Headwater streams in the Appalachian Coalfield region have been subject to salinization resulting from mountain-top removal practices and subsequent leaching of mine rock into headwater streams. This increase in salinity, measured as specific conductance (SC), can significantly affect ecosystem function, especially when coupled with other stressors like flow. We are monitoring nine headwater streams: three reference (SC<100 µS/cm), three mid-salinity (SC 200-700 µS/cm), and three high salinity (SC>1,000 µS/cm), for SC, stage, and dissolved oxygen to assess how multiple stressors (salts, flow extremes) change ecosystem processes. Although the hydrologic regimes are similar across all streams, ranges in SC differ substantially, allowing us to assess differences in these interactive stressors via site concentration-discharge relationships. We observed SC dilution with increased flow across all sites but mined sites exhibited greater SC variation and, consequently, higher salinity rate of change with water level: log-transformed slopes were 1.32 for high-salinity streams, 0.69 for mid-salinity streams, and 0.39 for low-salinity streams. Understanding these relationships across a salinity gradient will allow us to test the role of salt and flow stressors on ecosystem metabolism. In high SC streams, we expect gross primary production (GPP) and ecosystem respiration (ER) to follow a subsidy-stress response to increased salinity. In contrast, flow is anticipated to be a primary stressor in reference sites but dilute salts in higher-SC sites at higher flows. After generating site-specific water level-flow rating curves, we will couple SC-flow analyses with model-generated metabolism values to observe how these interactive stressors influence metabolism. GPP and ER will be modeled against each stressor, and this coupled with the C-Q relationships will assist us in evaluating the role each plays in ecosystem metabolism. Understanding these interactions will assist in predicting how freshwater salinization is changing stream function across a range of salt pollution sources, flow regimes, and biomes.