Sulfate export in high elevation watersheds is increasing due to thawing ice features and accelerated weathering of sulfide-bearing minerals. Sulfate can be an important control on the microbial production of methylmercury (MeHg) in low oxygen, wetland environments suggesting elevated sulfate export may increase MeHg production within mountain ecosystems. We studied a Colorado Rocky Mountain watershed that has experienced a 300% increase in sulfate export over the past 30 years and has ~10% wetland cover to assess the relationship between elevated sulfate export and MeHg production. We measured MeHg concentrations and production rates in wetland soils and overlying water across different wetland types. Subalpine peatlands have significantly higher concentrations of MeHg and rates of MeHg production compared to other wetland types, as well as the surrounding dry soils. To assess sulfate controls on MeHg production, we amended subalpine peatland soils with sodium sulfate to mimic enhanced export. The 50 µM (2.12±0.81 %MeHg production/day) and 100uM (2.64±0.82 %MeHg production/day) sulfate amendments resulted in significantly higher methylation rates compared to no sulfate additions (0.27±0.25 %MeHg production/day). The 200 µM treatment was also higher on average (1.30±0.78 %MeHg production/day) but not significant. These results suggest subalpine peatlands are sulfate-limited and that continued export of sulfate from high elevations could stimulate increased MeHg production with implications for human and ecosystem health.