Visitors flock to the Sierra Nevada national parks including Yosemite (YOSE) and Sequoia and Kings Canyon (SEKI) to immerse themselves in the natural beauty and recreational opportunities offered by the region's water features. However, the water quality that enhances these experiences is vulnerable to contamination from per- and polyfluoroalkyl substances (PFAS). These chemicals pose a significant threat to the ecological health and safety of the park's waterways. Ensuring the purity of these waters is essential to preserving the natural resources and recreational value that draw so many people to visit the Sierra Nevada.

Due to the increased risk of PFAS to aquatic ecosystems, this project will investigate PFAS pollution in rivers and riverine food webs of YOSE and SEKI. This project will address the possible extent, duration, sources, and ecological impacts of PFAS in remote and pristine waters of the Sierra Nevada.

To measure PFAS levels in river water, we will employ “polar organic chemical integrative samplers” (POCIS), which are placed in the rivers for 30-day periods, where they absorb PFAS from the water onto a filter membrane. POCIS are standard methods used in PFAS monitoring to provide time-integrated assessments of these pollutants. Additionally, we will analyze PFAS accumulation in dragonfly larvae and multiple trout species, serving as bioindicators of ecological health and trophic transfer. This approach will offer critical insights into the environmental presence and biological impacts of PFAS, contributing to a broader understanding of their ecological footprint in these iconic national parks.