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Raise Iowa Gateway to 500-year levels, continue open meetings

BY DI EDITORIAL BOARD | JULY 19, 2011 7:20 AM

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Across eastern Iowa, the damage from the 2008 flood is still visible, and the memories are still fresh.

Iowa City and Johnson County officials are working both to rebuild and to prepare for future flooding. An open forum last week gave citizens a chance to weigh in on the efforts to raise the Park Road bridge and Dubuque Street between Park Road and B'jaysville Lane. When making this decision, the city should continue to solicit and consider the input of residents, and we should ensure that a desire for frugality doesn't sacrifice the efficacy of solutions.

Besides the direct consequences to transportation of the bridge and street location, their effects on the flow of floodwater have consequences miles away.

The bridge is a crucial choke-point for the river when it floods. During the 2008 flood, logs and debris stuck under the bridge caused the floodwaters to rise upstream. According to the Iowa City Gateway project website, the backwater at the Park Road bridge caused upstream neighborhoods to experience 8 to 11 more inches of flooding.

Raising the street and the bridge will do more than simply prevent inconvenience. When they are both covered with water, emergency access to I-80 is severely curtailed. Emergency-vehicle operations can't be suspended in the event of a flood; instead, they frequently increase.

Reducing the backwater at the Park Road bridge is one of the main goals of the plan, and Gateway Project special manager Melissa Clow told the DI last week that raising the bridge and widening its beams would alleviate this problem.

The current phase of planning determines the level the bridge and Dubuque Street are to be raised. Several different proposals are being considered, of varying efficiency and cost. The city is considering whether to raise the bridge to the level commensurate with a "100-year flood" or a "500-year flood." Once the level is determined, the type of bridge structure will be considered.

Although it is more expensive, the city should raise the bridge and Dubuque Street to the levels of a 500-year flood. Gambling people's lives and property on a desire to avoid spending would be irresponsible; the Gateway Project should be done right the first time so that future devastation on the scale of the 2008 flood is avoided.

In the last decade, flood-measurement technology has failed predict the extent of flooding. Flood-prediction models run simulations based on local weather variables that are in constant flux, and the modeling technology will continue to have difficulty making predictions due to global climate change. With predicted increased rainfall, it's likely that 500-year floods — a flood that has a 0.2 percent chance of happening each year — could occur. As 2008 showed, one massive flood can have huge and lasting consequences.

Another controversial issue relates to the proposed levee by Taft Speedway, which may also have complicated effects downstream. Concerned citizens should educate themselves on all of the issues involved in flood mitigation and address their thoughts to city officials; the Taft Speedway project is controversial, and it has resulted in allegations of poor communication. It's important for residents to remain involved with the planning process.

It's extremely important for every citizen's voice to be heard on flood recovery and flood-damage mitigation. The science of flooding is such that changes on any part of the river can affect areas far up or downstream, and minor construction projects can affect the entire community. The continued town-hall meetings and open forums on the subject are laudable, and the planning for the Gateway Project needs to continue to proceed out in the open.

Finally, the city should raise the Park Road bridge and Dubuque Street to 500-year flood levels. It may be more expensive, but the past decade's floods have shown that the city can't afford to bank on probabilities.


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