Federal officials, Truckee River seeing red
Tuesday evening, a lone man dumped a gallon of liquid off Fanny Bridge into the Truckee River.
Below him, as the liquid hit the river, an orangy-red mist spread its fingers into the current and a widening red plume began floating down the Truckee.
All in the name of science.
Hydrologist Jim Crompton, of the U.S. Geological Survey, poured rhodamine WT dye into the river to begin a time-of-travel study on the Truckee River between the Lake Tahoe Dam and the Little Truckee River near Boca Reservoir.
“We’re trying to see how fast the river runs,” Crompton said.
The study was being done in cooperation with the Truckee Meadows Reclamation Facility, a water treatment plant that serves the Reno area. The primary reason for the experiment is so the facility will know how fast the river flows and would be able to judge the impacts of a toxic spill upstream.
“The concentration and dispersion of dyes provides an understanding of the behavior of soluble contaminants that may be introduced into a stream either by design or as the result of an accidental spill,” said Crompton.
The dye is non-toxic, safe for the environment and will not affect fish or river vegetation, he said. It also disperses until it isn’t visible and can only be detected with specialized instruments.
A crew of about 10 people planned to monitor the river at various points through Tuesday night and into Wednesday. Crompton expected that the dye would reach Truckee about 5 a.m. and be at the Little Truckee River’s inlet into the Truckee River sometime Wednesday afternoon.
The Lahontan Regional Water Quality Control Board required the USGS to conduct the experiment at night so the public would not see the dye in the river.
“There is an aesthetic quality mandate for the Truckee River,” Crompton said.
This is the first time the USGS has measured the speed of the 25-mile stretch of river between Tahoe City and Boca, although it has measured the speed near Glenshire in the 1980s.
“This will be the first time we’ve done this section of river,” he said.
The USGS measured the speed of the river from Mogul, Nev. to the Marble Bluff Dam in Nixon, Nev. in April and August, finding the speed of the river to be 1 mph and 3 mph, respectively.
He said the Truckee’s volume of so many cubic feet per second is measured daily, but its speed is not.
He compared it to a car driving down the highway between two points. Knowing the speed limit does not tell a person how fast that car will actually be able to drive the distance. The car’s trip must be timed.
Knowing the volume of water in a river does not tell how fast it is flowing, but the red dye experiment will be able to measure the amount of time a particular piece of water takes to travel.
“It’s like putting a fluorescent orange car on the highway,” he said.
The information is not being gathered for the Truckee River model that is used for the negotiations on the Truckee River Operating Agreement, but it is available to them. The federal water master has asked for the results, Crompton said.
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