Chesapeake Bay 1985-2023 Trends and Percent Change in Flow-Normalized Loads

These maps display the long-term trends and percent change in flow-normalized loads for nutrients and sediment across the Chesapeake Bay Watershed from 1985 to 2023. 

Loads are defined as the mass of nutrient or sediment passing a monitored location per unit time. Flow-normalized loads are used to determine trends in water quality over time. 

What is a flow-normalized load?

Loads are related to streamflow, so years with more precipitation and therefore higher streamflow tend to have higher loads. To understand how water quality is changing due to human actions and not due to variability in weather, loads need to be flow-normalized to factor out the influence of streamflow. 

Learn more about Chesapeake Bay Water-Quality Loads and Trends and the USGS Nontidal Network.