This dataset contains streamwater chemistry and stormflow data that were collected to assess short- to mid-term wildfire impacts on streamwater quality in the seasonal Pacific Coastal Temperate Rainforest. Field campaigns occurred between April - May 2022 and October 2022 - January 2023 and targeted nine historic wildfire areas (fires occurring 2015 - 2022) that span a range of sizes and burn severities. Synoptic grab sampling at baseflow was undertaken at 37 streams (19 burn-affected, 18 reference) to enable paired comparisons; stormflow samples were collected using passive rack samplers that collect water on the rising limb at four sites and automatic ISCO pump samplers at the most recent (2022) fire site. Flows tended to be low because of an ongoing severe drought throughout fall 2022. The dataset includes measured concentrations of dissolved organic carbon (DOC), nutrients (total and dissolved phosphorus and nitrogen, soluble reactive phosphorus, nitrite + nitrate, and ammonium), major cations (calcium, potassium, magnesium, sodium, aluminum) and anions (sulfate, chloride). There are also in situ measurements collected with a YSI multiparameter probe (temperature, pH, dissolved oxygen, specific conductance) and dissolved organic matter (DOM) optical properties (absorbance and fluorescence spectra) measured on a Horiba Aqualog. Derived DOM indices (SUVA254, spectral slopes), parallel factor analysis (PARAFAC) component scores, and fluorescence indices (BIX, HIX) are provided. Catchment characteristics derived from geospatial data are also supplied to contextualize the water quality data, including catchment size, slope, aspect, elevation, burn severity, vegetation type and coverage and soil type. Given the expectation that wildfire prevalence and severity will increase in this traditionally wet region, it is likely that the impacts observed in this study will become both enhanced and more widespread in the future.

This research is funded by NSERC Discovery, NSERC Canada Graduate Research Scholarship – Master's (CGS-M) and Alberta Graduate Excellence Scholarship (AGES).More Information on GIS-extracted parameters can be found under "Further details".