Illustrating Nutrient Inputs in the Chesapeake Bay Watershed Over Time
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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 and phosphorous 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 watershed with critical nutrient sources from 1985 – 2018. To visually show local managers and planners nutrient inputs, county-level factsheets were designed for nitrogen and phosphorus using the nutrient inventory which will be made available for all counties in the watershed. Graphics on the factsheet include atmospheric deposition, primary nutrient inputs, and agricultural efficiency. Trends over time for the nutrient inputs were analyzed based on a MenKendal Test, and key trends are described on the factsheet. Initial trends from the factsheets identified areas of significant decreases in inputs such as municipal wastewater and nitrate while some areas showed significant increases in urban fertilizer. The inventory and factsheets will serve as a communication tool to illustrate how specific county’s nutrient inputs have changed over time. They will also help local mangers and planners identify the specific sources they need to control to improve local water quality, resulting in better-informed management decisions.