WATER QUALITY INDEX AND CONDUCTIVITY TO STUDY THE LATERAL MIXING DOWNSTREAM OF THE NORTH AND WEST BRANCHES OF THE SUSQUEHANNA RIVER

The North and West branches of the Susquehanna River converge at Sunbury, Pennsylvania to create a Lateral Mixing Zone (LMZ) that extends all the way downstream from Selinsgrove, after which islands help to facilitate mixing. In this study, the movement of the LMZ was observed in accordance with multiple precipitation events over a four month span from June to September of 2015 in addition to other data acquired from prior years. The goal of this study is to identify if the water from the two branches is present at all times between site 1 and 2 to eventually place two permanent monitoring stations in the same area. YSI 556 Multimeter and a boat were used to continuously take data samples across the river between sites 1, 2, 3, and 4. Site 1 is located on the West Branch of the Susquehanna River while Sites 2 and 3 are located on opposite sides of Byer Island, while Site 4 is on the East bank (Figure 1). A GPS was used to track movement and help identify the location of the LMZ along with the data associated with each data point along all transect. Data was collected before and after various periods of precipitation and discharge rates. Four Hydrolab sondes were also deployed twice at each site in June and again in September, to support the identification of the water of the two branches. Among all the measured parameters including water chemistry, physical properties, from both the YSI multimeter and the sondes have demonstrated that specific conductivity produced the clearest trends of LMZ between the two branches. During the study period, the values of specific conductivity has increases, but the trend identifying the type of water sources was still noticeable. The analyses of all data determined that as the discharge increases, the LMZ moves away from the West branch and towards the North branch up until a threshold point and then slightly shifts back to the West branch. In addition, a Water Quality Index (WQI) was performed for the two branches based on eleven different parameters similar to that discussed in Vicente (2009).