Pollutant Concentration vs. Pollutant Load
Concentration = Amount of Pollutant. Measurements involve taking water samples to a lab for chemical analysis, though some parameters can be measured directly in the stream using ion-specific electrodes. When measuring agricultural runoff, the data may not accurately assess the impacts of a single agricultural producer if no boundaries exist between neighboring production fields or if the farms practices lead to variability in runoff volume, throughout the day or week.
Load = The mass or weight of a pollutant which passes cross-section of a river during a specific amount of time. TMDL (total maximum daily load) assesses the maximum pollutant load a waterbody can accept before becoming impaired. It also helps catalog the implementation of management measures designed to improve water quality. The higher the volume of flow, the lower the total concentration of pollutants.
Minnesota’s “watershed pollutant load monitoring network” (WPLMN) is a long-term program that measures pollutant load information from the state’s rivers and streams and tracks water