Soil and surface water nitrogen and caffeine data from 2019, and 2019-2020 trail counts of hikers in Loch Vale Watershed, Rocky Mountain National Park

Daily visitor use in Rocky Mountain National Park has increased substantially since 2014, raising questions about the impact of human waste on water quality in popular areas without latrines. Human urine contributes nitrogen, and the ecological and biogeochemical effects of nitrogen from atmospheric deposition have long been the topic of study in Loch Vale watershed, Rocky Mountain National Park. Nitrogen from atmospheric deposition has been found previously to lead to lake eutrophication and altered algal species assemblages. Our data were collected to evaluate the impacts of visitors to a popular alpine watershed in Rocky Mountain National Park. There are three separate data files: soil sample locations and concentrations of nitrate, ammonium, and caffeine (used as a marker of human waste) for May-September 2019; surface water sample locations and concentrations of nitrate, ammonium, and caffeine (used as a marker of human waste) for May-September 2019; and trail count data for June-September 2019 and 2020. The study was conducted by USGS and Rocky Mountain National Park researchers and yielded results regarding the nitrogen input (which was calculated as 2% of total annual N inputs) and also revealed information on visitor behavior, namely that many visitors do not follow standard Leave No Trace guidelines for locating privy sites 200 feet or more from a water body.