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Hey there, time traveller!
This article was published 12/3/2013 (2678 days ago), so information in it may no longer be current.
Flood season approaches and the victims of the great flood of 2011 and 2012 are understandably apprehensive. The Portage Diversion is scheduled to open this spring, creating renewed worries for everyone from Lake Manitoba to Lake Pineimuta, Lake St. Martin and the Dauphin River. The good news is that, with a bit of luck, flooding will be minor and local and Lake Manitoba and Lake St. Martin are expected to stay inside their normal operating range.
Now, nearly two years after the beginning of the great flood that caused this apprehension we can ask the question: Are we better prepared now to prevent future flooding?
According to Steve Ashton, minister of infrastructure and transport and emergency services, we are. He points to the construction of the emergency channel out of Lake St. Martin as a significant achievement. And it was.
The emergency channel runs 6.5 kilometres from the east side of Lake St. Martin into Big Buffalo Lake, and from there water runs downhill into Lake Winnipeg. It was built in record time in the middle of nowhere. Work crews were brought in by boat and helicopter, and heavy equipment by barge. Its construction involved moving 1.4 million cubic meters of peat and till in just 60 days and it began flowing on the Nov. 22, 2011.
It was also built for far less than its originally advertised cost of $100 million. A freedom of information request by the Rural Municipality of St. Laurent revealed that the actual cost to be less than $40 million, a drop in the bucket of flood costs to the provincial treasury that have reached $1.2 billion and are still rising.
The emergency channel did its job. It relieved a bottleneck in the system that normally restricts winter outflow from Lake Manitoba. The prospect of ice jamming on the Dauphin River and flooding of Lake St. Martin normally restricts outflow from Lake Manitoba's sole exit -- the Fairford Water Control Structure -- to a relative trickle from December to April. With the emergency channel in place, the FWCS was wide open in the winter of 2011-12 and both Lake Manitoba and Lake St. Martin fell substantially.
But the emergency channel was closed in November 2012 after flood levels on Lake Manitoba and Lake St. Martin had abated. Under current operating policy, it will not open again unless emergency conditions return.
Does this channel leave us better prepared to cope with future flooding arising from the use of the Portage Diversion? In the short term yes, in the long term no.
Lower lake levels obviously mean a lower risk of flooding in the near term. But over the long term, those lake levels would have subsided naturally.
The real challenge is dealing with water artificially diverted into Lake Manitoba from the Portage Diversion. And for that, the emergency channel is on the wrong lake and operates in the wrong season. It allows us to dump more water in the winter following a flood. Thus, the primary value of the emergency channel is to allow us to clean up faster after a disaster occurs, not to prevent a new disaster from occurring.
The problem that existed at the beginning of 2011, and that still exists today, is that the outlet from Lake Manitoba is too small to cope with extra inflow from the Portage Diversion.
In most years the natural inflows and outflows on Lake Manitoba roughly balance. In years of higher precipitation and runoff, natural inflows exceed the outflow capacity through the FWCS and the lake rises in spring usually between six inches to 18 inches. At this point there is no spare outflow capacity: when the Portage Diversion opens, that water has nowhere to go.
As a consequence, in 2011 Lake Manitoba rose four feet in three months. It was worse on Lake St. Martin, where the lake rose five feet. These levels exceeded the highest water levels seen on both lakes since we started keeping careful records in the early 20th century. In July 2011 Lake Manitoba was a foot higher than its peak in 1955; Lake St. Martin was three feet higher than its 1950s levels.
The flooding of 2011-12 on Lake Manitoba and points downstream was largely due to the operation of the Portage Diversion. The diversion is a water control structure that protects Manitobans east of Portage la Prairie including Winnipeg. It was completed in 1970. That its construction could create later problems on Lake Manitoba was obvious then. In the 1970s the province considered the creation of an expanded outlet to Lake Manitoba as a potential solution.
Had such an outlet existed in 2011, the flood damage would surely have been at least $1 billion less than its current $1.2-billion cost -- a cost that has been added to the provincial debt and for which we will continue paying for a very long time.
The political decision was not to proceed because the forecast benefits fell short of the construction costs. This decision was, in retrospect, disastrously wrong -- it was our $1-billion mistake.
With an expanded outlet to Lake Manitoba and a corresponding outlet to Lake St. Martin downstream, the flood waters of 2011 could have easily, safely and cheaply been moved to its natural destination of Lake Winnipeg.
For those around Lake Winnipeg, the effect would be minimal. All the flood waters artificially diverted into Lake Manitoba in 2011 represent about a nine-inch rise in Lake Winnipeg.
In the coming months there will be much discussion about flood mitigation options on the Assiniboine basin and on Lakes Manitoba and Lake St. Martin. These discussions will again revolve around the costs and benefits of new flood works.
What doesn't fit neatly into this equation is the human cost in wrecked lives and ruined livelihoods, the agony and despair experienced by the thousands of flood victims. For many this continues to this day.
It was disastrously bad for the permanent and seasonal residents around Lake Manitoba. But it was worse for the First Nations communities downstream, alongside Lake Pineimuta, Lake St. Martin and the Dauphin River.
For these communities the problems did not just begin in 2011, but extend back a half century to the construction of the Fairford Water Control Structure. Lake St. Martin is shallow and much smaller than Lake Manitoba. Small changes in water level on the big lake cause large changes in water level on the small lake. The problem is both too much water in flood years, and not enough in dry years. And the problem grew considerably with the construction of the Portage Diversion. That made life for the people especially on Lake St. Martin much worse.
The First Nations communities were the first affected and will be the last to recover. The second anniversary of the evacuation of the Lake St. Martin First Nation now approaches and we still do not know when or even where they will go home. They are among the many still suffering from the after effects of the great flood. The job ahead is to ensure this human tragedy never happens again.
Scott Forbes is an ecologist at
the University of Winnipeg.
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