USGS to Conduct Dye Tracer and Aerial Mapping Surveys on Kootenai River

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BONNERS FERRY, Idaho — From Sept. 24 through 29, scientists from the U.S. Geological Survey will conduct dye tracer and aerial mapping studies on northern Idaho’s Kootenai River. Data from the studies will support Idaho Department of Fish and Game and Kootenai Tribe of Idaho fisheries and river restoration projects.

Aerial view of red dye in the Kootenai River
Aerial view of a USGS dye tracer study done on the Kootenai River in Idaho.
(Public domain.)

USGS scientists will inject a harmless, bright red fluorescent dye into the Kootenai River downstream of its confluence with Deep Creek near Bonners Ferry. The goal of the dye study is to understand where and how fast larval sturgeon and burbot move downstream to Kootenay Lake in British Columbia.

“Data from the dye tracer study will be instrumental in helping us better understand how and where young sturgeon and burbot move in the river after they hatch from their eggs,” said T.J. Ross, Senior Fisheries Research Biologist with IDFG. “This knowledge will get us one step closer to providing the conditions necessary for these fish to naturally reproduce in the Kootenai River as they once did.”

The red dye is approved for use as a water tracer by the U.S. Environmental Protection Agency and is harmless to people, fish and plants at the concentration being used for this study. For a few hours after the start of the study, several miles of the river will appear reddish in color because of the dye. The red color will dissipate rapidly and should disappear after it travels downstream near the town of Copeland.

Citizens may also notice an airplane regularly passing over the river. The airplane will be equipped with Light Detection and Ranging technology to map the land surface around the river (topography) and under the water (bathymetry) as part of the USGS 3D Elevation Program. This study will be one of the first to combine topographic and bathymetric lidar data collection.

“The lidar flight will provide detailed elevation data in areas that would otherwise be challenging to survey,” said Susan Ireland, Fish and Wildlife Department Director for the Kootenai Tribe. “The data will support our existing habitat restoration projects and could be useful for future restoration project design, implementation and biological assessment work.”

USGS scientists will use the data collected from both studies to improve computer models that let fisheries managers simulate various river conditions to see how those conditions might affect fish spawning. The scientists also hope to be able to use lidar imagery to estimate the river’s water-quality conditions such as turbidity. If successful, this innovation would save time and money compared with manual water-quality sampling.