Water-quality patterns and trends in the Chesapeake Bay and its watershed: Integrated monitoring and modeling approaches to advance science and inform management
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The Chesapeake Bay Watershed consists of over 150 counties with different geographic features, land uses, and connections to the Bay which leads to various inputs of nutrients on the landscape. Analyzing the spatial patterns of individual nutrient sources in all the counties across the watershed can highlight areas with restoration progress or areas facing challenges which can potentially be useful to local managers to understand drivers of water quality and for understanding the overall relationship among nutrients in the watershed. The Chesapeake Bay Program Phase 6 Watershed Model provides the estimated nitrogen and phosphorus input data for the counties within the Chesapeake Bay Watershed and was utilized to create a detailed nutrient inventory for all the counties in the watershed with critical nutrient sources from 1985 – 2018. Using the nutrient inventory, trends for each individual source was found for all the counties based on a MenKendal Test and developed into county-wide Bay watershed maps. Additional maps were made to visually represent the individual nutrient input for the year 1985 and one for 2018 along with a map for the long-term median. Comparing these maps can show the distribution of a nutrient input over space, over time, and in relation to other inputs which can help explain the spatial patterns. The patterns from this analysis will identify location-oriented problems and be used to improve planning and lead to better water quality management decisions. The views presented here are those of the authors and do not represent official views or policy of the U.S. Environmental Protection Agency.