Scientists are ringing alarm bells about a significant new threat to U.S. water quality: as winters warm due to climate change, they are unleashing large amounts of nutrient pollution into lakes, rivers, and streams.

The first-of-its-kind national study finds that previously frozen winter nutrient pollution—unlocked by rising winter temperatures and rainfall—is putting water quality at risk in 40% of the contiguous U.S., including over 40 states.

Nutrient runoff into rivers and lakes—from phosphorus and nitrogen in fertilizers, manure, animal feed, and more—has affected water quality for decades. However, most research on nutrient runoff in snowy climates has focused on the growing season. Historically, cold temperatures and a continuous snowpack froze nutrients like nitrogen and phosphorous in place until the watershed thawed in the spring, when plants could help absorb excess nutrients.

Read the full article about winter nutrient pollution at Environmental News Network.