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A Map To Solving Local Flooding

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Louisiana Office of Community Development
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The Louisiana Watershed Initiative committee worked on this map for nearly a year, taking it on tour across the state and soliciting input from local officials. The final map was approved in August.

As rainfall increases and storms intensify, local officials across Louisiana are looking for ways to protect their citizens. They’re putting up levees and floodwalls and trying to manage all of the water. But floodwater doesn’t follow parish lines, so state officials are working on a solution.

As Hurricane Barry headed for the coast in July, Sharonda Kotton and her family were on edge. They live near Bayou Manchac in Iberville Parish, a densely-wooded rural area just south of Baton Rouge. It floods often.

Kotton says she was scared, “Because you never know, I could have woken up and water would be in the house… you have no control over Mother Nature.”

But then, Iberville Parish president Mitch Ourso decided to take matters into his own hands. He got a bunch of workers to start putting up a temporary “AquaDam” along the road to protect the neighborhood.

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Credit Johnny Manela
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Bayou Manchac resident Johnny Manela took this photo of what he says is the AquaDam installed by Iberville Parish officials ahead of Hurricane Barry. They were later asked to take them down after a lawsuit was filed by East Baton Rouge Parish.

Kotton watched from her house in the woods. “There were big trucks, in and out, working...it made me feel safe.”

Except the people on the other side of those barriers did not feel safe. They feared that by setting up a wall on one side of the bayou water would get pushed back onto neighborhoods on the other side, in East Baton Rouge Parish. Officials there ended up suing Iberville parish president Ourso and serving him a federal restraining order. He was forced to take down the dams. Neither party agreed to an interview, given pending litigation.

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Credit Louisiana Office of Community Development
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Watersheds extend beyond state boundaries, as seen on this U.S. Geological Survey map. The Watershed Initiative is working with representatives from Arkansas, Mississippi and Texas to coordinate water management.

This is just one example of a conflict playing out across the country. As climate change brings heavier rains and more flooding, local leaders are desperate to protect their people. But this patchwork approach can have unintended consequences.

Now, officials with the state have built a map and a computer model that they hope will start addressing problems like these.

The map is built around watershed boundaries and has eight different regions. It was created by the Louisiana Watershed Initiative, which includes officials from the Department of Transportation and Development, the Governor’s Office of Homeland Security and Emergency Preparedness, the Department of Wildlife and Fisheries, the Office of Community Development and the Coastal Protection and Restoration Authority.

The map is based on rivers and natural drainage, not political jurisdictions.

Over the years, officials have built roads through drainage basins, or levees in floodplains.

Resilience Planning Manager with the Office of Community Development, Alex Carter, says projects like those may alleviate flooding in one community, but officials need to ask, “what does it do downriver?” She says, “The water has got to go somewhere.”

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Credit Tegan Wendland / WWNO-New Orleans Public Radio
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WWNO-New Orleans Public Radio
Alex Carter is a Resilience Planning Manager with the Office of Community Development. She is part of a team that spent about a year drafting a new map of watersheds in Louisiana.

Watershed Initiative modellers are using federal data, local maps and even flying planes over the state using LIDAR to make this new map.

The state just received $1.2 billion from the United States Department of Housing and Urban Development for flood mitigation projects, such as retention ponds and dams, but parishes will need to work collaboratively within their watersheds to apply for the money.

Laura Lightbody works on flooding issues as a policy expert with Pew Charitable Trusts. She says the federal government is starting to take note, investing in adaptation and mitigation, rather than just cleaning up after disasters. Research has shown that every dollar invested in disaster mitigation by federal agencies saves society $6.

Lightbody says other states are exploring watershed models like Louisiana’s. “South Carolina, Virginia, Washington, Tennessee - are all trying to put these plans in place right now.” She adds “...if Louisiana can figure it out, there's some real lessons to be had here.”

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Credit Michigan Sea Grant / https://www.michiganseagrant.org/lessons/
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https://www.michiganseagrant.org/lessons/

The state is trying to use a map to undo hundreds of years of working against nature. State officials need local officials to see the benefits. So as part of the process, they took the map on a tour and met with hundreds of parish leaders, asking for their input.

Carter says they were met with some resistance. But once they explained it, people started realizing that surviving together, in the face of climate change, was more important than arbitrary parish boundaries.

Support for the Coastal Desk comes from the Greater New Orleans Foundation, the Walton Family Foundation, and local listeners.

Tegan has reported on the coast for WWNO since 2015. In this role she has covered a wide range of issues and subjects related to coastal land loss, coastal restoration, and the culture and economy of Louisiana’s coastal zone, with a focus on solutions and the human dimensions of climate change. Her reporting has been aired nationally on Planet Money, Reveal, All Things Considered, Morning Edition, Marketplace, BBC, CBC and other outlets. She’s a recipient of the Pulitzer Connected Coastlines grant, CUNY Resilience Fellowship, Metcalf Fellowship, and countless national and regional awards.

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