This post is part of a series about climate change and the increasing risk of floods releasing toxic chemicals from industrial facilities.
As Hurricane Harvey lingered over Texas in 2017, it created a wall of water that swallowed much of Houston. Catastrophic flooding over a wide swath of southern Texas left towns, cities, and the countryside under feet of water. The floodwaters sloshed toxic chemicals from the area's 10 oil and gas refineries, 500 chemical plants, and 12 Superfund sites around "like a wet mop," according to one resident who lives near the ExxonMobil refinery and chemical plant. The torrential rainwaters engulfed her home, and she was forced to swim with her four young children through a toxic soup that smelled like "a rotten sewer." Their exposure to contaminated floodwaters likely accounted for the skin and strep throat infections her children later developed. Rice University researchers also collected floodwater samples just a single block from her home and found levels of benzo[a]pyrene, a known carcinogen, above an acceptable EPA threshold for human cancer risk.
With climate change and increasingly frequent extreme weather events, we are at risk for more Houston-like "toxic soup" flooding events. We have tried to tame our rivers to keep ourselves dry while allowing industry to build in floodplains and closing our eyes to the risks of toxic releases during floods. Over time, we have seen parallel but uncoordinated efforts on flood control, emergency management, and industrial chemical regulation, often in response to some large flood event and/or industrial spill.
Over the last two centuries, officials at the local, state, and federal levels have struggled to balance their roles in flood control and regulation of toxins with budgetary constraints and their willingness (or reluctance) to confront industry interests in the service of flood control and environmental protection. Many state and local governments, in the desire to expand their economic base and boost employment, have promoted reckless economic growth by opening floodplains to industrial development. The toxic chemicals and hazardous waste many of these industries introduce into our waterways often pose dangers to our health that are both obvious and hidden.
While biological toxic flooding (from sewage and other organic waste) has occurred for centuries, the growth of the synthetic chemical industry increases the risk and amount of toxic substances that end up in our waterways during a flood. Indeed, routine toxic dumping produced dramatic visuals in the past (including the repeated Cuyahoga River fires of the 1950s and 1960s, which eventually helped galvanize determination to pass the Clean Water Act). However, the sources of danger that can lead to toxic flooding today are more often hidden in storage containers and underground pipelines.
Preventing toxic floodwaters requires coordination of both flood management and protection against toxic releases. As straightforward as that sounds, in practice it has been anything but simple. The federal government was initially cautious to play a role in flood control, viewing it as a state issue. Only in 1917, after significant repeated floods along major waterways that crossed state lines, did the federal government make its first flood control appropriations, continuing a post-Civil War strategy exclusively focused on levees. This levee-only strategy created a false sense of safety, boosting construction in floodplains and exacerbating flooding (such as the 1927 Great Mississippi Flood) rather than preventing or reducing it. The economic boom after World War II included an expansion of synthetic chemical industries, increased state and local government competition for heavy and light industry, and led to more industrialization in floodplains, putting chemical toxins in the potential path of floodwaters.
Meanwhile, the federal government shifted its focus from "flood control" to "flood risk reduction and mitigation," culminating in federally subsidized national flood insurance and disaster relief mechanisms in the 1960s. These strategies sought to create disincentives to residential and industrial construction in floodplains by encouraging local government floodplain management regulations. But in practice, because the various players had different and competing interests, the strategies had the opposite effect, resulting in increased construction in precarious areas, often inhibiting nature's own systems for effectively "absorbing" excess waters. Houston's expansion is a case in point. It ignored the necessary role of floodplains in managing floodwaters, exposing people and property to danger of the sort wrought by Harvey.
During the 1970s, the toxic effects of air and water pollution were more visible and raised concerns among both citizens and policymakers, finally leading to a series of critical federal laws (the Clean Air Act, the Clean Water Act, the Safe Drinking Water Act, the Toxic Substances Control Act, Superfund, and more) to regulate specific toxins and toxic releases. Yet despite continued toxic flooding events at Superfund sites, oil and gas pipelines, and other industrial sites, neither Congress nor the executive branch have successfully undertaken any concrete, coordinated response to reduce the risk of toxic floodwaters. Indeed, politicians have allowed the Superfund program to go badly underfunded (to the benefit of polluting industry, exclusively), which has slowed the pace of cleanup and increased the likelihood that floodwaters will spread toxic waste.
Modern History: How Houston Became a Toxic Soup during Hurricane Harvey
Houston's post-Harvey experience illustrates the consequences of unlearned lessons from more than a century of flooding, industrial development in vulnerable areas, and climate change. NPR's "Three Reasons Houston was a 'Sitting Duck' for Harvey Flooding" tells the story of how Houston's city planners allowed unchecked urban and industrial growth without adequate zoning regulations. And they were not alone in promoting growth: Many state and local officials also created a friendly environment for industry, demonstrated by the large number of chemical plants and oil refineries in the area.
However, nearby neighborhoods and surrounding communities had little or inaccurate knowledge of flood risks or of the toxic chemicals in their surroundings. Furthermore, the federal government and other authorities have provided limited public notification about the extent of toxic flooding and related human health risks even months after Harvey struck the Texas coast. In the alternative, investigative journalists are now informing the public of these risks: The Houston Chronicle and the Associated Press recently catalogued more than 100 Harvey-related toxic releases, of which authorities alerted the public in only two cases.
Houston is not the only example of toxic flooding – or of heavy residential and industrial development in floodplains where recent flooding has taken place. St. Louis has allowed significant residential and commercial development in land that was underwater in the Great 1993 flood. In 1994, heavy rains in southern Texas caused major soil erosion in floodplains and San Jacinto river channels, causing eight oil and gas pipelines to rupture. Gasoline from one spill ignited, shooting flames along the river, causing fires and explosions in homes and vehicles along the riverbanks, and injuring more than 500 people. Even before climate change began to make intense storms more dangerous and more frequent, we could not stop severe storms from striking. We still can't. But at the very least we can avoid putting chemicals in their footprint.
1994 San Jacinto River Fire (photo credit: U.S. Geological Survey)
The history of toxic flooding shows that we have lessons to learn, related both to our coastlines and inland regions. The comparatively recent effort to regulate industrial pollution has largely failed to adequately address the need to integrate flood response, just as earlier efforts to prevent flooding, and then to disincentivize development in floodplains, failed. As Harvey and other flood-induced toxic releases demonstrate, the confluence of limited regulation, poor compliance with reporting requirements, and lack of coordinated response by regulatory agencies has created a situation in which communities are not being fully informed about releases and industry remains mostly unregulated when it comes to the risks of toxic flooding. These risks will only grow with the extreme weather brought on by climate change. We need to learn from the mistakes of the past, continue advocating for solutions, and press for a coordinated approach to reducing the risks of toxic flooding events.