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.