Key findings from the study:

• A large share of today’s nutrient loads comes from older, lagged nutrients stored in the landscape, helping explain why water quality often improves slowly. This also highlights how water management decisions made now can shape future water quality.

• Total nitrogen and phosphorus loads increased in many areas nationwide from 2000 to 2020, mainly due to lagged sources, agriculture and changing streamflow.

• The models show when and where nutrient problems are most intense, and what the sources are, which can support management planning for more effective solutions.

You can also learn more and access the study and its accompanying data here: From source to streams: New national models estimate seasonal nutrients over 21 years in rivers across the U.S. | U.S. Geological Survey