What are expected Dissolved Oxygen levels?
Target dissolved oxygen levels vary depending on the organism of concern, because different types of aquatic life need different levels to survive. As dissolved oxygen levels in water drop below 5 mg/L, most aquatic life is put under stress. The lower the concentration, the higher the stress. Colder water fish (such as trout) need levels above 6 mg/L, and may require levels above 7 mg/L for spawning. Warm water fish can usually tolerate levels as low as 4 mg/L. If oxygen levels dip down to 1-2 mg/L, even only for a few hours, it can result in large fish kills. Because dissolved oxygen is lowest in the early morning hours, this is the best time to determine whether oxygen is declining to dangerous levels. Stream Team Dissolved Oxygen results Dissolved oxygen concentrations on the Goleta Creeks and Ventura River from April through June 2004 are shown on the figure found in the respective July 2004 Newsletter. The grey bars indicate the mean (average) of all measurements since June 2002;
