What is Water Quality?

"Water: More Precious Than Oil"

PBS Video

Water is the single most needed resource by animals on the earth. Because it is so precious, we need to treat it in desirable ways, so it will last and never run out.

The quality of water is determined by testing several parameters, usually  dissolved oxygen, biological oxygen demand, total dissolved solids, pH, temperature, fecal coliform, nitrates, phosphates and turbidity.  By testing sites along a stream or creek throughout the year to see how factors may change, a Water Quality Index may be completed.   These results can help determine the health of a body of water and its status as a "good" place for salmon or not.  Please see "procedures" section for more in depth information on testing parameters.

By studying the number and diversity of the macroinvertebrates or "water bugs" in a stream, you can also obtain a Biotic Index that helps determine a stream's water quality.  Macroinvertebrates form the basis of the food chain which feeds salmon, and many are intolerant of any pollution, while others are more tolerant.  Counting and classifying the type and number of macroinvertebrates along a given stretch of water can help with the overall analysis of that stream's water quality.

The water quality of a stream or river affects not only aquatic life forms but also humans, both in the area of recreational and personal use. It is imperative that we learn how to measure and understand the water quality standards and ways to test them.

Updated August 2003