TACOMA — Scientists from the U.S. Geological Survey are using a fluorescent red dye to determine the complexity of the channel in the Elwha River as part of a larger effort to define conditions in the river since the removal of two dams.
Scientists say the dye they began using this week is harmless.
“You might see a reddish tint to the water during the week of Sept. 29, but it’s nothing to worry about,” said Rich Sheibley, USGS hydrologist and leader of the dye study.
“Scientific use of this dye is very common and has been shown to be harmless to aquatic life and human health.”
Rhodamine WT, the fluorescent red dye used in this study and commonly used in other hydrologic studies, is nontoxic and safe for the environment, according to the USGS.
The dye is being released at a point just downstream of the diversion on the Elwha and monitored at downstream locations by USGS hydrologists.
The study will provide estimates of water travel time between points on the river and provide information about the river channel’s complexity by modeling the response of the dye at a downstream location.
Results will be compared with a similar experiment done before the dams were removed.
The final 30 feet of Glines Canyon Dam was removed this summer. Elwha Dam was demolished by March 2012.
The study is part of ongoing scientific work by the USGS, the National Oceanic and Atmospheric Administration, the Lower Elwha Klallam tribe, the National Park Service and the Bureau of Reclamation to document conditions in the Elwha River prior to and after the removal of Glines Canyon and Elwha dams.
Removal of the two dams, which were built 1912-27, opened about 70 miles of river habitat — including tributaries to the 40-mile river — for salmon and other species.