The Evolution of the Forest River Water Quality Due to Anthropogenic Impacts

Abstract

The northeast United States faces harsh winters, resulting in the widespread application of road salts (NaCl) beginning in the1960’s. Road salt is a chemical deicing agent, which enters into streams and ponds via runoff and infiltration into the groundwater system. The widespread application of salt to roads, walkways, and parking lots is known to pollute urban watersheds. The focus of this study is Ducks Pond, located in the Forest River watershed in Salem, MA, and is part of an ongoing investigation to monitor the effect of development in and around the reservation. Pure water cannot transmit an electrical current. However, the ability of an aqueous solution to conduct a current is a measurable physical property known as its conductivity. Because conductivity is temperature dependent, measurements must be taken at or standardized to 25° Celsius, for comparison. With increasing concentrations of chloride from salt application through runoff, specific conductance will also increase showing a positive relationship which can be measured using a multiparameter probe. Previous water quality data, obtained in 2018, showed Ducks Pond was completely clear of chloride ions while other water bodies within the watershed, all walking distance of each other, had high concentrations. The lack of salt pollution in Ducks Pond is hypothesized to be the result of natural isolation by topographic highs, in combination with a railroad embankment that effectively cut off the pond from the rest of the watershed. To add to existing data, specific conductance, temperature, dissolved oxygen, and pH were measured at 5 locations in the fall of 2020 and the spring of 2021 using a YSI 6600 multiparameter sonde. The results are consistent with the data from 2018. All results support the hypothesis that Ducks Pond is a subwatershed, which is isolated from pollution both naturally and as a result of construction of the Boston and Maine Railroad embankment in the late 1800’s.