Three GSI staff members—John Porcello, Walt Burt, and Jake Gorski—published a feature article in the December issue of The Water Report about their efforts to determine the cause of long-term declines in summer streamflows of the Spokane River. The article was co-authored by GSI client Ty Wick of the Spokane Aquifer Joint Board (SAJB).
The article describes GSI’s recent forensic study in the Spokane/Coeur d’Alene area, which retraced the history of surface and groundwater use, urban and agricultural water demands, streamflows, and climate dating back to 1900. The study found that while water practices during the first half of the 20th century likely contributed directly to declines in river flows during those years, further declines in streamflows in the past are now strongly appearing to be the result of a climate-change influence. These declines are persisting in spite of significant improvements in water supply management and stable (if not rising) groundwater levels during the past 2 to 3 decades—two influences that should be helping to increase the river’s summer season flows. The climate-change influence appears to be overriding any potential gains from improved water supply management and stable or rising groundwater levels.
This work demonstrates how a thorough and complete analysis of historical hydrology and water uses provides important context and value to local water communities by illustrating causes and effects that might not be evident from a review of hydrologic and water use data during a much shorter and more recent time period.