pH is important to the quality of water because it tells how acidic or basic the water is. pH is based on a scale of 0 -14, with 7 being neutral. 0 -7 is increasingly more acidic, and 7 - 14 is increasingly more basic. If the pH level of water is below 4 or above 9, many aquatic life forms will die.

    Water can become acidic as a result of natural or human-made pollution. Acid rain is an example of this. Rain is naturally slightly acidic. When water comes in contact with CO₂ (carbon dioxide), a gas in the air, the carbon dioxide dissolves in the water forming H₂CO₃ (carbonic acid). Only a limited amount of carbon dioxide will dissolve in water, so the natural pH of rain is usually between 6.0 and 6.9.

Procedures:

· First the pH probe should be calibrated with a low and high range buffer ( buffers of 3 and 9 were used for this particular calibration). This should be done prior to testing. If calibration is not used, the reading will be accurate to +/-10% error.

· Using the Explorer and probe, set the Explorer to read pH, and place it directly into the river. Collect three data runs throughout the testing area