The Ghost Reservoir and a “Call to Action” for Bow River flood mitigation
Last month CRCAG provided details on the short-term agreement reached between TransAlta Corporation and the Government of Alberta. TransAlta agreed to temporarily modify the operating level at the Ghost Reservoir, thereby opening up storage capacity so the reservoir can be used for flood attenuation. The reduced level agreed for 2015 (1185m) can reduce peak flow on the Bow River by 400 m3/s, in the event of a flood.
The modified operations at the Ghost Reservoir were to be in place until early July, with the Government of Alberta possibly allowing the water level to slowly rise in late June, based on assessed flood and drought risk.
However – much earlier than expected – last week Alberta Environment and Parks instructed TransAlta to raise the water levels at the Ghost Reservoir (to 1185.9 m), due to some residents at the Ghost Lake Summer Village being unable to access water from their wells. Today, Environment and Parks issued an update stating that the Ghost Reservoir level will be raised by an additional 2 meters (to 1188 meters). Environment and Parks are continuing to closely monitor weather and river conditions, and will instruct TransAlta to modify the levels at the Ghost Reservoir accordingly.
CRCAG and TransAlta have also been in communication regarding the revised operations at the Ghost Reservoir. We’ve learned that depending on the reservoir level and how long it’s been at that level, the draw down rate varies. When the reservoir is close to full supply level over a long period of time, dam safety operations at TransAlta restrict the draw down rate to approximately 0.3 m/day. A definitive answer about how fast TransAlta could draw down the Ghost reservoir within the next week, in the event of a forecasted flood event, isn’t available.
CRCAG is aware that frustrated residents of the Ghost Lake Summer Village and recreational users of the Ghost Reservoir have been publicly vocal about the low level of the reservoir. We understand their concerns, and are working to learn more about them – and what alternative solutions are available.
It is imperative the new Alberta Government hear from you regarding the need for a long-term water management agreement between TransAlta and the Province. As conveyed at the Bow River information session at the end of May, three storage facilities with the same capacity of the Ghost Reservoir are required to fully mitigate flooding along the Bow River (Click here for the reference). We clearly have a ways to go.
If you are concerned about flood mitigation on the Bow River, please let your elected officials know. One easy way is to send the following letter, with any additions or revisions you may have, to Premier Notley, Minister Phillips, Mayor Nenshi and your MLA.
Call to Action
To: premier@gov.ab.ca, ESRD.Minister@gov.ab.ca, themayor@calgary.ca
Dear Premier Notley, Minister Phillips, and Mayor Nenshi,
At the heart of the City of Calgary is the confluence of the Bow and Elbow Rivers. A comprehensive upstream mitigation strategy involving both rivers is required to protect Calgary from the next devastating flood. I am writing to you about the Bow River – a major risk to the downtown core and many residential communities.
Although TransAlta and the Province reached a short-term agreement to revise operational levels at the Ghost Reservoir to capture potential floodwaters this year, a long-term water management agreement is imperative. I understand that water management in this Province is a balancing act, but public safety of Albertans downstream of the Ghost Reservoir and protecting Canada’s economic engine – centered along the banks of the Bow in downtown Calgary – must take precedence over recreation.
I urge the Province to continue negotiations with TransAlta to leverage additional upstream reservoirs for flood control. I implore the Province to find additional storage options along the Bow River system, to afford a minimum 1:100 year level of protection for the Bow River. The downtown core is vulnerable – meaning Alberta’s economic wellbeing is vulnerable. Failure to act is simply not an option.
Sincerely,