Surface coal-mining practices in Appalachia involve removal of topsoil and rock layers to access coal seams, which exposes minerals to weathering and releases ions into nearby headwater streams. These elevated ion concentrations increase specific conductance (SC) and alter aquatic microbial and macroinvertebrate communities by influencing growth, changing food resource quality, and decreasing overall diversity. We aim to assess the influence of freshwater salinization on aquatic macroinvertebrate resources, focusing on seasonal variations in isotopic composition and abundance of algae and coarse and fine organic matter (CBOM, FBOM). We hypothesize that long-term elevated salinity will affect carbon and nitrogen cycling due to microbial stress, thus altering nutrient assimilation and transfer. We measured the quality and quantity of OM in nine streams in VA and WV across a mining-induced SC gradient of < 100 μS/cm to >1,000 μS/cm. From October 2023 to February 2025, we collected algae, CBOM ( >1mm), and FBOM (<1 mm) in fall, winter, spring, and summer. Preliminary data from October 2023 to August 2024 indicate that FBOM dominates spatially and temporally, regardless of mining activity. However, isotopic signatures did differ among OM sources. Algae from October 2023 showed a peak in both carbon (-20.32 δ13C‰) and nitrogen (5.05 δ¹⁵N‰) at SC ~1,500μS/cm, followed by a drop to -27.59 δ13C‰ and -2.36 δ¹⁵N ‰ at SC ~1,863μS/cm, suggesting salt subsidies algal growth at intermediate salinity levels. The % carbon in OM was similar across sites in October 2023, whereas % nitrogen declined slightly from reference to elevated-SC sites. We will integrate % nutrient and enriched/depleted isotopic ratios for resources across February - August 2024 with these preliminary results to test seasonal and other drivers of resource availability among sites. By investigating basal resource patterns, we can track changes in trophic function and exchange in disturbed headwater streams.