Flood trends are troublesome for Fargo-Moorhead

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This computer simulation shows a 42-foot level for the Red River. Dark blue areas are river flooding. Orange shows the areas protected by levees. Light blue shows sections that would be affected by back up of flood water through the storm sewer system.

Image courtesy RRBDIN.org

The earliest flood record in Fargo-Moorhead lasted for 100 years until a new mark was established in 1997. Then the flood in 2009 set a brand new high water record.

Just four years later, National Weather Service forecasters say that mark could be broken.

The trend in recent history is toward ever larger floods. If that trend continues, at some point there will be a Red River flood that Fargo-Moorhead cannot defend against.

The numbers tell this story best.

In 1989, the Red River reached 35.4 feet. That flood fight demanded a major effort. Homes were flooded, but the communities were mostly spared. A new bar was set: cities needed to protect from flood waters up to 36 feet.

Fast forward to 1997. The Red River crested at 39.7 feet in Fargo-Moorhead. After an intense, at times desperate effort, the communities kept the water at bay, but only by inches. There was significant damage to private and public property.

Also that year, the Red River inundated Grand Forks, East Grand Forks and Breckenridge, causing billions of dollars in damage. As a result of the catastrophic flooding, Grand Forks and East Grand Forks received federal aid for a massive new levee system and funds were approved for a diversion channel around Breckenridge.

After the 1997 flood, mitigation efforts gained momentum up and down the Red River valley. Fargo and Moorhead bought people’s homes and homeowners who stayed near the river began to build permanent levees to replace backyard sandbag dikes. That year set the bar even higher. Protecting Fargo-Moorhead to a 36-foot river level was no longer enough.

In 2009, the record Red River flood level set in 1997 fell as the river reach 40.8 feet. Once again a massive emergency response protected Fargo and Moorhead, but with only inches to spare.

After 2009, flood mitigation efforts kicked into high gear. Since then, Moorhead has purchased more than 200 homes, and Fargo more than 100. New permanent earthen levees were constructed to 44 feet, a significant safety margin over the record flood level of 40.8 feet.

homedemo3.952.jpgThe city of Fargo is demolishing eight flood-prone homes this week in the Oakcreek neighborhood in preparation for what could be a record flood this spring. (MPR Photo/Nathaniel Minor)

This year, the National Weather Service gives the river a 10-percent chance of reaching 42 feet. It’s still too early to know how accurate that statistical prediction will be, but the trend does not bode well for Fargo-Moorhead.

Each time flood waters have set a new record, the cities have responded by building levees higher. The problem with that scenario is that the levees can’t go any higher.

For a levee to work, it must connect on each end with higher ground. But Fargo and Moorhead are built on what was once the flat bottom of a glacial lake. Beyond a 44-foot elevation, engineers get nervous, there’s not much high ground to be found.

Because of that, a U.S. Army Corp of Engineers study found levees inadequate for permanent flood protection. The Corp of Engineers has recommended a $1.8 billion diversion channel. The diversion hasn’t been authorized or funded by Congress. IF that happens, construction will take a decade.

If floods continue to trend higher, it’s only a matter of time before the Red River throws a punch for which there is no defense.

That’s why officials in Fargo and Moorhead are pushing so hard for permanent flood protection, and hoping they get that protection in time.

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