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Detailed review of dams and reservoirs coming

A special review of the province's water management infrastructure and current operations is underway, but just how much of the ensuing report will be made public is unknown at this point.
The provincial government has ordered a review of the Rafferty Dam spillway to ensure there was no damage during this year's flooding.

A special review of the province's water management infrastructure and current operations is underway, but just how much of the ensuing report will be made public is unknown at this point.

"We will be filing our inspection report to the minister (Dustin Duncan, minister responsible for the Saskatchewan Watershed Authority) in September. What we send to him won't be public, but I expect a statement will be made by his office shortly after and our inspection details are public documents," said Dale Hjertaas, executive director of policy and communications for the Watershed Authority.

"We will have rolled up all the information on the dams by the end of September, but I expect some individual reports may be filed later," he added.

Duncan had noted on Aug. 2 that he had directed Watershed Authority officials to take additional measures to review the impact record runoff and rainfall may have had on water management structures in the province. He noted the Saskatchewan people depend on them for flood prevention and mitigation as well as irrigation, drinking water and recreational activities. The study would reveal any rehabilitation needs that have surfaced following two years of very high water volumes.

Additional work in four main areas was ordered that included special inspections on 19 dams that experienced unusually high water flows or reservoir levels in 2011. There was a call for a special review and recommendations of operations at Rafferty, Alameda, Boundary and Gardiner Dams.

The other two areas where special attention was warranted had to do with inspection findings and ongoing monitoring and assessments to identify long-term infrastructure renewal needs of the dams and a recommendation for upgrades to the authority's dam-safety program.

The extra measures, it was pointed out, were precautionary steps due to the extreme water levels experienced this year. SaskPower will conduct inspections and reviews of its dams, including Boundary.

Hjertaas said the Authority will report to Duncan with observations and recommendations resulting from the additional inspections and the work undertaken during the review.

When contacted by The Mercury on Aug. 3, Hjertaas said he did not know whether the review process would include consultation with valley residents in southeast Saskatchewan where the flood waters bore the most impact.

"We'll be recommending a process, then a review. We don't know yet whether that will include consultation with North Dakota officials and residents since they contributed to the construction of Rafferty Dam," he added. How many and the specific talents of outside experts that might be called on to assist with the review, is also unknown at this early stage of the process, the executive director said.

An additional concern might be the upcoming provincial general election in early November since it is expected that by early October there will be instructions for a lock down on publishing and public consultations to adhere to regulations surrounding the Elections Act.

As to whether Rafferty's reservoir will be drained below full supply level this fall and winter, Hjertaas said that the Authority has to adhere to the international agreement they have with the United States and levels have to be maintained at certain points to meet the agreement requirements.

"In other words we need to supply water, so you have a tradeoff situation. If we end up with five years with no or little water, it becomes a problem, or we have limited flood protection, that's a problem too. Rafferty was built to be maintained at full supply levels with an additional 3.9 metres for excess or flood water storage," said Hjertaas.

"So the key point for Rafferty is the draw down in anticipation of the coming season and that's a winter decision. We draw down in anticipation and we would be criticized for a heavier than needed draw down. We can lower the flow rate now, in fact it came down from 35 cubic metres per second to 15 cubic metres per second today (Aug. 3) so Rafferty is slowly being lowered to full supply level and then we'll carry on at that level until we see what is anticipated heading into winter. So, to answer your question, Rafferty will definitely continue to be lowered until it hits full supply level and we expect normal operations perhaps until February, but the hydrologists will decide whether we need to step up the outflow now and perhaps open it again in the winter and it will need to be lowered to meet spring targets," Hjertaas added.

The general strategy, he explained, is to keep the dams at full supply level to the end of summer and then conditions will dictate whether or not there needs to be a deviation from normal operations.

"This summer, by June 18 and 19, the Souris Valley was the biggest problem. The Qu'Appelle Valley has been a major trouble spot for the past few years too and the lakes there are still at high levels. Last Mountain Lake is now draining down a bit. Cumberland House was another problem area but at least we could foresee that one a little in advance because the Alberta rains caused that problem and we had time to prepare. We also got levels at Gardiner Dam down before the floods and yet, some regions still required a lot of diking and sandbagging and road protection. There were a lot of dikes and berms built all over the province but still, there were damages as you well know. There were still problems at Cumberland House and downstream from Gardiner and in the Qu'Appelle but the Souris situation was the worst and then, on top of that, there was this unusual non-river event around Benson and Lampman with flood damage and protection measures and other problems too. A similar situation cropped up near Martensville," said Hjertaas, outlining the fact it has been a summer of action and reaction for all concerned.

Hjertaas said that in referring back to the Rafferty reservoir situation, usual circumstances would mean that there is a large flood protection capacity behind this dam because of the 3.9 metre margin and the fact that the reservoir covers a large geographical expanse, but even at that, it was a struggle to try to get it down to full supply level heading into this past spring which eventually led to the devastating decision of having to release water from the spillway for the first time ever. It was noted that the 2011 runoff volume could have completely filled the Rafferty reservoir twice.

Alameda reservoir reached a record level of 566.6 metres and operated above full supply level for an unprecedented 100 days from mid-April to Aug. 1.

A 2.5 inch rainstorm between June 23 and 25 added to an already saturated watershed which, in turn, led to record flooding on the Souris River beyond any previously recorded water volumes.

Water levels on the Rafferty rose six metres, moving from a point that was 2.5 metres below full supply level to the maximum allowable flood supply level of 554.4 metres.

Outflow from the spillway at Rafferty alone reached 508 cubic metres per second, shattering any previous release records and with the additional flows being released from Boundary Dam reservoir at the same time, the combined flow rate into the valley measured 770 cubic metres per second during the peak release period.

The Rafferty Dam was operated above its full supply level for 100 days from April 15 to Aug. 1.

The Authority said they monitor the extreme consequences dams daily. That list includes Gardiner, Qu'Appelle, Rafferty and Alameda. They conduct weekly inspections of these facilities plus they work with SaskPower to assess high water impacts on Boundary Dam on a regular basis.

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