Oxygen Sag in a River

by Shaara Argo

Submitted : Spring 2009

The dissolved oxygen concentration level in a body of water is important in the survival of aquatic life. If this level reaches below 4 mg/L, it can be deadly for fish and plants which need oxygen to carry out metabolic functions. The Streeter-Phelps equation uses reaeration and decay constants to determine the current concentration level in the water. This equation can be manipulated to find general expressions for the time needed for the oxygen level to reach its minimum and to find that minimum concentration based on the given constants. This model indicates whether a body of water will reach unacceptable dissolved oxygen concentration levels.

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