Since the passage of the Clean Water Act almost 50 years ago, the U.S. government has investedover $1 trillion to combat water pollution. The costs of the law seem relatively clear, but what about the benefits?

In a recent paper, David A. Keiser and Joseph S. Shapiro, take a deep dive into the benefits of the Clean Water Act. Keiser and Shapiro note that academics and regulators alike have debated whether the Clean Water Act has actually cleaned up the waters of the United States, and whether the benefits of the law have been worth the costs.

Although many U.S. rivers and streams do not meet federal pollution standards, Keiser and Shapiro write that the law has curbed water pollution overall. That said, the law has had relatively low net benefits—especially when compared to the federal Clean Air Act.