A groundbreaking study co-authored by Yale researchers has quantified the significant effects of a recent U.S. Supreme Court decision on the nation’s water quality. Published in Science, the research reveals the crucial role of ephemeral streams—streams that flow briefly after precipitation events—in transporting pollutants, sediments, and nutrients from land to major water bodies.

Led by incoming YIBS Donnelly postdoctoral fellow Craig Brinkerhoff and co-authored by YIBS faculty affiliate Peter Raymond, along with Matthew Kotchen from Yale School of the Environment, and Doug Kysar from Yale Law School, the study models contributions of ephemeral streams to over 20 million U.S. waterways. The findings indicate that these streams account for more than 50% of the water in major rivers like the Mississippi and Columbia and over 90% in the Rio Grande. On average, ephemeral streams make up 59% of the drainage network by length.

The study follows the Supreme Court’s 2023 decision in Sackett v. EPA, which excluded ephemeral streams from federal protection under the Clean Water Act. The researchers argue this change could leave over half of the annual discharge from U.S. drainage networks unprotected, underscoring the need for revised legislation and enhanced state and local regulations.

For more information, click here to read the full article on Yale School of the Environment News or here for the full study on Science.