Resource managers and policy makers require information about the risk to forest ecosystems from nitrogen and sulfur deposition which continue to affect the growth and survival of trees in forest ecosystems across the US. In this assessment we compare different ways of aggregating the critical loads (CL) for multiple species in the same plot and include, for the first time, an assessment of the uncertainty associated with the critical loads. Based on a prior analysis of US Forest Service Forest Inventory and Analysis (FIA) data for more than 1.4 million individual trees measured between 2000 and 2016 and US-EPA CMAQ model deposition estimates, we found that the majority of the 94 tree species we evaluated had detrimental responses to N and or S deposition. Here we evaluate how the way the critical loads are aggregated in each plot (using an area-weighted average for the CL or selecting the most protective CL) affects the confidence in the CL across the country. This information is critical for resource managers and policy makers in decision making and represents an important enhancement in critical loads risk assessments.