The Portage Diversion () (also known as the Assiniboine River Floodway) is a water control structure on the

Assiniboine River The Assiniboine River (''; french: Rivière Assiniboine'') is a river that runs through the prairies of Western Canada in Saskatchewan and Manitoba. It is a tributary of the Red River of the North, Red River. The Assiniboine is a typical meand ...

near

Portage la Prairie Portage la Prairie () is a small city in the Central Plains Region of Manitoba, Canada. As of 2016, the population was 13,304 and the land area of the city was . Portage la Prairie is approximately west of Winnipeg, along the Trans-Canada Hig ...

Manitoba Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population o ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

. The project was made as part of a larger attempt to prevent flooding in the

Red River Valley The Red River Valley is a region in central North America that is drained by the Red River of the North; it is part of both Canada and the United States. Forming the border between Minnesota and North Dakota when these territories were admitted ...

. The Portage Diversion consists of two separate gates which divert some of the flow of water in the Assiniboine River to a 29 km long diversion channel that empties into

Lake Manitoba Lake Manitoba (french: Lac Manitoba) is the List of lakes of Canada, 14th largest lake in Canada and the List of lakes by area, 33rd largest lake in the world with a total area of . It is located within the Provinces and territories of Canada, Cana ...

near Delta Beach. This helps prevent flooding on the Assiniboine down river from the diversion, including in

Winnipeg Winnipeg () is the capital and largest city of the province of Manitoba in Canada. It is centred on the confluence of the Red and Assiniboine rivers, near the longitudinal centre of North America. , Winnipeg had a city population of 749,6 ...

, where the Assiniboine River meets the Red River. During flood years such as the

2011 Assiniboine River flood The 2011 Assiniboine River flood was caused by above average precipitation in Western Manitoba and Saskatchewan. This was a 1 in 300 year flood that affected much of Western Manitoba. The flooding in Manitoba was expected to mostly involve the 20 ...

, inlet flows to the Portage Diversion control structure were measured at over . This amount of water would have disastrous effects if left to flood southern Manitoba. During the flood of spring 2011, the Portage Diversion handled roughly half the flow of

Niagara Falls Niagara Falls () is a group of three waterfalls at the southern end of Niagara Gorge, spanning the border between the province of Ontario in Canada and the state of New York in the United States. The largest of the three is Horseshoe Falls, ...

. The Assiniboine River and diking system can handle flows up to approx without a serious breach. However, many properties between Portage la Praire and Winnipeg are flooded once the flows exceed 10,500 cfs, including commercial establishments such as the KOA campground in St Francois Xavier. Over the past few years as high river flows have occurred east of Portage la Prairie, residents have noted significant bank erosion and stands of trees decades old are dying off. In recent years government policy has allowed 12,000 + cfs down the lower assiniboine towards Winnipeg causing major property and environmental damage. The diversion was originally designed to carry a volume of . Under a state of emergency in early May 2011, Manitoba authorities did extensive work by raising the dikes and were preparing to send up to down the diversion channel with bridges downstream being the determining factor in flow rat

The diversion was built at a cost of $20.5 million in 1970. The diversion control dam is 35 feet (11 m) high and 1,400 feet (430 m) long and allows storage.

Flow Rates

Below are data from years of operation of the Portage Diversion when its use resulted in a 0.5 foot or more rise in Lake Manitoba: {, class="wikitable" , - ! Year ! Peak Flow (cfs) ! Volume Diverted (acre-feet) , - ! 2011 , 34,804 , 4,770,000 , - ! 2014 , 34,100 , 2,244,000 , - ! 1976 , 26,000 , 1,420,460 , - ! 2017 , 24,700 , > 1,000,000 , - ! 1995 , 13,800 , 1,120,000 , - ! 2009 , 22,088 {{cite web, title=RED RIVER FLOODWAY OPERATION REPORT SPRING 2009, url=https://www.gov.mb.ca/mit/floodinfo/floodproofing/reports/pdf/red_river_floodway_operation_report_2009.pdf, work=Province of Manitoba, year=2009 , 932,000 , - ! 1999 , 10,500 , 914,000

References

External links

Flood control works
Assiniboine River Buildings and structures in Manitoba Flood control projects Flood control in Canada Spillways

Flow Rates

See also

References

External links