by Jamee Larson
The Red River Valley has become accustomed to conversations regarding the Red River and its propensity for flooding. It was only three years ago that the area experienced the second highest flood on record as the river swelled to 40.8 feet; a level over twice that of its eighteen foot flood stage. Many people can remember watching in horror as Grand Forks, ND was devastated by flooding in 1997, and each spring carries the fear that the river could provide Fargo-Moorhead with a similar fate. Because of this reality, the communities of Fargo, ND and Moorhead, MN, along with Cass County, ND, Clay County, MN, the Cass County Joint Water Resources District, and the Buffalo River Watershed District have joined forces with the United States Army Corps of Engineers to develop a proactive approach to the annual flooding in the F-M area. After a three-year study, it is their recommendation that “a diversion channel with upstream storage is required to provide the F-M area with protection from large events and not cause downstream impact.”
What is the Fargo-Moorhead Diversion Project?
In July of 2011, the Corps of Engineers released the 585 page “F-M Metro Feasibility Report and Environmental Impact Statement.” Among their findings was the conclusion that “a diversion channel with upstream storage is the safest and most robust flood risk reduction option available because no matter the size of the flood, a diversion channel with storage will provide some benefits.” According to the report, the Diversion Project would offer permanent protection up to a 100-year flood level, which is defined as any flood with a 1 percent chance of occurring each year, and give the F-M area a fighting chance to protect itself from a 500-year flood, a flood with .02 percent chance of occurrence.
The Army Corps of Engineers believes, “If no flood diversion project is completed in the region, businesses may leave the F-M area, be reluctant to expand, or refuse to locate in the area due to concerns over potential flood damages. Additionally, individuals will be reluctant to remain or move to the F-M area, further dampening economic growth in the region.”
It is estimated that during large flood events, people in the F-M area build as many as eighty miles of emergency levees throughout the city. In 2009, this levee system was constructed in less than two weeks and included the placement of 3 million sandbags. Although these emergency levees have been successful in the past, there is an increased risk of a catastrophic failure, which would result in significant damages and loss of life. The Diversion Authority’s Program Management Consultant Team also believes that “constructing emergency levees also takes a big toll on people – financially, physically, and mentally,” which is why a permanent solution is so important.
What are the Basics of the Plan?
The cost of the Diversion Project is estimated at $1.78 billion. The Federal share makes up about 45%, or approximately $802 million. Local sources would pay 55%, or roughly $90 million. The Corps of Engineers estimates that annual damages due to floods, however, are $194.8 million. Damages from an extreme-level 500-year flood could exceed $10 billion. As flooding continues to become increasingly severe and frequent in the Red River Valley, it is more conceivable that the region could experience this type of extreme-level flood.
The Army Corps of Engineers has recommended a diversion plan known as the Locally Preferred Plan (LPP), which would be built on the North Dakota side of the Red River. The primary features of the plan include:
– Red River control structure
– Connecting channel (Red River to Wild Rice River)
– Wild Rice River control structure
– Diversion inlet weir (at Cass County Road 17)
– Storage Area 1 (levees and flowage area)
– Upstream staging area (with non-structural mitigation)
– Main diversion channel
According to their report, the diversion alignment would start approximately four miles south of the confluence of the Red and Wild Rice Rivers and extend west and north around the cities of Horace, Fargo, West Fargo, and Harwood. It would re-enter the Red River north of the confluence of the Red and Sheyenne Rivers near Georgetown, MN. Along the thirty-six mile path, it would cross the Wild Rice, Sheyenne, Maple, Lower Rush, and Rush Rivers and incorporate the existing Horace to West Fargo Sheyenne River diversion channel.
Two hydraulic structures would control the flows passing into the protected area during larger flood events – one on the Red River and the other on the Wild Rice River, with effect flow widths of 150 feet and 60 feet respectively.
At the Sheyenne and Maple Rivers, aqueduct structures would allow base flows to follow the natural river channels to maintain habitat in the natural channels. Flows in excess of a fifty-percent chance event would be diverted into the diversion channel. The Lower Rush and Rush Rivers would have drop structures that would drop the entire flow of those rivers in the channel. The diversion channel would also have a tieback levee that connects the Red River control structure to the high ground approximately 2.5 miles to the east and prevent floodwater from flowing over land to the north and east of the protected area.
Overall, the Diversion Project would take approximately eight year to complete and will include nineteen highway bridges and four railroad bridges. The affected acreage is approximately 8,054 acres.
In order to eliminate downstream impacts, upstage staging and storing of approximately 200,000 acre-feet immediately upstream of the diversion channel inlet would be required. Storage Area 1 is a 4,360 acre area on the north side of the diversion channel between the Wild Rice River and Sheyenne River and will be formed by nearly twelve miles of embankments and provide 50,000 acre-feet of storage.
What are the drawbacks?
The Diversion Authority acknowledges, “Any permanent solution to provide flood protection for the majority of families and businesses in our community will have adverse impacts on some.” The LPP would remove approximately 6,878 acres of prime and unique farmland from operation. It would also require a substantial number of relocations for communities within the staging area, specifically the communities of Oxbow, Hickson, and Bakke. “We are committed to minimizing these impacts,” said the Consultant Team, “and pledge to treat those who are affected – including those who must be relocated – fairly, respectfully, and with just compensation.”
More information on the F-M Diversion Project can be found at www.fmdiversion.com.
In next week’s F-M Extra:
What is meant by “staging and storage?”
Who will be impacted by the diversion?
What are the alternatives?