What information does a water quality index convey?
Many water quality variables (e.g., acidity, fecal coliforms, dissolved oxygen) are compared to water quality guidelines or site-specific objectives. The results of those comparisons are combined to provide a water quality ranking (good, average, poor) for individual water bodies. The actual variables used are those which are important for the particular water body. The importance of site-specific objectives and their selection are crucial to obtaining the most meaningful results from the CCME WQI. The index can incorporate CCME water quality guidelines or guidelines from other jurisdictions when site-specific water quality objectives are not available, so that comparisons can be made for different water uses (e.g. aquatic life, drinking water, and recreation). The advantages of an index include its ability to represent measurements of a variety of variables in a single number, its ability to combine various measurements in a variety of different measurement units in a single metric an
