Sample Sites & Collection Water samples will be collected at up to 22 sites in Northern Michigan. Sampling sites will include Burt and Mullett Lakes, with sites in each lake, main inlet and outlet. Burt Lake’s main inlets are the Crooked River, Sturgeon River, and Maple River and its main outlet is the Indian River. Mullett Lake’s main inlets are the Indian River, Pigeon River, and Mullett Creek, and its main outlet is the Cheboygan River. Sites were selected based on proximity to potential PFAS sources. Water sample collection will occur mid-May 2019. Samples will be collected in new 250 mL polypropylene bottles (Shoemaker et al. 2009; Lam et al. 2014; Pan et al. 2017; Moeller et al. 2010). The samples will be collected up to a meter below the surface (Pan et al. 2017; Moeller et al. 2010). Fish samples will be collected from licensed fishermen who catch fish in the Burt Lake and Mullett Lake watersheds in the spring and early summer of 2019. Fish samples will be collected from boat launches in the Burt Lake and Mullett Lake watersheds. Liver samples will be stored frozen in high-density polyethylene bottles, until lab analysis. White-tailed deer liver samples will be collected from deer check stations, with the Michigan Department of Natural Resource’s approval, in November of 2019. Check stations near the Burt Lake and Mullett Lake watersheds are in Onaway and Gaylord, MI. Hunters can volunteer their deer to be part of the study, at which point, the liver sample will be removed from the deer and placed in high-density polyethylene bottles. Samples will be stored frozen, until lab analysis. Physiological Assay Rainbow Trout will be purchased from Harietta Hills Trout Farm. During the experiments, the trout will be housed in artificial streams at the UMBS Stream Research Facility with 5 fish per stream. The fish will be exposed to a 1:1 mixture of PFOS and PFOA totaling, 0 ppm (control), 0.7 ppm, 7 ppm, and 70 ppm for 7 days. Immediately after the exposure, a swimming performance test will occur for each fish separately in a flume with an adjustable flow rate. After a 1-hour acclimation period, the flow rate will be increased slowly until the fish can no longer stay in place. This flow rate will be recorded as the fish’s critical swimming speed. After testing, the fish will be dissected to remove its liver, which will be stored frozen. Lab Analysis Deer and fish samples will be analyzed at Vista Analytical Lab. Water samples will be analyzed at the UMBS Analytical Chemistry Lab. All samples will be analyzed for PFAS on a LC-MS/MS method based on EPA M. 537 v1.1 (Shoemaker et al. 2009). Tissues will also be analyzed with an ELISA test for cytochrome P450 1A1 (CYP1A1) activity, an enzyme that metabolizes toxins. Data analysis Additionally, t-tests will determine the relationship between PFAS levels in all sample types and maximum recommended PFAS levels. ANOVAs will determine the difference between sample sites to investigate which inlets contribute the most PFAS to each lake. Spatial relationships will also be determined by using a spatial autocorrelation.