This dataset accompanies a paper published in Canadian Journal of Fisheries and Aquatic Sciences titled "Effects of spruce budworm defoliation on in-stream algal production and carbon use by food webs". This study examined whether forest defoliation by spruce budworm changed the algal productivity and autochthonous (in-stream) energy supporting macroinvertebrate and fish consumers (using δ13C, δ15N) in twelve streams in Gaspé Peninsula, Québec, Canada, that ranged in watershed defoliation. All sampling for this work was done in summer and fall of 2019 and 2020. This dataset includes landscape data for each stream, sample information for biotic and abiotic samples collected from these streams, stable carbon and nitrogen isotope data for the biological samples, results from the mixing models, water chemistry data, and measures of algal production.