The U.S. has invested $140 per person per year – or more than $1.9 trillion – since 1960 to decrease pollution in rivers, lakes and other surface waters. According to a pair of new studies, this investment in clean water is working, but questions remain about whether the benefits outweigh the costs.

In the first comprehensive look at water pollution in several decades, published in the Quarterly Journal of Economics, researchers from the University of California, Berkeley, and Iowa State University collected 50 million water quality measurements at 240,000 monitoring sites throughout the U.S. between 1962 and 2001. Most of the 25 water pollution measures they used showed improvement, including an increase in dissolved oxygen concentrations and a decrease in fecal coliform bacteria. The number of rivers safe for fishing increased by 12 percent.

To explore these findings further, the researchers teamed up with Catherine Kling, professor of environmental, energy and resource economics in Cornell’s Dyson School of Applied Economics and Management and faculty director at the Atkinson Center for a Sustainable Future, to look at the economics of clean water. The resulting study, published online Oct. 8 in Proceedings of the National Academy of Sciences, painted a murkier picture: Almost all of the 20 evaluations of water pollution policies they examined estimated the costs of the Clean Water Act to outweigh its benefits.

“There is a general belief that benefits of clean water exceed the costs, so we were surprised to find most actual cost-benefit analyses say the opposite,” said Kling. That finding led her team to another critical question: Do the costs of current U.S. water-quality regulations exceed their benefits, or do existing analyses underestimate benefits or overestimate costs?

In other words: Can we trust the conclusion that the benefits of many water quality regulations are less than the costs? Or are water regulations generating benefits no one has calculated yet?

The 1972 Clean Water Act has led to major environmental benefits, from stopping deadly water-related diseases to sustaining commercial fishing and recreation. And according to a 2017 Gallup poll, Americans’ worries about water pollution are at their highest levels since 2001.

But benefits connected to public health are notoriously hard to measure, and existing cost-benefit analyses exclude some important categories of benefits altogether, Kling said. 

Negative health effects of surface water pollution from drinking water, for example, are not considered in most cost-benefit analyses. Likewise, health risks to humans from contact with polluted waters and risk of illness and death for animals who drink toxic bacteria are typically omitted. A final category often left out is the value people place on maintaining and providing clean water for future generations.

“It’s difficult to put a dollar amount on things like the value of clean water or a healthy ecosystem,” Kling said.

But this uncertainty is not inevitable. Targeted research into health effects that can be directly linked to water pollution, along with willingness to pay to preserve clean water for the future and the effects of water pollution on habitat, wildlife and biodiversity in coastal areas, could provide a fuller picture of the true economic benefits of controlling pollution, according to the study authors.

“New research that more accurately incorporates all benefits and costs could provide important guidance on water quality programs and regulatory decisions, particularly at a time when some water quality regulations are facing increased scrutiny and rollbacks,” Kling said.

“There is no question that people value drinkable and swimmable waters,” she added. “Getting better at quantifying the services these waters provide is essential for identifying where and how to focus clean water work.”

Kate Frazer is a freelance journalist for the Atkinson Center for a Sustainable Future.