Published January 14 2012
Diversion Discussion: Leaders, critics debate protection
For metro-area government leaders, the target is 500-year flood protection, a goal engineering studies showed could be best provided through a Red River diversion.
But critics argue that Fargo-Moorhead officials seek unnecessarily too much protection when a lesser option would suffice with fewer consequences to rural communities.
Several area residents wrote the U.S. Army Corps of Engineers last summer, asking why they’re pursuing such a massive and expensive project when cheaper alternatives could protect to what the residents considered adequate levels.
The answer lies not with the corps, but with Fargo-Moorhead metro leaders who had the final say on the decision.
While corps engineers conducted the research, modeling and analysis for the three-year feasibility study, a board of metro leaders directed the corps on which actions to take when narrowing the alternatives.
Those same officials then decided on the chosen plan for permanent protection: a 35-mile-long, half-mile-wide Red River diversion channel that’s undergoing design this year.
At a meeting of the Metro Flood Study Work Group in November 2009, local leaders unanimously set the bar high: They wanted protection against a 500-year flood event, and any project that offered less wouldn’t do.
That decision didn’t come without research or debate, said Fargo City Commissioner Tim Mahoney and Clay County Commissioner Kevin Campbell, co-chairmen of the now-dissolved working group.
Grand Forks’ system of floodwalls and levees and Winnipeg’s diversion channel provided a basis for comparison on what types of protection are already in use in the Red River Valley, Mahoney said.
Grand Forks’ project protects against a 250-year flood event, while Winnipeg’s protects against a 700-year event.
But in order to achieve that, Winnipeg officials shelled out $665 million in 2005 to expand their 40-year-old diversion channel and double its capacity.
“We don’t want to do this twice; we only want to do it once,” Mahoney said. “We always want to be a little overprotected.”
“We thought if you’re going to go to this expense and you’re going to have a diversion, you might as well have it be cost-effective,” he said.
Corps engineers’ analysis showed that with 100-year flood protection, metro leaders would still find themselves coordinating flood fights too often, Mahoney said.
The historic flood of 2009 also played a key role in the decision, he added.
On March 28, 2009, the Red River at Fargo surged to 40.84 feet, the highest level on record.
Before that, the previous record set in 1997 was believed to be the 100-year flood event of our lifetime. The 2009 flood surpassed that by more than a foot.
The realization that still-larger floods weren’t out of the realm of possibility set off more hydrology and hydraulics studies of the Red River’s temperaments.
In spring 2010, the corps’ results came back, and they offered no comfort.
The corps changed the definition of a 100-year flood event to a level that would measure 42.4 feet on the Fargo gauge, about 4 feet higher than the previous definition.
Under the new standard, 2009 was a 50-year event, and a 500-year flood would reach a level of 46.7 feet, corps officials said.
Fargo and Moorhead are in the process of shoring up emergency levees to protect against a 42.5-foot flood, but the Red River diversion would allow greater protection for a broader area of the metro, officials said.
But critics say if we’ve never seen even a 100-year flood under the revised standard, then why do we need 500-year protection?
The threat of losing a flood fight is enough reason to set the bar high, Mahoney said in response.
“Look at Minot: They lost, and they won’t recover from that,” he said. “Grand Forks took 10 years to recover and just get back to the baseline.”
If Fargo-Moorhead lost the fight against a 500-year flood without the diversion in place, the metro area could face more than $6 billion in damages, corps research shows.
“The corps has come out and said that we could see a 46.7-foot flood,” Campbell said. “If we could see that, then we’d be falling short with 100-year protection.”
He added, “A 500-year flood doesn’t mean that it happens only once every 500 years. It just means that there’s a 0.2 percent chance that it can happen in any given year.”
Local and federal officials acknowledge there’s no guarantee a 500-year flood will happen anytime soon, but they say it’s better to be prepared and build a diversion now that could handle it.
“We have more water than we ever thought we’d have coming,” Mahoney said. “It may not come in our lifetime; it may come in somebody else’s lifetime, but people will be happy to have the diversion.”
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