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Indicator Type: Environmental Condition
This indicator shows the difference between the average natural flow regime and the actual flows that were recorded in the rivers during the year. Flow regimes are examined on a two-season basis, with summer open water considered as one season and the remaining seven months (late fall to early spring) considered as the other. The annual assessment is reported along with a ten-year average which is an indication of potential long-term or cumulative stresses.
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Trend: River flows were mixed in the south as compared to 2005 (some higher, some lower) while summer flows for 2006 in the north were often below normal.
The following map presents the longer-term (ten-year) Index average from 1997 to 2006:
The annual reporting shows the effects of shorter-term (one to two year) events such as an above average (wet) year or a drought. The ten-year average is meant to smooth out such occurrences in order to give a more “typical” – or average – picture of the state of the rivers.
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What does the indicator show?
After high river flows in 2005 for many southern Alberta rivers, some rivers recorded lower flows in 2006 while others continued to have somewhat higher flows as wet conditions and stored water were carried over. The longer term trend for many rivers in the south over the summer is “stressed” or “reduced outside of natural”. The Belly, Waterton, St. Mary and lower Bow rivers are the most severely affected by flow regulation and water withdrawals in the May to September (summer) season. The occurrence of long-term “stressed” rankings in the Oldman and South Saskatchewan also indicate a cumulative human impact, although perhaps not to the same degree as the other tributaries. Impacts of flow regulation are observed in the North Saskatchewan River, where net water withdrawals are not large compared to other rivers yet summer flows are much lower than natural. This is made up by water released during the rest of the year, producing flows that are higher than normal (especially in winter). Note that the Athabasca, Beaver, Clearwater, Pembina and Smoky rivers are considered essentially natural (free of significant withdrawals and flow regulation). The summer of 2006 saw many northern rivers experience below normal river flows.
The historical annual index values for individual rivers are presented below:
Click to view larger image
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Why is this indicator important?
River flow is affected by natural changes in climate and seasonal weather patterns. As well, dams and other infrastructure such as weirs and canals have affected many Alberta rivers. Large volumes of water may be withdrawn or stored for human use at certain times of year with surplus water being returned at other times of the year. This human influence can significantly alter the seasonal flows from natural patterns.
Understanding how human activities can change our rivers and aquatic ecosystems is important if we want to manage and mitigate negative impacts on the environment. Quantifying hydrologic (water quantity) change is an important first step in understanding effects of changes in other areas such as fisheries and fish habitat, vegetation – both in aquatic and in riparian areas, biology and aquatic species, erosion and deposition, and channel shape. Two key outcomes of the Alberta Government's Water for Life policy are to provide reliable, quality water supplies for a sustainable economy and that Alberta has healthy aquatic ecosystems.
This indicator does not necessarily reveal the health of the ecosystem based solely on flow patterns – a severely altered flow regime may not be “unhealthy” in the strictest definition, as it could still support a relatively productive river ecosystem. However, aquatic communities also depend on fluctuations that result from a variety of high and low flow periods. Cumulative changes causing more frequent or sustained high or low flows no longer reflect the natural regime and may cause the river to evolve into a different ecological state, along with potentially different aquatic populations and riparian communities. Ecological science generally recognizes that the maintenance and health of the existing ecosystems and populations requires maintaining aspects of the natural flow regime, including fluctuations.
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What actions are being taken?
Water for Life encourages all Albertans to improve their use of water in many ways – by being more efficient, choosing less water-intensive practices, living within existing means wherever possible – in order that we can reduce our overall demands on the resource and our footprint on the environment. Alberta Environment and the Alberta Water Council are working to facilitate water conservation and productivity plans and to establish targets for improvement for all water-use sectors.
A moratorium on applications for new licenses that withdraw surface water was recently put in place for the Bow, Oldman and South Saskatchewan River sub-basins. This will assist in ensuring that an already over-stressed system will not be subjected to further degradation from new requests and pressures. To still allow growth and economic activity to continue in these areas where water supply has exceeded the carrying capacity of the environment, the Water Act allows license transfers. Water may be transferred from existing licenses that may be underutilized or of lower value to new uses. Transferring water amongst licensees will only result in net benefits to ecosystems if the government holds back a portion of the amount and retains it for the ecosystem. Or, if the transferred amount goes toward a more “passive” use of the water where a greater portion gets returned to the river after use, the ecosystem would also benefit. However for some transfers, water not currently being used under an existing license could be freed up for another use – which could actually result in more water being taken from the river.
Even seemingly passive uses of water such as storage in reservoirs and the generation of hydropower can result in significant changes in river flow regime and potentially negative consequences for the existing ecosystems. If more water users take steps to conserve water and minimize the amount that is taken, there will be less pressure on Alberta 's rivers, lakes and groundwater.
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Links to additional information
Alberta Environment's Water Data Web Pages (including recent river flow data)
Water Survey of Canada – Archived Hydrometric Data
Alberta Environment's Water Quantity Web Pages on Rivers
Water for Life - Alberta Environment
Fact Sheets on Water Allocations and Licenses
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Feedback
E-mail the SOE Coordinator: SOE.Coordinator@gov.ab.ca or complete this short on-line questionnaire to provide your feedback: http://www.zoomerang.com/
survey.zgi?p=WEB224DW6P3E2K.
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