A recent Alberta government report indicated that water quality on four of Alberta's six rivers declined in 2005-2006 from previous years. Media attention spurred as a result of this report raised two questions: To what degree did stormwater runoff during the 2005 flooding play a role in this decrease of water quality? What is the Alberta's Water Quality Index (WQI) and what does it tell us — and not tell us — about the state of Alberta's rivers?

The Alberta government's target is that all rivers in Alberta have good to excellent water quality. The Government of Alberta's annual report, Measuring Up, compares actual performance results to desired results set out in the government's business plan. Measuring Up commented on goal 11 — the high quality of Alberta's environment will be sustained.

This report shows a decrease in water quality for 2005-2006 in the Oldman, Bow, Red Deer, and North Saskatchewan River basins. According to the Government of Alberta, this poorer water quality can be attributed to natural and human factors but most significantly higher-than-normal rainfall. Heavy rainfall particularly in June 2005 washed a greater proportion of contaminants on the land into water bodies than some other years. While heavy rainfall is natural, the presence of contaminants on land is often not. Specific factors include "flow volume, degree of development in the basin, point source effluents that discharge into rivers, and non-point sources of runoff (such as from agricultural fields)" (GOA 2007).

How does the Alberta government measure water quality?

To gather a simple "snap shot" of Alberta's rivers, Alberta Environment uses a measurement tool called the River Water Quality Index. It compares the state of a river over time and compares rivers within Alberta. It combines the complex biological and chemical attributes of the river into a single value which provides a simple overall view of annual water quality data. This index combines measured values for nutrient, metal, pesticide, and bacteria concentrations in the river water at different locations on each river. The value for the metals category uses up to 22 variables measured quarterly. The nutrients value uses 6 variables measured monthly. The bacteria value uses 2 variables also measured monthly. And the value for pesticides uses 17 variables, which are measured four times during the open-water season (May through September) (AENV 2007).

Be aware: Alberta's Water Quality Index can be misleading

Although the River Water Quality Index provides a quick overview of a river's water quality, it is a very general snapshot that can be used in such brief reports as Measuring Up. While the formula used is partially based on the CCME (Canadian Council of Ministers of the Environment) Water Quality Index, the method for compiling the overall Index is tailored to Alberta. In general, the index formula is based on three questions that relate to water quality objectives: 1) How many variables do not meet objectives? 2) How frequently do measurements not meet objectives? 3) By how much do measurements not meet objectives?

To assure our watersheds are protected, it is more important to gain site-specific information throughout a watershed including small streams, tributary rivers, and the main stem rivers. The Bow River watershed provides an example of why the government's snapshot approach could potentially mislead the public.

Water quality in Bow River watershed

The Alberta River Water Quality Index report for 2005-06 indicates that the Bow River upstream of Calgary (Cochrane) is "excellent", where guidelines are always met. Downstream of Calgary (Carseland) the Bow River water quality was rated as "good", where guidelines are occasionally exceeded (usually by a small degree) and the threat to water quality is considered minimal. This report states that downstream water quality conditions have improved because the City of Calgary has improved water treatment (e.g. full disinfection beginning in 1997). But nutrient and pesticide concentrations remain higher downstream of Calgary (AENV 2007), likely due to agriculture activities and urban discharges from stormwater and wastewater plants.

But a closer look at individual results for specific water quality monitoring stations gives a more accurate picture. For example, water quality for the Elbow River, where it joins the Bow River, is rated as "good" overall but only "fair" for bacteria concentrations (AENV 2007). A 2004 study indicates that Elbow River's water quality is deteriorating upstream of the Glenmore Reservoir, a central source of Calgary's drinking water and the only source for Calgary until 1972. Levels of turbidity, dissolved phosphorus, and coliforms have all increased over recent years (Sosiak and Dixon 2004).

Further downstream below Bassano Dam, where on low flow years one can walk across the Bow River, water withdrawal by Eastern Irrigation District can have a significant impact on both habitat and water quality. Less water means less contamination can be diluted and assimilated by the river. Sources of contamination come from upstream sources and runoff from local livestock operations (BRBC 2002). Irrigation return flows and sewage also affect the river. Due to shallow water during low flow periods, water temperature increases. Higher water temperatures decrease dissolved oxygen - and, if high enough, can kill fish and other aquatic life (BRBC 2002).

How is water quality regulated to protect aquatic life and human health?

To test if water meets certain standards, scientifically determined water quality guidelines provide limits to what can be in the water. Water quality guidelines vary based on the intended use of the water - swimming and recreation, livestock watering, irrigation of crops, ecological health, and so on. Alberta's guidelines have been established to protect aquatic life, agricultural uses (irrigation and stock watering), and recreational and aesthetic purposes. Requirements to protect aquatic life tend to be most stringent. Water from any water body is assumed to not be drinkable without treatment because there is always the chance for naturally occurring bacteria or protozoa (AENV 2006b).

National guidelines provide targets for aquatic ecosystem protection. Canada has a series of guidelines for specific water-use purposes, such as aquatic ecosystem protection, agriculture, and so on. They are intended to be applied across Canada in a manner appropriate to the local conditions, such as assimilative capacity and sensitivity of endangered species and habitat, of the specific water body (EC 2004). Modification of the guidelines is not meant to incorporate anthropogenic effects but acts to improve degraded systems and reflect natural conditions.

Each province chooses whether and how it will incorporate the national water quality guidelines into its water management and sometimes its legislation. Alberta generally aims to meet Canadian Water Quality Guidelines.

What is measured?

Measuring water quality involves a number of measurements and factors. Measuring the multiple characteristics of a river or lake is important to be able to take specific action to correct problems.

Water quality is measured based on biological, chemical, and physical characteristics. Biological characteristics of a water body are based on types and quantity of aquatic plants, animals, bacteria, and protozoa. Chemical characteristics include types and amount of nutrients, minerals, metals, oxygen (and other dissolved gases), and organic carbon. Physical characteristics include water temperature, colour, turbidity, and suspended solids (AENV 2006).

A number of natural and anthropogenic factors affect water quality. Hydrology, vegetation, and geology naturally affect water quality. Release of treated municipal wastewater and stormwater, agricultural and industrial effluent, and many other land-use activities affect water quality as point (single point of discharge) or non-point (dispersed points of discharge) sources. Water quantity also affects water quality. The less water present in a stream, the less the stream is able to dilute and assimilate pollutants (AENV 2006a).

Sources

Alberta Environment (AENV). 2006a. Surface water quality.

Alberta Environment (AENV). 2006b. Guiding Principles for Water Quality and Aquatic Ecosystem Monitoring.

Alberta Environment (AENV). 2007. Alberta River Water Quality Index.

Bow River Basin Council (BRBC). 2002. Reach 6, 7, and 8.

City of Calgary. 2007. Water Quality Report, 2006. www.calgary.ca/waterservices

Environment Canada (EC). 2004. Canadian water quality guidelines.

Government of Alberta (GOA). 2007. Measuring Up.

Sosiak, Al and Jamieson Dixon. 2004. Impacts on Water Quality in the Upper Elbow River. Alberta Environment and the City of Calgary.