Tracking Outcomes and Metrics to Measure Progress
In recent years, the Task Force has worked to set and report on metrics to help better track progress towards the hypoxic zone and nutrient loading reduction goals. This work is key to understanding whether the conservation actions that states and others are taking will help us reach the interim target and goal of a 20% reduction in nitrogen and phosphorus delivered to the Gulf by 2025.
No one tool is perfect for measuring our progress because of the wide variety of factors that influence nutrient loading. Thus the Task Force and its partners are working to measure basin-wide nutrient reductions at multiple scales through multiple tools, including the following:
- A decadal look at conservation through the USDA-supported CEAP and USGS-supported SPARROW efforts;
- State, regional and basin-scale loading models, including CEAP and SPARROW, that examine nutrients in the basin through source analyses;
- Statistical and other trend analyses of nutrient concentrations in the MARB across multiple time-frames using data collected by states, USGS National Water Quality Assessment (NAWQA), EPA National Aquatic Resource Surveys (NARS), watershed groups, researchers, and those who use the Water Quality Portal for Nutrient Water Quality data (WQX) to house nutrient water quality data;
- Biennial reports on point and nonpoint source trend information; and
- The annual NOAA hypoxia zone monitoring cruise, which is a key tool of the Task Force to measure progress.
In November 2017, a few Task Force affiliates presented on how the Task Force is working to track progress as part of "The Current" webinar series of the North Central Region Water Network. Watch the webinar here: Conservation Practice Tracking for the Mississippi River Basin.
The Task Force has explored tools that can be used to further document progress. In 2020, the Task Force developed a compendium of tools to track conservation highlighting known technologies to track agricultural conservation in the United States.
The Task Force Trends Workgroup is considering new metrics to complement current metrics for evaluating water quality trends in the basin. A focus is presenting flow-normalized nutrient loading trends via the Weighted Regressions on Time, Discharge, and Season (WRTDS) methodology. Total nitrogen loads to the Gulf from the Mississippi River are shown below from 1979 and 2019. Results from the two metrics used by the Task Force to evaluate progress towards nutrient reduction targets—the five-year moving average loads and the flow-normalized loads—are shown.