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Long Flood History, but Feds Have a Short List of Solutions

In 2019, University City officials asked the U.S. Army Corps of Engineers for options. Now, officials have a strategy spelled out in the Corps draft plan released in April: Build a detention basin.

Midwest Flooding
In this aerial photo, floodwater from the Mississippi River threatens the maximum security Menard Correctional Center Thursday, Dec. 31, 2015, in Chester, Ill. Surging Midwestern rivers forced hundreds of evacuations, threatened dozens of levees and brought transportation by car, boat or train to a virtual standstill Thursday in the St. Louis area.
(AP Photo/Jeff Roberson)
(TNS) - As water rushed from the River Des Peres into hundreds of University City homes after record-shattering rains late last month, city and federal officials already had a recommendation for how to reduce longstanding flood risks along the waterway.

For decades, experts have studied the flood-prone upper parts of the urban watershed, eyeing ways to protect residents and structures from rising waters. Year after year, heavy rains have fallen and streets and structures have flooded.

In 2019, University City officials asked the U.S. Army Corps of Engineers for options.

Now, officials have a tentative but specific strategy spelled out in the Corps’ draft plan released in April: Build an approximately 8-acre detention basin to store water upstream in Overland’s Woodson Road Park.

But, given the scale of local flood problems and the modest scope of the recommended project — estimated to cost less than $10 million — experts warn that the study’s “tentatively selected” strategy, though helpful, will not go far enough to protect area residents.

How to fix a status quo of flood risk?

Despite being labeled as a once-in-more-than-500-years rain event, some victims with damaged homes saw the late-July disaster as a tragedy waiting to happen.

“This is the worst thing I’ve ever dealt with in my life,” said University City Council member Tim Cusick, whose home was swamped by four feet of water. Piles of ruined belongings sit outside his neighbors’ homes.

“Their losses are just tremendous,” he said.

Damage assessments from recent flash flooding are still in their initial stages. But even without an official overview, University City — which is essentially bisected by the upper River Des Peres — features among, if not atop, the hardest-hit parts of the region from the massive rains that hit July 26 and July 28.

Gregory Rose, the city manager for University City, said at least 300 homes in the municipality are estimated to have been “severely” affected by the flooding.

Rose said the city government, alone, estimates that it has sustained at least $18 million in property damage — including six police cars and damage to places like its fire department and public works facilities.

The July destruction is merely the latest chapter in the troubling history of flash flooding along the river — if one even calls it that. (The Corps’ draft report considers it a “mixed use sewer and storm drainage system” with a natural channel along much of it.)

For example, before the latest flood, other recent ones occurred in 2008, 2011, 2013, 2014, 2019 and 2020, according to the Corps.

A separate 1988 Corps report about the upper river basin lists damaging flooding in 1957, 1970, 1973, 1978, 1979, 1980, 1981, 1982 and 1986.

Research has found that the upper River Des Peres is Missouri’s most sensitive watershed, in terms of rainfall raising stream water levels.

Local flood risks today are made worse by forces like climate change and urban design. That’s because, as fossil fuels warm the atmosphere, the air gains the ability to hold more water, thus increasing the potential for major downpours. Meanwhile, the prevailing layout of the urban landscape is poorly suited to handle bursts of extreme rain, with paved surfaces funneling more water, faster, to nearby streams and drainage systems — setting them up to flood.

Known risks

Up to 1,100 structures and 3,000 people are at risk in the 100-year floodplain, according to the Corps’ calculations. And if no action is taken, repeated bouts of flooding would increase the prevalence of vacant lots and degraded housing in geographically vulnerable areas.

Over the past decade, University City officials have enlisted a task force and a commission to examine flood issues; in 2019 they asked the Corps for an analysis of how to reduce flood risks.

The Corps report examined a host of possible strategies, including modifications to the river channel, diversion projects, use of levees or floodwalls, elevating structures and pursuing the targeted buyouts of homes.

But eventually, the analysis zeroed in on detention basins as an area of particular cost-effectiveness and promise, noting that they buck the trend of other projects that can unintentionally amplify flood risk.

“Floodwalls, levees, and channel modifications that constrict the river are human-made alterations to a natural system,” the report states. “Therefore, they would cause adverse impacts to the hydraulics and hydrology of the River Des Peres by constricting the water and speeding up its flow rate. Detention basins, in contrast, mimic natural floodplain processes, and so would have a beneficial impact.”

The agency examined five possible sites for detention basins, although it determined that three were too far downstream to remove “worthwhile” amounts of floodwater. It also considered some spaces occupied by businesses, including a large parking lot and seafood supply store on Olive Boulevard , and another spot that is home to two commercial buildings next to Woodson Road Park.

Ultimately the Corps shifted its gaze slightly and identified the 7.9-acre site at Woodson as the best place for the proposed project, “because it is currently in use as open space and would therefore have a lower cost.”

The proposed detention basin would cost an estimated $9.9 million. Most of the cost would be covered by federal sources, and University City would be responsible for about $3.5 million.

What are we supposed to do?’

But there are concerns.

The detention basin should help a watershed that’s now starved of water storage, but it’s not enough to resolve flood issues by itself, according to members of University City’s stormwater commission. It’s also smaller than the 10-acre minimum size sought by the Corps — a threshold the agency said was “desirable to retain a substantial volume of water.”

And some critics, like Cusick, say there are bigger flaws and challenges that stem from the Corps’ process of evaluating flood solutions — points he intends to bring up during a University City Council meeting scheduled for Monday.

Much of his frustration is fixated on two key points.

One is that the Corps’ modeling underestimates local flood risk, compared to the levels of flooding residents have seen. In response, the Corps said it has recalibrated its modeling based on “what the actual flood conditions were” in years like 2008, for example.

And Cusick says the Corps discards too many potentially helpful strategies because they’re too expensive.

“I just don’t feel like the Army Corps of Engineers is an advocate for us,” said Cusick, who also serves as the city council's liaison to University City’s Commission on Storm Water Issues. “They’re more concerned about benefit-cost ratios than they are about people’s homes and the people that live there... What are those lives worth?”

Cusick’s frustration isn’t solely with the Corps. A complicated tangle of entities, including the Metropolitan St. Louis Sewer District and the Federal Emergency Management Agency, split aspects of related oversight and management.

“No one wants to take responsibility for the River Des Peres,” he said.

Individual city governments, like University City, could pursue property buyouts on their own, but have limited budgets. Anything that would directly affect the river, though, requires partnership with other entities.

And it would be a tall order to develop a system that could contend with the recent record-busting rainfall. But some wonder whether that should become a collective goal, to retrofit the region’s built environment to handle more volatile weather extremes made more likely by climate change.

“Should we really be looking more at how do we make the River Des Peres a better channel that can accommodate these potentially 500- and 1,000-year floods?” asked Rose, the city manager. “I believe that this is a regional problem that will require a regional solution.”

The Corps expects to complete a final report about its planned course of action in the middle of 2023, and any project is still multiple years — and potentially multiple floods — away from its anticipated completion

In the meantime, plenty of people in the area are still in the early and arduous stages of piecing things together, after having their homes overrun by floodwater.

“Many of our residents are suffering,” said Rose. “We are heart-stricken, because we know some of our residents lost everything.”

He encouraged flood victims to call 211 for help.

©2022 the St. Louis Post-Dispatch.

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