Chesapeake Bay Watershed County-Wide Nutrient Inventory: Assessing Spatial Patterns and Trends to Inform Management Decisions

Abstract:

Understanding inputs to local watersheds is the first step for managers and planners to implement targeted restoration practices. The Chesapeake Bay Program Phase 6 Watershed Model provides the nitrogen (N) and phosphorous (P) input data for counties within the Chesapeake Bay Watershed. There are currently national nutrient inventories to identify nutrient inputs but having this information at a county level is potentially useful to local managers. Inputs to the Phase 6 model was utilized to create a detailed nutrient inventory for all the counties in the Bay watershed from 1985 – 2018. Using the nutrient inventory, trends for each individual source were estimated using the Mann-Kendall Test, which were converted into county-level, watershed-wide 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. Local and state managers should be equipped with the best, up-to-date local-level information available on the likely sources of pollution and how these sources have changed through time. By using the Chesapeake Bay Watershed inventory to tailor their near- and long-term management strategies, they can derive key metrics that identify inefficiencies or success in the use or handling of N and P. The inventory, in conjunction with the trend maps, can help identify location-oriented problems by showing the distribution of a nutrient input over space, over time, and in relation to other inputs. To make all this information more accessible to county managers, a web application for the data and graphics is being considered for development which allows users to look at the counties and sources pertinent to them. These products provide the connection between the data and potential courses of action ultimately leading to better informed management decisions within the watershed.