This dataset includes water chemistry data for the La Salle River near Elie, Manitoba, Canada (Water Survey of Canada Hydrometric Station 05OG008) for the time period of 2009 – 2015. The data was collected for hydrological and water quality modelling as part of Agriculture and Agri-food Canada’s Red-Assiniboine Project. Chemical parameters include total dissolved nitrogen, total nitrogen, total dissolved phosphorus, total phosphorus, and total suspended solids. The frequency of data collected ranges from multiple samples per week during high discharge periods from 2013 to 2015 to weekly or sub-monthly frequency from 2009 to 2012 and during periods of low stream discharge.