FARGO — Those frequent sandbag scrambles that have plagued a low-lying area north and west of West Fargo extending to Harwood won’t be necessary once the flood diversion project is completed.
What are called “passive features” built into the diversion channel will accept floodwaters from several western tributaries that feed the Red River — the Rush, Maple and Sheyenne — and prevent the area’s chronic overland flooding problem.
These features will work whenever needed, not just in extreme flood years when officials put the diversion's floodgates into action to hold back water south of Fargo.
The Rush River will empty into the 30-mile diversion channel. The diversion channel will have its inlet south of Fargo near Horace and bypass the west metro area before emptying into the Red north of Argusville, across from Georgetown, Minnesota.
Excess flows carried by aqueducts for the Maple and Sheyenne will be released through spillways into the diversion channel.
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Combined, those “passive features” will prevent notable flooding regardless of whether the three gated control structures that will regulate the flow of flood water into the diversion channel’s inlet are operating, said Joel Paulsen, executive director of the Fargo-Moorhead Diversion Authority.
“Those are the only active elements of the project,” he said, referring to the control gates, which will be used once the Red River rises to 37 feet. Engineers estimate the diversion will operate an average of once every 20 years.
“We consider everything on the channel to be passive structures,” he said.
Because so much of the discussion about the diversion has focused on protecting Fargo-Moorhead, the broader protection the project will provide is often overlooked, said Jason Benson, the Cass County engineer.
“This isn’t just about Fargo or the urban area, it also protects a major portion of the rural residents,” he said.
The major concern from this spring’s flood was overland flooding, including spillover from the western tributaries that feed the Red — the tributaries that will drain into the diversion channel.
“If the diversion were built today it would have protected all those folks in the northwest area going to Harwood,” Paulsen said.
The Rush, Maple and Sheyenne have repeatedly flooded an area about 3 miles wide and 10 miles long extending north and west of West Fargo to Harwood, Benson said.
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The diversion project also will help the existing Sheyenne Diversion, which protects Horace and West Fargo from flooding, to drain. The Sheyenne Diversion is considered a “perched system,” meaning it is on higher ground than land to the west, and therefore can’t drain into the Sheyenne River until the water level drops, Paulsen said.
“Basically all the water coming from the west from the tributaries and overland will be handled by the diversion,” he said. “When the diversion is in place it will accept all that water and everything in the protected area will have little or no impacts.”
Construction of the $3.2 billion diversion project is well underway, including the three gated control structures and the channel. Officials have said the project is on schedule, with completion slated in time to protect against flooding beginning in the spring of 2027.
Officials have said the project will protect about 235,000 people from flooding in the greater Fargo-Moorhead area, which has a total population of 258,000, according to the latest census estimates.
During talks to revise the diversion project’s design in order to win approval from Minnesota officials, Benson was adamant that the revised project include the passive features in the channel design that protect housing subdivisions in large areas of rural Cass County, Paulsen said.
Benson agreed with Paulsen that the diversion will protect the area west of Harwood. “That’s in the protected area,” he said. “It also protects a significant portion of the county’s rural population,” including three townships with a combined population of about 1,500.
During major floods, sandbags still will be needed in the Kindred area, and emergency measures still will be required from time to time in the Davenport, Argusville and Gardner areas, Benson said.
During those floods, Benson estimated that 15,000 to 20,000 sandbags would be required — a small enough quantity that county employees probably would be able to handle, he said.
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By comparison, as a precaution Cass County prepared 100,000 sandbags for the flood this spring, with more than 1,500 volunteers pitching in.
“We won’t need 100,000 once the Fargo-Moorhead diversion’s in,” Benson said. County officials are in the early stages of devising a plan that would keep a steady supply of 10,000 to 15,000 sandbags in storage.
“We’ll always want to have some sandbags available,” he said.
The area around 76th Avenue South remains vulnerable to flooding. There are discussions about a potential Red River bridge at that location that, if built, would be protected to a river level of 37 feet, with two feet of freeboard.
“That’s a complex area,” Benson said.
North of Fargo, the area north of the airport is protected now to a river level in the 40-foot range, he said. During the record 2009 flood, which crested at 40.84 feet, few homeowners had to sandbag in that area, he said.
Also, Benson said, many of the most flood-prone outlying areas have been abandoned and no longer require protection. Since the 1997 flood, Cass County has bought 191 houses vulnerable to flooding, he said.
Once the diversion project is completed, the flood fight in Cass County will resemble the Clay County flood fight, which has to defend just a few vulnerable areas, with township road flooding being the major headache, with a handful of areas requiring sandbag protection, Benson said.
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“That’s more of what our flood fight will turn into once the diverson’s in,” he said.
If the weather cooperates between now and the spring of 2027, the era of major sandbag operations could be over.
“If things work out, this could be the last time we have to do a major sandbagging operation,” Benson said.
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