WINNIPEG — Lake Manitoba has reached flood level, again. Lakeside communities have not yet recovered from the disaster of 2011-12 and now are set to do it all over again. The provincial government’s solution to flooding on Lake Manitoba seems to be this: Add more water.
Heavy use of the Portage Diversion over the last two years has left the lake with no freeboard to absorb more inflow. Now, with record rains over the last week in Saskatchewan and western Manitoba, the province is dealing with rising Assiniboine River flows by preparing to run the Portage Diversion full tilt.
People who live along Lake Manitoba are being sacrificed to protect communities on the floodplain of the lower Assiniboine. Again.
Assigning blame now is pointless — there will be plenty of opportunity in coming months and years to do that in the courts and at the ballot box. More important right now is to do everything to minimize the coming damage.
Quite simply, Lake Manitobans should prepare for a scale of damage similar to that on May 31, 2011, when the lake sat at 815.4 feet.
The immediate problem is a slug of water headed down the Assiniboine River. Its flows are now forecasted to reach 45,000-47,000 cubic feet per second (cfs) at Portage on July 13. The province has announced flows on the lower Assiniboine will increase to 15,000 cfs. The rest has no place to go except down the Portage Diversion. The diversion will run well above its design capacity of 25,000 cfs in the next two weeks with 30,000-32,000 cfs being sent to an already flooded Lake Manitoba. That flow rate will cause a rise in Lake Manitoba of six inches every 10 days. There is now no escaping another massive flood on Lake Manitoba.
Lake Manitoba currently sits at about 814 feet, its official flood level. That is a rough estimate, as high winds over the last few days make assessing the lake level difficult.
Lake Manitoba now seems almost certain to reach 815 feet — and probably well over that — before the end of the month. That is roughly the level of the lake when the disaster that inflicted more than a billion dollars worth of damage struck in 2011.
Lake Manitobans need to prepare for the worst. The afternoon of May 31, 2011, serves as a guide. That day the lake rose nearly 1.5 metres along its eastern shoreline during an intense windstorm. People should make preparations with that lake level in mind.
Along the lakeside, everything that can be moved should be moved. What can’t be moved should be sandbagged. Geotubes need to be installed in front of exposed properties. Expect power to be lost, so keep the contents of fridges and freezers at a minimum. Be especially alert during windstorms, because road access can be lost quickly.
One would hope the province will move the equipment and personnel into place expeditiously to help with the much-needed flood preparations.
Lakeside communities cannot afford another prolonged disaster such as the ones that occurred in 2011 and 2012. Local businesses have withered and died in the aftermath of the last flood. Another extended flood will be the death knell for those still hanging on. One need look no further than Gratton’s General Store, the only grocery store in St. Laurent. It closed this past spring. A for-sale sign is posted on its door.
Our provincial government takes credit for solving the last flood by building the “emergency channel” on Lake St. Martin. This did not solve the problem on Lake Manitoba. It lowered the level of Lake St. Martin, which is useful.
But the construction of the channel was a bit like unclogging a basement drain to deal with a bathtub overflowing on the main floor. It minimizes damage in the basement but doesn’t really help with the flood upstairs.
The stated reason for building the emergency channel was to allow the sole exit to Lake Manitoba — the Fairford Water Control Structure — to remain open during the winter months without flooding Lake St. Martin. It was normal policy to reduce flows at Fairford over the winter to prevent flooding of Lake St. Martin due to a buildup of frazil ice on its exit, the Dauphin River.
But given the evacuation around Lake St. Martin had already occurred, the Fairford Water Control Structure would likely have remained wide open with or without the construction of the emergency channel: There was no one left to flood downstream. So it did help solve flooding on Lake St. Martin. But on Lake Manitoba? Not so much.
The solution is obvious to all. A new outlet is needed from Lake Manitoba to release much more water.
The engineers have now had three years to evaluate the options. There are several, but the most feasible seems to be a new channel near Fairford draining from Lake Manitoba into Lake St. Martin.
The PST increase was justified by the need for new flood infrastructure. So start digging the ditch. Make it wide and make it deep. But this time consult a map first, and build it on the right lake.
» Scott Forbes is an ecologist at the University of Winnipeg and has owned property on Lake Manitoba for the last 15 years.
» This column was also published in a recent edition of the Winnipeg Free Press.
Republished from the Brandon Sun print edition July 5, 2014