Coal-mining practices in Appalachia expose rocks to accelerated weathering, resulting in the release of minerals and associated ions into nearby streams. This ion runoff increases specific conductance (SC) and can alter microbial and macroinvertebrate communities, impacting such ecological processes as production, respiration, and decomposition. We assessed how a mining-induced salinity gradient affects organic matter decomposition by measuring changes in rates of tensile strength and ash-free dry mass (AFDM) loss, and measured change in microbial and algal activity on the organic matter. We predicted 1) decomposition would follow a subsidy-stress response, where rates increase alongside moderately elevated SC due to an increase in microbial and algal activity from ion subsidy, then decrease after a certain point due to ion stress, 2) woody organic matter decomposition would occur linearly with SC compared to cotton strips due to the carbon being slower to breakdown via hydrolysis, and 3) decomposition would occur at a faster rate in the streams than in the riparia due to an increase in microbial activity and physical abrasion created by streamflow. From October 2023 to February 2026, we deployed and retrieved wood veneers and standardized cotton strip assays seasonally in nine Virginia and West Virginia streams with a mining-induced salinity gradient of ~20 μS/cm - ~1,185 μS/cm. We measured decomposition through tensile strength of cotton strips and AFDM of wood veneers, and measured microbial and algal activity by conducting chlorophyll-a and respiration analysis on wood veneers. Preliminary data show seasonal variation in decomposition on both substrates, with May and August 2025 having the fastest decomposition, and cotton strips decomposing faster in streams than in the riparia. Chlorophyll-a increased on the wood veneers with salinity, while respiration exhibited a subsidy-stress response to salts, with microbial activity decreasing after 400-450 μS/cm. Overall, elevated salinity does seem to have season-specific effects on organic matter decomposition and algal activity, though it doesn’t appear to strictly follow a subsidy-stress response, while the microbial activity does seem to show a subsidy-stress relationship with salinity. These findings contribute to understanding salinity’s impacts on organic matter decomposition and help guide future research into potential environmental remediation.