Nitrogen Critical Loads and Estimated Exceedances in NPS Areas (2015–2017)

Critical loads are a tool the NPS uses to assess and understand the impacts of nitrogen deposition to park ecosystems and help inform policy and management decisions to protect them. This analysis compares critical loads to the maximum level of nitrogen deposition (from the 2015–2017 average NADP Total Deposition model) present within a boundary. When the total deposition exceeds the critical load there is an increased risk of ecological harm. These critical loads (adapted from Pardo et. al 2011) are developed at the ecoregion scale and should only be used to evaluate risk. Where park specific or more recent critical loads exist, these should be used instead.