Symbolize your Streams layer to show line direction (Symbology>Format Line Symbol). The direction of Streams lines is important as each line represents the from- and to- directions in the line theme, which should match the sampling saved in the Salmon_Table. Remove all joins from the Streams layer. Select the stream section not flowing north and run the Flip Line tool so all Stream section go upstream. Clear selection. 

Which stream section was not flowing north (upstream)? specify the Streams_ID.