BIG SKY, Mont. — March 4, 2016 — Up to 35 million gallons of sewage water spilled from a storage pond in Big Sky, Montana, into the Gallatin River on Thursday afternoon.

Officials are taking samples from the river to test for turbidity, pathogens, hydrogen, phosphorus, suspended sediment, ammonia and total nitrogen. But the Montana Department of Environmental Quality (DEQ) stressed that the spill released “highly treated reclaimed water” and said there was no risk to human health.

A statement released by the department said: “The combined water is highly treated wastewater, and the expected total nitrogen content of about 7 to 8 mg/L is below the human health standard of 10 mg/L as nitrate. Biochemical oxygen demand (BOD) is below 10 mg/L.”

Posting on its Facebook page, the department revealed that turbidity readings are well above the standard. DEQ water quality specialists will test for E. coli on Monday, with results due back mid-week. Other analysis results for phosphorus, suspended sediment, ammonia, pharmaceuticals, nitrate plus nitrite and total nitrogen will be available after the information is received from the lab during the next few weeks.

Suspended sediment is the main concern, Montana Public Radio reported on Friday.

“As the wastewater is getting into streams it’s picking up a significant sediment load and sediment impacts aquatic life,” explained Kristi Ponozzo, DEQ public policy director.

The outlet pipe for the storage pond flows to the Yellowstone Club golf course, where irrigation of the turf grass is authorized in summer months. Investigators don’t yet know why the pipe broke.