Seattle’s Combined Sewer Overflow (CSO) system discharges approximately 100 million gallons of untreated sewage and storm water runoff into its waterways annually. The sewer system includes two combined waste streams: waste from sewer basins, which captures storm water runoff, and wastewater from buildings and industry. Pollutants in the effluent such as human waste, automotive by-products, pesticides, and pharmaceuticals can degrade ecosystems. To determine the impact that CSO outfalls have on Seattle’s waterways, this study tested for pollutant levels in sediment near two discharge areas: Elliott Bay and the western end of Seattle’s Ship Canal. Sediment samples were collected using a Van Veen grab, then handled and stored using sterile, inert materials to avoid contamination. Sediments were tested for heavy metals including mercury, via cold-vapor atomic absorption, and lead, via inductively coupled plasma mass spectrometry. The organic pollutants ammonia, nitrate, and phosphate were quantified via automated calorimetry. Laboratory testing for pollutants was done in accordance with EPA guidelines or standard analytical methods. Results were compared to the Washington Department of Ecology’s Sediment Management Standards. Preliminary results suggest that lead and mercury levels do not exceed the Department of Ecology’s sediment quality standards, while cadmium levels are slightly above or below recommended levels at each site. This data can be used as a baseline to help better understand the contribution of CSOs to pollution levels in these areas. More research will be necessary to determine the extent of damage to ecosystems near the outfalls.

Possession Sound is located within Puget Sound of western Washington. Students at the Ocean Research College Academy (ORCA), a dual enrollment program in conjunction with Everett Community College, have collected environmental data in Possession Sound such as pH, and dissolved oxygen (DO) concentrations since 2004. Our group participated in this academic year, 2015-2016. Based on seasonal trends, it was hypothesized that pH of Possession Sound would be higher during summer, due to usage of CO₂ for photosynthesis, and lower during winter due to lack of photosynthesis. ORCA students collected water chemistry data at the sample site, Mount Baker Terminal, using a YSI 650, and analyzed the monthly mean value from 2010-2015. These monthly mean values showed that pH levels were highest in late spring and early summer months. These data of summer seasons’ correlation to higher pH levels supports our conclusion that less direct sunlight in winter season is linked with a higher acidity and lower pH while more direct sunlight provided in summer season is linked with lower acidity and higher pH levels. The pH levels were lowest during winter, January and February, at a pH of 6.81. The average rose in the spring months of March, April, and May to 7.72 while the average pH peaked during the summer months of June, July, and August was at a high of 7.97. However, it was shown that late spring had consistently higher pH levels. DO levels followed similar trends when investigating those levels. The average DO levels during summer months was 11.4, while the lowest was Fall at 9.88 instead of in expected winter. Although further evidence is needed to connect the fluctuations in DO and chlorophyll via biological processes to these observations of pH. Once this investigation is done, there will be a better understanding of the pH parameters marine organisms can withstand in the Possesion Sound.