If you are currently running or considering beginning a school based water quality monitoring program you should definitely own a copy of Mitchell and Stapp's Manual. For information on ordering, contact William Stapp .
Many factors can affect the water quality of a river system.
The conditions of a river can fluctuate periodically, so we must measure water quality periodically to look for trends. Water that is determined to be safe for one use may be unacceptable for another purpose. In fact, many water quality experts refer to their measurements in terms of a specific use. The WQI is one of the most widely used of all existing water quality indices. In a particular river reach over time, compare water quality from different reaches of the same river, and even compare water quality of different rivers.