WATER QUALITY IN AN URBAN WETLAND (SPOKANE, WASHINGTON)

This study examines water quality of a small wetland in an urban area in Spokane, Washington. Wetlands can serve as a sink for heavy metals such as lead, zinc and copper. The wetland lies on a moderately graded hill surrounded by roads, homes and businesses. Anthropogenic sources such as vehicle traffic, lawn fertilizers, and road deicer are known to add metals and nutrients to the surrounding environment. We set out to investigate if there were any potentially harmful metals coming into the wetlands from the surrounding areas through runoff. Water at several sites near the roadway, leading to, and in the wetland was tested for pH, alkalinity and various element concentrations. Several dissolved ions were found in higher concentrations in the wetlands and shallow waters around the wetlands. For example, the magnesium and sodium concentrations upstream from the wetland were 17 mg/L and 24 mg/L, respectively, whereas, in the wetland these values reached 27 mg/L and 73 mg/L, respectively. This increase in major ion concentrations is likely the result of evapoconcentration. No metals listed in EPA’s aquatic life criteria (e.g., lead and zinc) for water quality were found in elevated concentrations.