Dissolved oxygen levels below 3 ppm are stressful to most aquatic organisms. Levels below 2 ppm will not support fish at all. Low dissolved oxygen levels can be the result of elevated temperature and thus the inability of the water to hold the available oxygen.Low dissolved oxygen levels can also indicate an excessive demand on the oxygen in the system.Some pollutants such as acid mine drainage produce direct chemical demands on oxygen in the water for certain oxidation-reduction reactions.ow dissolved oxygen levels can also indicate an excessive demand on the oxygen in the system. Some pollutants such as acid mine drainage produce direct chemical demands on oxygen in the water for certain oxidation-reduction reactions.