Their metabolic rates are controlled by water temperature. This metabolic activity is most efficient within a limited range of temperatures. If temperatures are too high or low, productivity can decrease or metabolic function cease. The organism can die. These extremes, or lethal limits, vary for different species.
Warm water releases from power plants, industrial facilities.
Slowed water due to small hydropower projects, and diversion dams for irrigation. 12 Hr-TLm is the temperature limit that half of a given species will perish at within 12 hours. This is a very important consideration of stream health. Record the measurement in the temperature data record. Compare your temperature to federal and state standards in addition to the temperature ranges for aquatic life.