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A Third of Texas City Is Likely to Flood, but Some Areas Aren’t on FEMA Maps

About 118 square miles of Fort Worth has some flood risk, says a city assessment. FEMA designated about 50 square miles as part of its flood zone, but its review is associated with waterway flooding, not urban flash floods.

by Luke Ranker, Fort Worth Star-Telegram / July 17, 2020
Richard Muller, of Sienna Levy District, walks past 1,600 sand bags that volunteers just made in case the levy breaks on Aug. 30, 2017 in Sienna Plantation neighborhood in Missouri City, Texas. Max Faulkner/Fort Worth Star-Telegram/TNS

(TNS) -- About a third of Fort Worth’s roughly 350 square miles could flood regularly, but some of those at-risk areas do not show up on federal flood maps.

The city is considering developing local flood assessments by the end of the year, if the City Council approves. But Fort Worth’s mayor and a group of real estate professionals worry doing so could hamper development, affect property values and open the door for lawsuits.

Roughly 118 square miles of the city has some kind of flood risk, according to a city assessment. The Federal Emergency Management Agency has designated about 50 square miles as part of its flood zone, which is used by lenders and insurance agencies. But FEMA’s assessment is associated with waterway flooding and not urban flash floods.

The city’s stormwater management department says an additional 68 square miles, including portions of popular neighborhoods like the Near Southside, Linwood and Arlington Heights, are also prone to flooding. That information is not easily available to residents, said Jennifer Dyke, stormwater program manager.

The department wants to make these non-FEMA flood zones public through online maps and notifications to property owners. Developers of properties one acre or smaller would be required to certify that they took into account flooding on their property as well as the development’s impact on neighboring properties. Currently projects on an acre or smaller have no requirement to assess flood risk.

“This is really a flood warning effort,” Dyke said. “We don’t obviously have enough funding to fix all of the problems citywide, so that’s where this mapping comes in, to inform people of those risks.”

The idea is part of an effort to address the city’s $1 billion stormwater management problem, said assistant transportation and public works director Greg Simmons. Fort Worth has more than 300 dangerous flash flooding spots, but even with a voter-approved fee increase, it can afford to fix only 40, about $70 million worth.

Dyke’s team compared reports of flooding to engineering modeling and found where floodwaters may reach outside FEMA flood zones. Two designations were developed beyond the federal risk assessment.

About 65 square miles falls under what the city calls “potential high water areas.” These areas have a risk of flooding, based on previous reports. Just three square miles lie in “city flood risk areas.” Here the stormwater employees drilled down to the parcel level and looked at hydrological models.

The proposal is to require developers to certify projects within the three square miles that are most at risk, Dyke said. The potential high water designation would simply inform residents that a property or street may experience flooding not predicted by FEMA.

Annually in Texas, the amount of flooding that occurs outside FEMA’s flood plain has risen from an average of about 15% in 1986 to an average of 55% in 2014, according to a report from Gov. Greg Abbott’s commission to rebuild Texas following Hurricane Harvey.

In Fort Worth, 76% of flooding between 1980 and 2019 was outside the federal flood plain.

Local flood maps

Fort Worth would not be alone in mapping flooding beyond FEMA’s assessment.

Through its zoning map portal, the city of Dallas shows non-FEMA flood risks. In Denver, “potential inundation areas” can be highlighted on the city’s interactive map. A similar option is available in Raleigh, North Carolina. Suburbs are also advancing non-FEMA flood mapping, including Grand Prairie, which shows localized flooding through the city’s drainage master plan.

In Houston, Texas A&M professor Sam Brody piloted a flood map program similar to Fort Worth’s that focused on the statistical likelihood a property would flood, rather than hydrological engineering. The Center for Texas Beaches and Shores has since developed a parcel-level tool that shows non-FEMA flood risk in Dallas, Galveston, New Orleans and Miami.

The localized maps are increasingly more important as the risk of urban flooding grows, he said. A combination of aging drainage systems, rapid development and increasing rainfall make it more likely cities experience flooding outside the federal flood zone.

These maps cost less and take less resources to update than hydrological models, he said.

“It’s not a replacement of the FEMA maps, but a complement, to better understand the flood hazard and risk at a household level,” Brody said.

Development impacts

But there is some hesitation from the City Council and Realtors.

Price, when the council was briefed on the project last month, said she has had reservations for a long time about the idea of local flood maps.

She said she worried properties would be placed on a local flood map and then not removed if the issue was fixed. Such a designation could hurt property appraisals and insurance rates, she said.

“I still think there’s a lot of work yet to be done on this program,” Price said. “I think we still really need the critical answer to exactly why we are doing this? It won’t address our drowning issues on our roadways or that kind of flooding.”

In 2018, four people died in five months on flooded Fort Worth streets.

The Greater Fort Worth Association of Realtors shares Price’s concerns, said CEO Robert Gleason.

Disclosure forms require sellers to note if a property is in a FEMA flood zone and if it has flooded, but there’s no requirement regarding local flood designations. This could open the door to liability issues if a seller doesn’t note that a property is on the city’s flood map. But disclosing the information, even if the property hasn’t flooded, may make it difficult to sell, he said.

Gleason said he saw merits for city staff to use the non-FEMA flood maps internally while vetting proposed developments, but he wasn’t sure it should be public knowledge.

“On the outside, you may say, ‘well, wouldn’t it be great if we had this mapping out there that shows some of these at-risk flood areas,’ but there’s some pretty major consequences, I think,” he said.

Dyke said the local flood designations would be significantly easier to change than those produced by FEMA, which often take years to update. If a property is mislabeled, city staff can quickly reevaluate and remove it.

Being placed in the city’s flood map likely wouldn’t hamper development in the long run, she said, noting other factors developers consider include the market, economy and location to jobs or schools.

“If the structure actually floods that will have a significant impact on property values, but just mapping itself would probably just have a small impact,” she said.

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