The raster data represent the amount of wet nitrate deposition in kilograms per hectare from 2014 to 2016. Summary data in this indicator were provided by EPA’s Office of Atmospheric Programs. Wet deposition data are from the National Atmospheric Deposition Program/National Trends Network (NADP, 2018) (http://nadp.slh.wisc.edu/). This indicator aggregates data across 3-year periods to avoid influences from short-term fluctuations in meteorological conditions, and wet deposition data were interpolated among monitoring stations to generate the map shown.