About a million gallons of contaminated mine water spilled into a tributary of the Animas River in San Juan County on Wednesday.
Workers with the Environmental Protection Agency triggered the spill at Gold King Mine near Silverton while investigation contamination at the site.
The EPA is warning people to stay out of the Animas River until the wastewater flows downstream.
Jonathan Thompson, a senior editor with environmental magazine High Country News, tells KUNC the pollution has turned the river bright orange.
"The river normally is a nice green color, sort of deep green," said Thompson. "And right now where that has hit. It is bright orange. It’s like orange crush, but a really thick orange crush."
La Plata County says the acidic mine water contains high levels of sediment and metals.
Durango shutoff water it gets from the river and the county notified agricultural users to shutoff water intake.
Colorado Parks and Wildlife says it’s watching the affects the spill could have on fish and other animals.