At the Snohomish River estuary, seafloor sediment composition correlates with river discharge. With an increase in river discharge mixing of sediments occurs and the heavy metal particles become suspended in the water column. With a decrease in river discharge sediment concentrations deposit on the sea floor. Ocean Research College Academy (ORCA) students, including ourselves, collected the data used in this investigation on monthly research cruises throughout 2015. We hypothesized that in 2015, higher levels of Snohomish River discharge would lead to lower concentrations of heavy metals in the sediment. River discharge data from the Snohomish River was collected three days prior to the date of sediment collection. Arsenic, copper, and lead concentrations were sampled from three sites in Possession Sound: Mount Baker Terminal (MBT), a buoy southwest of the jetty, and the delta. The results showed that heavy metal concentration decreased with increasing river discharge, with the exception of one site. At MBT, south of the Snohomish River, all of the heavy metal concentrations declined with the increase of river discharge. A rise in river discharge of 1,980 to 25,400ft^3/sec caused a decrease in arsenic from 4.84 to 2.49mg/kg, copper from 15.2 to 8.53, and lead from 7.17 to 2.81mg/kg. The site at the river delta followed the same trend, with a range in river discharge of 1,980 to 10,400ft^3/sec correlating with a decrease in arsenic from 9.34 to 6.06mg/kg, copper from 20.5 to 13.4mg/kg, and lead from 5.94 to 3.04mg/kg. The exception was Buoy, located to the southwest of the jetty. With an increase in river discharge from 3,910 to 29,300ft^3/sec, arsenic rose from 5.74 to 7.14mg/kg, copper from 15.4 to 21.5mg/kg, and lead from 4.31 to 5.78mg/kg. Heavy metal concentrations have been found to be harmful to marine organisms in high concentrations. Thus for further research we will be collecting data on heavy metal concentrations found in local plankton populations, in order to find a correlation between the two.