A warming climate could diminish the volume of water in the Spokane Valley-Rathdrum Prairie Aquifer, which supplies drinking water to most of Spokane and Kootenai counties.
A Boise State University assistant professor, Venkataramana Sridhair, ran different modeling scenarios to analyze how climate change would affect the aquifer.
Over the next 50 years, temperatures are projected to rise about half a degree per decade in the Spokane River Basin as a result of higher carbon dioxide levels and other so-called greenhouse gases. Annual precipitation should stay roughly the same. But even with stable precipitation, the aquifer could experience declines, said Sridhair, an engineer who specializes in water resources.
The warmer temperatures will trigger more rain-on-snow events, he said. Instead of snow piling up in the mountains, the rain will rush over frozen ground, with less reaching the groundwater to recharge the aquifer, Sridhair said.
“More of it falls as liquid precipitation,” he said. “It doesn’t get into the system.”
Sridhair presented the study results Monday in Coeur d’Alene to members of an aquifer advisory committee established by the state of Idaho. The group works on long-range planning issues for the aquifer, which supplies drinking water for more than 500,000 of the region’s residents. The aquifer – often described as a bathtub full of gravel with water flowing through – covers more than 325 square miles, extending from the southern part of Lake Pend Oreille to the Little Spokane River.
At the moment, very little water-storage capacity exists in the Spokane basin, noted Paul Klatt, a local engineer and committee member. So, there aren’t opportunities to store the water from rain-on-snow events for future use, he said.