Prepared in cooperation with the International Joint Commission - Dissolved Oxygen Monitoring on the Souris River, 2019–23

In evaluating the WQO, the discrete samples only indicated one instance where DO concentrations were less than 5 mg/L compared 6 to the continuously recorded data where the daily minimum was less than the WQO for a total of 161 days and the daily mean was less than the WQO for 81 days. [...] Also, likely because of algal dynamics in the channel, the highest daily maximum DO concentrations were recorded mostly in the summer months, although the highest concentrations were in the spring 2021 and in the late fall in 2022. [...] Continuous Water Quality in the Souris River 2019–23 The three sites on the Souris River were chosen for additional DO monitoring because they provided the best opportunity to capture potential influences on DO in areas below major flow control structures and because identifying the connection of streamflow to DO at the international border is a focus of the ISRB. [...] The lowest minimum DO concentrations generally were in the summer and winter months, although DO was not measured in most of the winter months near Sherwood because of extreme low streamflow conditions that resulted in a lack of water in channel to support the operation of the sensor. [...] Also, likely because of algal dynamics in the channel, the highest daily maximum DO concentrations were recorded mostly in the summer months, although the highest concentrations were in the spring of 2021 and in the late fall of 2022.