Heidi Shaffer, Published July 31 2011
Diversion Discussion: Dredging Red River ineffective flood-fighting measure
Forum readers can ask their diversion questions and get answers straight from the U.S. Army Corps of Engineers in this bi-weekly column.
Kenny LeNoue of Fargo asks:
If a deeper channel in Bismarck helped with the flooding, and the Mississippi River is deepened for barge traffic, why do we not dredge the Red River and make it deeper to hold more water?
U.S. Army Corps of Engineers’ response:
Digging the Red River channel deeper and wider to allow for more flow to pass through the Fargo-Moorhead metropolitan area was considered, as well as increasing movement in Oakport Coulee.
These alternatives were eliminated for several reasons, including environmental impacts and cost-effectiveness. If implemented on a hydraulically effective scale, it would be highly detrimental to the river and riparian ecosystems and would likely not be permittable.
Dredging and widening the channel would have very limited hydraulic effectiveness, meaning limited ability to move or store water in the quantities necessary, and would likely negatively affect the stability of the riverbanks. Operations and maintenance costs would be high and long term.
Environmental mitigation costs would be extreme, assuming the alternative is even possible.
The cities would still face large residual risks because of the option’s ineffectiveness, and if continued dredging was not maintained, any benefits of the project would be lost.
Moorhead City Council member Diane Wray Williams asks on behalf of constituents: Protecting land south of Fargo for future development is a violation of Executive Order 11988. How can the project go all the way to Hickson, N.D., protecting undeveloped land, and be within the guidelines of 11988?
The proposed plan removes additional land from the floodplain compared to the Minnesota alignment, but then the corps used Executive Order 11988 as an excuse not to consider the southern and western alignments. The federal rule states that the project cannot impact downstream communities, but also stipulates that the alignment cannot be moved farther south to save upstream communities.
Why does it apply in some instances and not in others?
Corps’ response: Executive Order 11988 prohibits support of floodplain development if there is a practicable alternative. If no practicable alternative exists, then impacts to the floodplain must be minimized.
The results of this study have shown that a diversion channel is the alternative that best meets the project purpose, “to reduce flood risk, flood damages and flood protection costs related to the flooding in the Fargo-Moorhead Metropolitan Area.”
There is not a practicable alternative located outside the floodplain and, as such, the rule requires that impacts to the floodplain be minimized. The diversion alignment of the locally preferred plan removes some land from the floodplain and leaves other areas in the floodplain.
Various channel alignments were considered, and the alignment of the proposed diversion channel was selected to address flooding from five tributaries while also minimizing costs and the overall impacts to the floodplain and environment.
Do you have a question about the proposed Fargo-Moorhead diversion? Send us your question, and we’ll ask the U.S. Army Corps of Engineers.
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