Land managers are reintroducing North American beaver (Castor canadensis) into Western U.S. waterways to restore degraded riparian ecosystems. Beavers create cascades of sequential dams that alter river corridor geomorphology and redox chemistry. These changes can produce conditions conducive to the production of methylmercury (MeHg), a bioaccumulating neurotoxin. Increasing atmospheric mercury (Hg) deposition in the western U.S., combined with beaver expansion, has the potential to dramatically change aquatic biogeochemical cycling and ecological processes, particularly rates of methylmercury (MeHg) production. In this study, we investigated the degree to which beaver activity expands anoxic conditions, influences the interaction of sulfur (S) and Hg cycles, and increases rates of Hg methylation in montane ecosystems. We present results from water and sediment samples from Coal Creek (Crested Butte, CO) and Trout Creek (Colorado Springs, CO). We quantified total Hg and MeHg concentrations in water and sediment, and sediment methylation rates. Preliminary results indicate that periodically inundated sediment within a beaver meadow had on average, higher MeHg concentrations (2.15 +- 3.32 ng g-1) than the stream sediment (0.93 +- 1.51 ng g-1, p < 0.05). Additionally, MeHg concentrations in pond surface water (0.322 +- 0.041 ng L-1) and the beaver pond outlet (0.11 +- 0.41 ng L-1) were elevated compared to the inlet (0.05 ng L-1). Although not significant (p > 0.05), the results suggest that beaver ponds may be associated with higher production of MeHg, which can be transported downstream. Overall, this study expands our understanding of MeHg production in high-elevation beaver meadows and provides insights for mountain communities and land managers regarding the consequences of continued beaver expansion for water quality.