Increasing the drawdown rate at TransAlta's Ghost Reservoir is among the flood mitigation projects included in the latest round of making the Calgary area flood resilient as we head into the fifth anniversary of the 2013 flood that causes extensive damage along the outreaches of the Elbow and Bow rivers.

In addition, the government announced it will begin assessing three potential upstream storage options identified in the Bow River Water Management Project report of May 2017. The report recommends pursuing either a new reservoir within Glenbow Ranch Provincial Park or Morley or expanding the Ghost reservoir in addition to increasing the drawdown rate to two metres or more per day.

The assessments will include a high-level hydrology study, conceptual design of all three options, tabletop geotechnical investigation, high-level environmental scan and a stakeholder overview.

The report says it imperative for one of these measures are required to protect Calgary from serious damage, but it also recognizes all have their daunting challenges.

"The question to be addressed in the next phase of assessment is whether any of the three are simply not physically feasible or realistic to implement," states the report.

The report says it would first need to be determined if the First Nations on the Stoney Nakoda First Nations would be amenable to being compensated for a large new dam and reservoir located almost entirely on their land. A geotechnical study and policy review of the Glenbow Ranch Provincial park site would be required to determine if it's technically feasible in addition to receiving input from park officials.

The government will also study raising the Ghost dam by ~ 3 metres and/or installing a low-level outlet.

"Modifications to increase the drawdown rate would be important to the success of all the flood and drought scenarios, but either or both the other schemes for Ghost Reservoir would keep the Ghost expansion project in contention as an option for flood and drought mitigation." states the report.

The proposed drawdown of two metres or more per day is a substantial climb from what is currently deemed safe. Because of slope stability issues, the reservoir is currently lowered by no more 30cm (11.8”) daily, unless there is an urgent need.

The government is working within the timeline proposed by the Bow River basin report. Should one of the projects proceed, the report anticipates it will take a minimum of five years to prepare for construction, followed by a minimum of three years to construct and at least one additional year to commission and put into operation.

Banff-Cochrane MLA Cam Westhead says the announcements are a follow through on advice the province received last spring.

"We are always willing to take advice from these groups that are doing such good work on looking at how we can protect Albertans and we appreciate their participation in the process."

Exshaw Project announced

What may not be on the radar for Cochrane but important all the same is the $3 million project announced for flood mitigation along the Exshaw Creek. Being mountain fed, it faces the additional risk of heavy debris.

"Mountain-fed creeks receive more of debris during a flood not just water but rock and gravel and different type of aggregate that poses additional risks and threats to the community."

Sediment trap will be established for bank protection and stabilization so the creek banks are better protected from erosion.

Keeping Ghost Reservoir Low

Reduced levels at the Ghost Reservoir have now become a common site at this time of year due to flood mitigation measures. (file photo)

The Alberta government is taking control of the water levels at the Ghost reservoir until July 7 as part of an agreement reached with TransAlta. They currently sit steady at 1,187m after a drawdown that started on Apr. 1 by TransAlta. They were kept even lower two years ago at 1,185m during the same period.

Low water hinders the recreational use of the popular recreational area and the preferred level is 1,189m. At the lower level, access to the reservoir is limited and heavily impacts service providers, including Ghost Lake Recreations that in addition to managing the campground in the area also offers boat servicing & supplies, boat & RV storage and operates a marina.

Westhead acknowledges the impact but says flood mitigation is a priority.

"With the risk that flood poses it is something that we have to prioritize," says Westhead. "We absolutely respect that recreation is important to our economy and to people's well-being but the economic risk of a flood unfortunately far outweighs the recreational aspects. That's why we've worked with TransAlta to use the Ghost reservoir as part of the flood mitigation defenses."

TransAlta received $5.5 million annually from the agreement to compensate for lost revenue. None is received by Ghost Lake Recreations.