The flow of history


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The never-ending flood A brief history of southern Manitoba, from a hydrological perspective, up to and including the 2011 flood.

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Hey there, time traveller!
This article was published 07/01/2012 (4043 days ago), so information in it may no longer be current.

The never-ending flood

A brief history of southern Manitoba, from a hydrological perspective, up to and including the 2011 flood.


11000 BC: After the retreat of the Wisconsin ice sheet, much of southern Manitoba winds up submerged below glacial Lake Agassiz. Over the next few thousand years, this lake expands and contracts as it drains off in four directions — southeast through what’s now the Mississippi River, east through the Great Lakes, northwest along the Mackenzie River and eventually north into Hudson Bay.

Canadian solders shore up a dike protecting some homes just south of Winnipeg after water backing up from the floodway poured into the Grande Pointe area during the 1997 flood.


8000 BC: Lake Agassiz adopts the form most familiar to modern geography buffs: Its southern basin stretches across what’s now the Red River Valley, from the Manitoba Escarpment to the Sandilands. The first humans arrive in Manitoba around this time, hunting and gathering in the Turtle Mountain area.


6400 BC: The breakup of a northern Manitoba ice dam allows Lake Agassiz to drain quickly into Hudson Bay. The geologically sudden event leaves behind Manitoba’s “great lakes” — Winnipeg, Winnipegosis, Manitoba, Cedar and Dauphin — as well as a flat expanse of prairie. Over the ensuing centuries, paleo-Indian hunter-gatherers fan out across the newly exposed landscape, following large herbivores and other game. Glacial meltwaters also carve out the Assiniboine River Valley in western Manitoba and the Pembina River Valley in southern Manitoba.


5000 BC: After Lake Agassiz recedes into the “great lakes,” the Assiniboine River drains into Lake Manitoba, north of Portage la Prairie. Several different channels are carved out through what’s now Delta Marsh.


1000 BC: The Assiniboine flows east to the Red River along a channel now regarded as La Salle River. The Forks is located at St. Norbert, at what’s now St. Norbert Provincial Heritage Park.


200 BC: The first Woodland people, hunter-gatherers who may be related to the modern Cree and Ojibway, begin to move into southern Manitoba.


AD 700: The Assiniboine River carves out a route toward the Red River that closely resembles its current course.


1400s: Agriculture comes to southern Manitoba as indigenous farmers, possibly related to the modern Mandan and Hidatsa, settle around Lockport, where they grow maize, beans and squash.


1733: By the time Quebec explorer La Verendrye reaches the Red River, Cree, Assiniboine and Ojibway are firmly established in southern Manitoba.


1812: Scottish settlers come to southern Manitoba and attempt to start farming in the Red River Colony, with mixed results.


1826: Flooding on the Red River sends the entire populace of what’s now Winnipeg scurrying to higher ground on Stony Mountain and Birds Hill. In today’s measurements, the flood peaks at 36.5 feet James at Winnipeg.


1852: Another massive Red River flood peaks at 34.7 feet James, causing chaos in the Red River Colony.


1870: Manitoba joins the confederacy following the Red River Resistance, a conflict between semi-nomadic Métis and European settlers. Following entry into Confederation, the practice of draining agricultural farmland intensifies, mostly through the use of horse-drawn dredges.


1880s: The passage of the Drainage Act and the Swamp Lands Act prompts federal and provincial officials to survey most of southern Manitoba, with an eye to draining as many wetlands as possible.


1895: The Land Drainage Act passes, paving the way for even more co-ordinated efforts to rid southern Manitoba of wetlands.


1898-1919: Drainage efforts succeed in eradicating most of southern Manitoba’s largest wetlands, including the Big Grass Marsh north of Gladstone, the Boyne Marsh southwest of Winnipeg and the Tobacco Creek Marsh along the Manitoba Escarpment.


1930s: As dustbowl conditions devastate the Canadian Prairies, early conservationists begin to question the wisdom of draining wetlands and ponder restoring them.


1950: The biggest flood on the Red River since the City of Winnipeg’s incorporation inundates a third of the city, displacing approximately 100,000 people and damaging approximately 10,000 homes. The flood peaks at 30.3 feet James.

1955: Lake Manitoba swells to a then-historic height of 816.3 feet above sea level, flooding lakeside communities and farms.


1961: The province completes the Fairford River Control Structure to regulate levels on Lake Manitoba in an effort to avoid fluctuations on the shallow and highly variable lake. The aim is to keep the lake between 810.5 and 812.5 feet above sea level.


1966: Another Red River flood peaks at 26.3 feet James in Winnipeg.


1969: The Red River Floodway is completed at a cost of $63 million in an effort to protect Winnipeg from floodwaters. It uses a control structure at St. Norbert to divert a portion of the Red’s flow into a 47-kilometre canal that empties back into the river at Lockport.


1970: The province completes the 29-kilometre Portage Diversion, which carries Assiniboine River floodwaters north through Delta Marsh and into Lake Manitoba. This is designed to prevent the Assiniboine from abandoning its current channel for the lower-perched La Salle River and swamping vast areas east of Portage la Prairie during a catastrophic Assiniboine River flood.


Vancouver Sun Lake Agassiz

1972: The Shellmouth Dam is completed on the Assiniboine River in an effort to hold back water near the Saskatchewan border during floods. This creates Lake of the Prairies, also known as the Shellmouth Reservoir.


1974: At the peak of the highest recorded flood on Lake Winnipeg, water levels rise to 718.2 feet, damaging lakefront communities.


1976: Manitoba Hydro completes a series of channels as well as the Jenpeg Generating Station in an attempt to regulate the level of Lake Winnipeg to keep it between 711 and 715 feet above sea level.

1979: A spring flood on the Red River — the first major event since the completion of the floodway — peaks at 19.3 feet James in Winnipeg.


1996: A spring flood on the Red River peaks at 19.4 feet James in Winnipeg.


1997: After inundating Grand Forks, N.D., the “Flood of the Century” engulfs Manitoba’s portion of the Red River Valley, displacing 30,000 people, swamping the town of Ste. Agathe and forcing the emergency construction of the Brunkild Z-Dike to prevent the Red River from spilling into Winnipeg through the La Salle River. Even with the Red River Floodway operating, the deluge peaks at 24.5 feet James.


2005: A rare summer flood on the Red River, caused by unusual rains and saturated soil, peaks at 20.1 feet James.


2006: A spring flood on the Red River peaks at 20.4 feet James. After an initial scare, the City of Winnipeg responds effectively by employing flood-fighting lessons learned in 1997.


2009: Yet another spring flood on the Red River confounds forecasters by peaking at 22.6 feet James. Ice jams force Winnipeg to scramble to raise dikes, leading officials to amend the city’s flood manual. Downstream, ice jams cause extensive damage to homes and cottages at Breezy Point, prompting buyouts.


2010: The $665-million expansion of the Red River Floodway is completed. In October, a “weather bomb” storm damages properties along Lake Winnipeg.


January 2011: Provincial forecasters predict significant floods on the Red, Assiniboine, Souris, Fisher and Icelandic rivers.


February 2011: Forecasters adjust their predictions upwards, prompting the City of Brandon to raise its dikes along the Assiniboine River.


March 2011: Forecasters also predict flooding on Lake Winnipeg.


April 2011: Ice jams on the Red River lead to evacuations at Breezy Point, where one home is destroyed. The Red River peaks in Winnipeg at 20.5 feet James on April 9, due to ice jams. The actual crest of the Red in southern Manitoba comes in below forecasts, but flooding forecasts on the Souris and Assiniboine rivers lead to more preparations in Brandon, Melita and Souris, among other communities.


May 2011: The Red crests in Winnipeg without event, but record flows on the Assiniboine lead to sudden evacuations in Brandon, an emergency expansion of the Portage Diversion’s capacity and a frantic, military-aided effort to shore up dikes east of Portage la Prairie. The province also takes the unprecedented step of cutting a hole in the Assiniboine River dike at Hoop and Holler Bend on May 14 in an effort to prevent catastrophic flooding that would result from a dike failure further east or a breach in the Portage Diversion. Lake St. Martin First Nation is also evacuated. Defences in Brandon and along the diversion hold, but a May 31 storm damages or destroys hundreds of homes and cottages at Twin Lakes Beach and other communities at the south end of Lake Manitoba.


June 2011: People living around Lake Manitoba scramble to protect their homes, cottages and farms as the lake continues to rise.


July 2011: Lake Winnipeg peaks at 717 feet and Lake Manitoba peaks at a record 817.3 feet. The province ponders options for building an emergency channel to drain Lake St. Martin into Lake Winnipeg, in an effort to allow more water to flow out of Lake Manitoba.


August 2011: Construction begins on the $100-million Lake St. Martin Emergency Channel, which allows the lake to drain into Big Buffalo Lake and the Dauphin River on the way to Lake Winnipeg.


November 2011: The Lake St. Martin Emergency Channel opens.


December 2011: Approaching Christmas, 2,778 Manitobans remain evacuated due to flooding. The province pegs the cost of the 2011 flood at $945 million, including mitigation, compensation and the emergency channel.


Sources: The Geography of Manitoba: Its Land and Its People, Wet Prairie: People, Land and Water in Agricultural Manitoba, and Free Press files.

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