water flow near operating dams may increase water temperature.
5. The air temperature which change seasonally. Water temperatures can range from 0 degrees Celsius in the winter to 30 degrees Celsius in the summer.
6. Confluence of streams. A natural method of cooling a body of water is the induction of colder water from a tributary.
7. Thermal pollution may cause a watershed’s temperature to increase by adding warm water. Industries such as nuclear power plants may cause thermal pollution by releasing water used to cool machinery. Thermal pollution may also be caused by rain water running off warm urban surfaces, such as streets, sidewalks, and parking lots.

What is the optimal temperature for most aquatic plants and animals?
1. Temperature preference may vary among species, but all species can tolerate slow, seasonal changes better than rapid changes caused from thermal pollution. Thermal stress and shock occurs when temperatures change more than 1-2 degrees Celsius within 24 hours.
2. Most aquatic organisms live in an optimal temperature range of 5-25 degrees Celsius.

What factors are affected by your watershed’s temperature?
1. Increases in water temperature can cause changes in aquatic plants. For example, as the temperature increases, the rate of photosynthesis increases. As photosynthesis increases, the number of aquatic plants increases. This can lead to a number of plants or an algal bloom. The faster plants grow, the faster they die. When they die they are decomposed be aerobic bacteria, which consume oxygen in this process. This event may also decrease the amount of dissolved oxygen in the water, which organisms need to survive.
2. Increases in water temperature can also cause changes in aquatic animals. For instance, as water temperature increases so does the organism’s metabolism. When this occurs, they need more dissolved oxygen and more food supply. If the amount of dissolved oxygen needed is unavailable, they may die. Cold water holds more oxygen than warm water. The more oxygen in the water, the more living things it can support. They may also die at a faster rate because of their increased metabolism and because they can not tolerate extreme heat. Some animals may be able to acclimate to a certain range of water temperature. Other animals may be able to migrate to regions where the water temperature is best for them. This may affect the food chain and may cause the depletion of a food source for other aquatic species.
3. The temperature of water may also influence the sensitivity of aquatic animals ability to resist toxic wastes, parasites, and diseases. Bacteria and other disease-causing organisms grow faster in warm water.
4. Increases in water temperature can affect hatching and development of aquatic animals. Fish larvae and eggs usually have a more narrow temperature requirement than adult fish. Also, the optimal temperature of Brine Shrimp embryos to leave their shell is at 25 degrees Celsius or 77 degrees Fahrenheit.