Carey Gazis (Geological Sciences)
The Spokane River, a tributary of the Columbia River, is the main river that flows through Eastern Washington and through the City of Spokane. This river serves as the primary source of recharge for the Spokane Valley–Rathdrum Prairie Aquifer (SVRP), providing water for Spokane, Post Falls, and Lake Coeur D’Alene. Historical mining at Lake Coeur D’Alene that occurred in the 19th and 20th centuries is believed to be one potential source of pollution in the river. While research has analyzed contaminants in the Spokane River, there has been a lack pollution measurements consistently over time. To assess the impact of historical mining on the Spokane River, researchers collected samples of river water at five separate locations between Gateway Regional Park and Riverside State Park on a single day. Three of these sampling sites were upriver from Spokane, one within the city, and one downstream of Spokane. At Central Washington University, the samples were analyzed with an inductively coupled plasma mass spectrometer to determine concentrations of heavy metals. Calcium, measured between 6 parts-per-million (ppm) and 25 ppm seem to be consistent with prior measurements made in the SRVP of 30 ppm of Calcium. Waters sampled closer to the Washington- Idaho border are more dilute, with the lowest total dissolved solids. Despite this dilution, these samples appear to contain higher concentrations of lead, zinc, and iron. More samples need to be tested at each site to give a better understanding of chemical variability in the Spokane River.
Keywords: Spokane River, Spectrometry, Mining