The city of Louisville, Kentucky, sits low in a valley along the Ohio River. When it rains heavily, water can quickly rise, overflowing the stormwater drains and submerging parts of downtown, low-income neighborhoods near the river, and the local college campus.
Louisville is nowhere close to the coastal areas in Florida and Texas that have received the lion’s share of attention for the effects of climate change. But it’s at increasing risk for sewer system overflows and more frequent flooding, thanks to a perfect storm of aging stormwater systems and climate change.
“We are racing against the clock,” said Eric Friedlander, Louisville’s chief resilience officer, told The Daily Beast. “When you talk about massive infrastructure we are putting in place, and the construction time schedule, it feels to me there is still time—but we’re up against it.”
Louisville residents are reminded of flooding threats with signs that mark how high water reached during the Great Flood of 1937, when nearly three-quarters of the city was underwater. Inevitably, an event like that will happen again. An Army Corps of Engineers study found that warmer temperatures and changing weather patterns will lead to more frequent storm surges from the Ohio River, consequently increasing flooding in low-lying areas like Louisville (PDF).
Other inland communities, from Baton Rouge, Louisiana to rural West Virginia, have also seen a surge in flooding. The most recent National Climate Assessment suggests heavy downpours are more frequent and inland floods cause more damage than any other severe weather event. Another study showed that thunderstorms in the Southeast could dump 80 percent more rain in some areas, causing flooding to be four times worse by the end of the century, said Andreas Prein, a climate scientist at the National Center for Atmospheric Research.
“It is one of the most severe consequences of climate change inland in the U.S.,” Prein said.
The stress of increased water flow is wreaking havoc on the nation’s stormwater systems, which are reaching the end of their lifetimes (PDF). Unable to handle the intensity of heavy rainfall and storm surge, water backs up and causes flooding, “There’s so much more water to get rid of in a city,” Prein said. “It needs a sophisticated drainage system, which we don’t have.”
Flooding is not just a nuisance—it’s also a public health and safety issue. Combined sewer systems in hundreds of communities, from Memphis to Oklahoma, backup during heavy rains, allowing millions of gallons of untreated sewage and stormwater runoff to flow into streets and waterways.
Old wastewater treatment plants are flooding more frequently too, releasing contaminated water into rivers and bays. Heavy rains in Tampa this summer caused 329,000 gallons of sewage to spill in a river.
Chronic flooding takes an economic toll too, said Maria Koetter, director of Louisville’s Office of Sustainability, adding that it can cause businesses to lose money and affect tourism. “This is the real deal,” she said. “We have to put up the money to make sure these systems don’t fail.”
But no one wants to pay for it. Louisville’s Metropolitan Sewer District says it needs $4.3 billion over the next two decades to upgrade the city’s collapsing brick pipes, many installed after the Civil War. Some cities are trying to finance upgrades with increased property taxes or sewer fees.
“A lot of these projects are very big, and taking that on is costly,” said Laura Lightbody, project director for Pew Charitable Trust’s flood-prepared communities program. “Some of these projects are put on hold while the city tries to grapple with and piece together the financing.”
And stormwater management is only part of the solution. To be climate resilient, Lightbody said, cities should take a holistic approach, requiring green infrastructure, preventing development in floodplains, redirecting or elevating roads, and building levees or flood walls.
In addition to its major stormwater project, Koetter said Louisville requires water catchment like rain gardens for construction projects and is doubling its tree canopy to absorb water and keep the city cooler. In Nashville, buildings must be four feet above base flood elevation, and the city has been buying out homes in floodplains for decades to prevent development where it consistently floods. Brevard, North Carolina, requires a “no adverse impact” certification so development does not catalyze erosion.
Most initiatives happen at the local level, but the federal government needs to provide guidance to incentivize cities, Lightbody said. Under the Trump administration, however, that’s becoming more difficult: 10 days before Hurricane Harvey hit in August, the president repealed an Obama-era rule that mandated infrastructure projects like roads and bridges be designed to survive rising sea levels and storm surge.
Cities face dire consequences if they don’t improve these systems, but it’s a massive, long-term undertaking.
“It’s almost like we’re reverse engineering our cities,” Lightbody said. “We built them up and poured a lot of concrete, and now we’re trying to figure out how to bring green space because we’ve seen the economic and flood benefits of it.”