The Potomac River earned the unwelcome distinction of seizing the Number 1 spot on the American Rivers list of the Most Endangered Rivers of 2026 (overview; full report).
What many experts have deemed the largest sewage spill in U.S. history—the January failure of the Potomac Interceptor pipeline—played an outsized role in propelling the Potomac to the top of the list. But American Rivers also saw significant threats in "an unprecedented surge in data center development, particularly in northern Virginia and portions of Maryland."
Regarding the dangers of bacterial contamination, the group's report emphasized that the Potomac Interceptor is more than 60 years old, and "many of the region's wastewater pipes … are approaching or have passed their 50-year service life. "Congress must reauthorize critical water infrastructure funding bills," the group said.