-
Moorhead "toll bridge" (a
low-water crossing) during 2023 spring flood. The water level was at , just below the threshold for a
major flood. Floods happen in the Red River when the water level increases over the tops of riverbanks due to significant precipitation over the same area for long periods, in the forms of persistent thunderstorms, rain, or snow combined with spring snow melt and ice jam. Major floods in historic times include those of
1826,
1897,
1950,
1997,
2009,
2011, and there has been significant flooding many years in between. Geologists have found evidence of many other floods in prehistoric times of equal or greater size. These "
paleofloods" are known from their effects on local landforms, and have been the subject of scholarly studies. After the disastrous 1950 flood, which resulted in extensive property damage and losses in
Winnipeg, the province of Manitoba undertook flood prevention by constructing the
Red River Floodway. Completed in 1968, it diverts floodwaters around the city to less settled areas farther down the river. Grand Forks, North Dakota, and East Grand Forks, Minnesota, suffered widespread destruction in the
flood of 1997. 75% of the population in the former city was evacuated, and all of the latter. Many of the residential areas along the rivers were inundated and all the homes had to be destroyed. Afterward, a massive flood protection project was undertaken to protect both cities. Atashi et al. study conducted spatial analyses of the Permanent Water Area (PWA) and Seasonal Water Area (SWA), revealing a specific vulnerable section near Grafton city, located between Grand Forks and Emerson, that is highly susceptible to severe floods.
1950 flood On May 8, 1950, the Red River reached its highest level at Winnipeg since 1861. Eight
dikes protecting Winnipeg gave way and flooded much of the city, turning of farmland into an enormous lake. The city turned to the
Canadian Army and the
Red Cross and
The Salvation Army for help, and nearly 70,000 people were evacuated from their homes and businesses. Four of eleven bridges in the city were destroyed, and damage was estimated at between $900 million and $1 billion. As a result of the floods, a flood control project was constructed to prevent such damage in the future. The Red River Floodway around Winnipeg attracted some derision at the time, as some people thought it was massively overbuilt and was the then-largest earth-moving project in the world. The project was completed under-budget, and has been used for at least some flood control 20 times in the 37 years from its completion to 2006. The Floodway has saved an estimated CA$10 billion in flood damages.
1997 flood In the spring of 1997 a major flood of the Red River caused a total of $3.5 billion in damage and required temporary evacuation of towns and cities on both sides of the border. The cities of
Grand Forks, North Dakota, and
East Grand Forks, Minnesota, suffered the most damage, and most of their populations had to be evacuated. The river crested at more than above
datum. The cities worked with
FEMA and the state of Minnesota to clear the
floodplains of the river on both sides, prohibiting future housing or businesses in this area. They created the
Greater Grand Forks Greenway on both sides, which includes city and state parks, a long bike trail, and other recreational amenities. The trees and greenery help absorb floodwaters. A dike system was constructed outside this area on both sides to protect the cities from future floods. In East Grand Forks, a removable
flood wall was constructed in the downtown area so that residents did not lose their connection to the river. In Winnipeg, the flood crested at above
datum at the James Avenue pumping station, making it the third-highest flood at Winnipeg in
recorded history. It was surpassed by the floods of 1825, and 1826. The city was largely spared the fate of Grand Forks thanks to the Floodway, which was pushed to its capacity during the 1997 flood.
2009 flood In 2009 the Red River flooded in early spring. By Friday, March 27, the river at Fargo had reached the highest level in recorded history. Its discharge at that location was far in excess of normal flows. The river crested at the James Avenue pumping station in Winnipeg at above datum, making it the fourth-highest flood in recorded history. That same year there was a surprise major flood on the
Assiniboine River. In May 2011, a Manitoba-wide
state of emergency was declared in the wake of a 300-year flood on the Assiniboine River at
Brandon. Many residents had to be evacuated. == Flow rates and flood potential ==