The reddish substance that drained into the Boise River on Wednesday evening was a dye used by a dairy to test its equipment, according to Boise Fire Department spokeswoman Tammy Barry.
It’s unclear how the dye made its way into a storm drain, and ultimately the Boise River, Barry said Thursday. An Ada County Highway District contractor pumped out the substance Wednesday night. How much dye and how long it was there is unclear, Barry said. The substance is nontoxic and nonflammable, Barry said.
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Barry said a hazmat crew was dispatched shortly after 5 p.m. Wednesday to the American Boulevard bridge. The Idaho Department of Environmental Quality had called in about a reddish substance going into the Boise River from a storm drain.
The fire department asked Boise police to evacuate the wave at the whitewater park while crews tested the substance.
Staff from the ACHD, Idaho Power and Boise Police Department joined the fire department on the scene Wednesday. The power utility became involved as a precautionary measure, due to concerns that the unknown substance could reach large underground transformers.