A pipe below a holding pond in Big Sky, Montana, broke Thursday spilling an estimated 35 million gallons of sewage water into the West Fork of the Gallatin River.
The treated sewage water was flowing into Second Yellow Mule Creek and then into the south branch of the West Fork of the Gallatin River.
According to a written statement from the Montana Department of Environmental Quality, the spill does not pose a threat to human health.
DEQ said suspended sediment is the main water concern, as the wastewater picks up sediment on its way downstream.
DEQ said it will work with local and other state officials on a sampling and monitoring plan that will test for pathogens, hydrogen, phosphorus, suspended sediment, ammonia and total nitrogen, according to the statement.
The cause of the spill is under investigation.
The spill ended up discovered by a Yellowstone Club employee.
The club estimated the spill would end up contained within 24 hours.
Gallatin County Undersheriff Dan Springer said he understood that it was not immediately possible to fix or plug the pipe. He added, though, that he also understood there was no indication of potential health issues.
The DEQ also said they treated the water. The expected total nitrogen content of about 7 milligrams to 8 milligrams per liter is below the human health standard of 10 milligrams per liter. The state said the pipe flows to the Yellowstone Club golf course for irrigation in the summer months.
“The water is treated to a high level and not a risk to human contact,” the club said.
Photos taken Thursday afternoon and released by the DEQ show brown water flowing through the creek. The river was still running brown late Thursday night. The club in its release explained the coloration by saying the leaked water was picking up sediment on its way downhill and kicking up dirt in the connecting waterways.
While the DEQ and the Yellowstone Club stressed the spill posed no health risks to humans, a Trout Unlimited official said a risk to fish may exist.