This data set reports the event-based chemistry of precipitation water that was collected at the Marcell Experimental Forest (MEF) in Itasca County, Minnesota. The data come from sites in two research catchments instrumented for hydrologic monitoring - the meteorological station located in an upland clearing in the S2 research catchment and the S1 bog as part of the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment. Sample collection and analyses started during June of 2008 at the S2 site and is ongoing. Sample collection and analyses started during December of 2013 at the SPRUCE S1 sites and will continue for the duration of the experiment. The MEF is operated and maintained by the USDA Forest Service, Northern Research Station. The SPRUCE experiment is a multi-year cooperative project among scientists of the Oak Ridge National Laboratory operated by UT-Battelle, LLC and the USDA Forest Service, Northern Research Station. The SPRUCE experiment is funded by the US Department of Energy, Biological and Environmental Research Program.