SPOTLIGHT on the Athabasca: principle to practice – low flow protection in water management

Written by Mathieu Lebel, Advisor, Water Management & Rob Powell, Senior Officer, Priority Conservation Programs
This is part of a special WWF blog series exploring the Athabasca River’s unique ecosystem and water management, and most importantly, how we can ensure its healthy future. This is the third blog in the series.
A key focus in water management is preparing for and responding to infrequent but inevitable high and low flow conditions, in other words floods and droughts. Floods in southern Alberta and Toronto this spring and summer certainly brought this to the fore and these events are prompting additional management actions to mitigate and adapt to future floods. Equally as important are the approaches to prepare for and respond to low flow conditions including water storage, conservation, demand management, and a system for allocating scarce water resources among multiple social and economic water uses and users. At the same time, central to sustainable water management is the protection and restoration of environmental flows and the benefits they provide. Not surprisingly, with competing demands and limited supply, the low flow period is often a central component and challenge in water management planning and decision-making. This is evident in rivers like the lower Athabasca in Alberta.
Increasingly, the implementation of an ecosystem base flow, or cut-off flow, is recommended during low flow conditions. While this principle is well supported including in the context of the lower Athabasca River, translating environmental flow protection more broadly into water management practice is challenging. Why is this so hard and what can be done to accelerate the protection of environmental flows? These are the general social and scientific questions scientists, water managers, and all those with an interest in healthy rivers are working towards.

Fall foliage in the Athabasca River Basin.
Fall foliage in the Athabasca River Basin. © Garth Lenz / WWF-Canada

The exact threshold to set an ecosystem base flow for any river may be uncertain even when detailed site-specific studies have been conducted. Integrating improved knowledge as it becomes available is important, but in the interim setting an ecosystem base flow becomes a matter of how to apply precaution and the best available information.
Decisions on environmental flows are driven by the range of often competing social, economic, and environmental interests for the lower Athabasca as they are for any given river. Implementation may be enabled or constrained by water policies and laws, among other factors such as political will. Ultimately though, the issue of environmental flows comes down to what is desired for our rivers, and the public has a critical role in this process. The ecosystem base flow component of environmental flows is perhaps a unique case in this regard as it may involve a clear shift in traditional water management practice: when flows drop to or below this threshold, the remaining water in the river is reserved to sustain aquatic ecosystems rather than to continue to be diverted for human use. During these conditions, which could be expected to occur anywhere from 20% of the time to once-in-100 years depending on where the threshold is set, water users would be required to use an alternative water source or stored water to meet their requirements. Aquatic ecosystems do not have these options, and an ecosystem base flow helps ensure their water requirements are protected.
With multiple social, economic, and environmental objectives, the issue of environmental flows ultimately comes down to what is desired for our rivers
With multiple social, economic, and environmental objectives, the issue of environmental flows ultimately comes down to what is desired for our rivers © Mathieu Lebel

While determining and implementing plans to maintain environmental flows will continue to encounter scientific and social challenges, there are an increasing number of examples demonstrating their value in protecting and restoring rivers and other waters around the world. Within Canada, water management that is consistent with the ecosystem base flow concept is also emerging in some regions. For instance, in response to low flow conditions in 2009, the British Columbia Ministry of Environment ordered the temporary curtailment of water use on the Nicola River to protect the kokanee salmon population.
The inclusion of an ecosystem base flow in a water management plan provides increased certainty that the aquatic ecosystem will be protected during low flow conditions, and also provides water users with the opportunity to prepare for these conditions.  For the lower Athabasca River, the development of an updated water management plan is an occasion to move an ecosystem base flow from principle to practice and demonstrate a commitment to sustainable water management, and sustaining aquatic ecosystems, into the future.