Cold water can hold more of any gas, in this case, oxygen, than warmer water. Warmer water becomes "saturated" more easily with oxygen. As water becomes warmer it can hold less and less DO. So, during the summer months in the warmer top the portion of a lake, the total amount of oxygen present may be limited by temperature. If the water becomes too warm, even if 100% saturated, O2 levels may be suboptimal for many species needed high DO (e.g.trout). What environmental factors can upsetsaturated dissolved oxygen?