Bow River Flows – How Are They Controlled

The Bow River fishery needs a constant supply of cold clean water to sustain its future as a world recognized “Blue Ribbon” trout river.

The management of water flows is controlled by the Province of Alberta within long standing agreements with TransAlta who control the hydro-electric dam infrastructure above Calgary, the City itself and the irrigation districts downstream. On a weekly basis each of these parties meet to establish the water release rates through the upstream storage capacity to meet demand for water and federal minimum flow legislation. Water will be released or held back within the Bow River Basin storage capacity to meet projected demand.TransAlta Res Storage

Historically the need for consistent Bow River flows gave rise to a very productive trout fishery, but in recent years, floods, droughts and modification to the Bow River water management protocol have given rise to extreme changes in flow rates. Often as much as 50% drop or increase in flows within a very short time period as illustrated in the following flow chart.

Calgary Flws Weel jul 14

Why have we seen these dramatic changes in river flow in recent years? Principally due to a modified Bow River Water Management Protocol that empties Ghost Reservoir upstream of Cochrane in May to aid in potential flood relief to the City of Calgary and once the city’s exposure to this threat is reduced the reservoir is returned to normal operation capacity by the middle of July.Ghost Res July 20

Equally important is the containment of  rapid changes in river flows below Ghost hydro-electric power plant where flows can either increase or decrease rapidly due to power demand. This is achieved by the cushioning effect of the Bearspaw Reservoir.

Cochrane Flows Week Jul14

Unfortunately there appears to be a breakdown of the operation of the water management protocol for the week of July 15, 2018 where the extreme changes in flow destroyed the fishing downstream of Calgary and may have impacted the survival of the fishery itself.

Bow River Trout Foundation has been documenting the modified water management protocol for some time with meeting planned with Alberta Environment & Parks at the end of July to discuss potential changes that will enhance the fishery. But because of what we had seen this week we approached TransAlta with our concerns. The following documents our request and the response. Today we have seen a return to a more normal consistent discharge from Bearspaw that we hope will continue.
To TransAlta:
The rapid drops and increase in Bow River flows we have seen this week as illustrated in the attached weekly flows at Calgary has destroyed the fishing and may well have long term impact on the future of the Bow River as a world class fishery.  There is also evidence to suggest that the survival of trout can be compromised by flow variations of the nature that we have seen this week. It appears that Bearspaw Reservoir water management protocol is unable to cushion the fluctuations in water discharge from power generation at Ghost Reservoir.There is need to correct this mismanagement of our water resource before we see further depletion to a very vulnerable trout population that has seen significant declines recently. We trust that TransAlta recognizes the urgency to make changes to the Bow River water management operation procedures as soon as possible to alleviate further damage to the fishery.

The Response:

Bow River water level fluctuations over the past days are a combination of several factors, including extra generation due to hot weather and additional water inflows into Ghost Reservoir.  This type of wide fluctuation is outside the norm. We have taken steps to manage and correct these unusually large fluctuations and expect water levels to return to more moderate levels in the next few hours. We will provide updates as necessary.

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