COEUR d'ALENE - The Coeur d'Alene, St. Joe, Priest and Spokane rivers and some tributaries will be part of a major drought study by the U.S. Geological Survey.
Hydrologic technicians from the agency are taking measurements from hundreds of streams and rivers across the western U.S. to document and then study the record low flows.
The study could answer whether 2015 might serve as a model for how streams will respond to climate change, and which streams are most vulnerable to warm, dry weather.
The streams selected in North Idaho represent watersheds that derive their base summer flows from snowpack, and those in which base flows are sustained by underlying groundwater, said Timothy Merrick, a spokesman for the USGS in Boise.
"It was also important that sites had a historical record of data to which we can compare this year's data," Merrick said Wednesday. "So they are sites where we have streamgages, had streamgages in the past, or at least collected data for previous studies."
The streamflow and water-temperature measurements started in August and will continue through this month.
"This year's warmer, drier weather provides a preview of how future droughts may impact water resources in the study area," said Chris Konrad, USGS hydrologist and study project chief. "The goal is to provide information to resource managers to help understand differences in how streams respond to drought and plan for future drought impacts throughout the region."
The Press reported earlier this year that snowpack levels this past winter were extremely low compared with long-term averages. Warmer winter temperatures meant more rain than snow, and some places received less precipitation than normal.
With less spring and summer snowmelt at higher elevations, many western rivers and streams reached peak flows earlier than normal. They are now at or near historic low flows.
"This is a large-scale study including six states, nearly 500 streams and rivers and dozens of technicians," said Rich Ferrero, USGS Northwest regional director. "The streamflow data will be important for future drought planning and resource management decisions throughout the western United States."
USGS scientists will compare data with measurements from previous years to find out which rivers and streams depend on snowmelt and groundwater.
They will also learn how low flows and associated higher stream temperatures hurt fish and other aquatic species.
The data will be compiled and analyzed with a summary report of findings planned for publication late next year.
U.S. Geological Survey hydrographer Ryan Smith measures streamflow on the St. Joe River at Red Ives Ranger Station for a regional drought study.