GRAND FORKS — Since the Flood of 1997, Grand Forks and East Grand Forks have had six major floods.
Floods above 46 feet are considered a major flood in Grand Forks, and in recorded history, the Red River has passed 46 feet 10 times, meaning a majority of major floods in Grand Forks have been in the last 25 years.
A system of floodwalls and levees completed at the end of 2006 have lessened the impacts of spring flooding in Grand Forks and East Grand Forks, but even with new flood mitigation measures, city leaders kept flood levels the same. At the Grand Forks gauge, 28 feet is considered a flood, 40 feet constitutes a moderate flood, and 46 feet is a major flood.
No flood since 1997 has come near the 1997 flood’s record crest of 54.35 feet. The only other flood with a crest above 50 feet was in 1897, when it crested at 50.2 feet, but 2011 came close, cresting at 49.86 feet on April 14.
Despite being third for height, the flood in 2011 was the second largest flood in Grand Forks in terms of flow , measured in volume per second, with a flow of 90,296 cubic feet per second at its crest. The 1997 flood flowed at 137,000 cubic feet per second at its crest, and the 1987 flood had a flow of 85,000 cubic feet per second.
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In 2009, the predicted crest level was 52 feet on March 22 after an early March snowstorm. The river ended up cresting at 49.33 feet on April 1, and along with being a high flood, it was also a long one. The river passed the flood stage of 28 feet on March 22 and stayed above 28 feet until May 14, according to United States Geological Service data, making for a 53-day long flood.
The seventh highest flood was in 2006. Floodwalls were still under construction when the river peaked at 47.93 feet, but according to ICS Inc., temporary flood protection was put into place during flood events.
The most recent major floods were in 2019 and 2020, which had back-to-back major floods, cresting at 46.94 feet and 47.70 feet respectively. 2020 was the eighth highest flood on record, and 2019 was the 9th highest flood.
The 10th highest major flood in Grand Forks was in 2010, and it was also the earliest major flood. The river crested at 46.09 feet on March 20. The next March flood on the National Weather Service list of historic crests for the Grand Forks gauge is the 27th highest on the list — the flood of 1920, which crested at 41 feet.
Amanda Lee, service hydrologist at the National Weather Service office in Grand Forks, says the heightened frequency of major floods in the last 25 years are likely the result of the relative wet cycle in the region that started in the early 1990s, but many factors contribute to flood levels.
“Spring flooding in this basin is just so intricate and based on so many different variables: precipitation the preceding fall, base stream flow of the rivers before they freeze up, frost depth as we move towards spring, the winter snowpack and amount of water in that snowpack, the spring thaw cycle, and any spring precipitation, especially rain, and the timing of that precipitation during the melt,” said Lee.
She says precipitation is the biggest wild card of the ingredients that go into a flood. Take this spring for example — winter was snowy, but near the end of February and throughout March, there was very little precipitation. At the same time, snow started melting.
“Things could have turned out much differently flood-wise if that period had been very wet rather than dry, especially if decent rainfall occurred at the same time the snow was melting,” said Lee.
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According to Al Grasser, city engineer for Grand Forks, flood mitigation measures like the floodwalls, the Greenway and English Coulee diversion channel not only lessened flood impacts, but made flood preparation easier and quicker.
He says before the flood mitigation measures were put in place, flood preparation had to start much earlier and took more resources. For years when the forecast showed potential for major flooding, the city had to contract companies to haul in clay, line up volunteers for sandbagging and find places to store sandbags.
Grasser explained that in a year like this year, where early forecasts predicted a worse flood year than actually happened, mitigation measures in place saved the city and people of Grand Forks time, effort and money.
“We don’t have to react as soon and we don’t have to line up as many resources,” he said. "When we can do that work with in-house city staff, we can react very quickly.”
Although major flooding has been more frequent in the last 25 years than ever before in recorded history, Grasser says in Grand Forks now, there is a level of “psychological comfort.”
“A lot of those years when we were in that wet cycle, the numbers tended to keep ratcheting up on us, and I think now feel safe and comforted behind our boundaries,” he said. “We’ve eliminated that source of angst that otherwise would permeate this time of year.”
