The CCME Water Quality Index (WQI) is similar to the UV Index we check before spending the day in the sun, or an air quality index in smog season. It provides a snapshot of water quality.

Water quality experts in Canada look at many different kinds of information that is quite complex and technical. The WQI provides the non-expert with a way of understanding the overall water quality. The number produced by the Index means that water quality can be compared from one community to another.

It is important to remember that the WQI alone should not be used to make hasty decisions to clean up a water body. For instance, should an impairment to the water quality of a system be noticed, this is an indication that further investigation is needed into the potential problem area.

Rankings are provided for individual water bodies of excellent, good, fair, marginal or poor. The CCME WQI includes evaluation of many of the different items that are used to evaluate water, such as acidity, fecal coliform, dissolved oxygen and so on.

The CCME Water Quality Index is a means to provide consistent procedures for Canadian jurisdictions to report water quality information to both management and the public. It was developed by a sub-committee established under the CCME Water Quality Guidelines Task Group.

Other indices are also used by the different governments.

There are three documents that pertain to the CCME WQI:

• A technical report describing how the index was developed.
• A user's manual outlining how to use the index.
• A program that calculates index values based on information input by the user.

CCME National Water Quality Index Workshop Report, CCME Water Quality Index - A path forward for consistent implementation and reporting