Data Description: The majority of this dataset is water chemistry grab sample data collected post-Cameron Peak Fire in the Cache la Poudre Watershed between the years of 2021 and 2023. This dataset also includes historical data collected pre Cameron Peak Fire by the Rhoades lab at the US Forest Service Rocky Mountain Research Station. These data are focused on basic water quality parameters, as well as cations and anions. Data were collected at various reservoirs in the Cache la Poudre watershed as well as the mainstem of the Cache la Poudre River. This project is ongoing and additional data will be released as it is analyzed. Background Information: The 2020 Cameron Peak wildfire (CPF) was the largest wildfire in Colorado history at over 200,000 acres. The CPF burned a large proportion of the Cache la Poudre watershed, in particular areas surrounding high elevation reservoirs. This work is funded to support ongoing source water protection programs by the City of Fort Collins, Greeley, Thornton and Northern Water. In collaboration with the Rocky Mountain Research Station (USFS, RMRS), we are sampling various reservoir, tributary, and mainstem sites of the Cache la Poudre watershed. This field campaign allows us to analyze trends in water quality focusing on nutrients and other key constituents mobilized post-fire. The goal of this project is to understand how these nutrients affect algal growth in reservoirs and how those changes are propagated downstream. The reservoirs studied are the following: Barnes Meadow Reservoir, Chambers Lake, Comanche Reservoir, Hourglass Reservoir, Joe Wright Reservoir, Long Draw Reservoir, and Peterson Lake. Historical data (prior to 2021) was collected by the Rhoades Lab at the USFS' Rocky Mountain Research Station. File Descriptions: The primary data file is data/cleaned/CPF_reservoir_chemistry_up_to_071023.csv. Column definitions and units are defined in the file metadata/Units_Cam_Peak.xlsx. Methods used to collect these data are outline below or in metadata/rmrs_procedures.png Location metadata file is data/metadata/cpf_sites.csv. A basic map showing all sampling locations is available at cpf_sites_map.html. Code is housed in the scripts folder and contains the following files: 00_colors_and_groups.R provides groupings and colors for plots created in future analysis. 01_chem_prep.qmd adds metadata to most recent .csv of water chemistry data supplied by RMRS lab. distance_finder.R uses NHDflowlines to calculate distances from furthest downstream site, PBD. cpf_sites_map.R uses location metadata to create cpf_sites_map.html Data are housed in the data folder and it contains the following: cleaned: This folder contains the most recently available dataset and has associated burn severity and location data added to the chemistry data. The addition of the metadata was accomplished using the 01_chem_prep.qmd R script. raw: These data were directly received by the ROSSyndicate from RMRS lab managers. Downstream users are encouraged to use the collated data file CPF_reservoir_chemistry_up_to_071023.csv in the cleaned directory. metadata: this contains location data, parameter/column name definitions, units, and methods used at the RMRS Lab. The README file in this folder explains burn severity classifications used in the files sbs_watershed.csv,sbs_watershed.csv and cpf_sites.csv Sample Collection: Samples were collected and processed using the Rocky Mountain Research Station's Biogeochemistry Lab, overseen by Timothy Fegel and Charles Rhoades, according to the methods described in rmrs_procedures.png Version: v2023.09.01

Funding: This project was funded by the City of Fort Collins Utilities, City of Greeley Utilities, City of Thornton Utilities and Northern Water.