The Tsuu T'ina nation blames vandals for blocking its Redwood Meadows sewage line, causing raw waste to be diverted into a forest near the Elbow River.
Untreated human waste from the bedroom community west of Calgary — which is leased from the First Nation — flowed for almost two weeks directly into the woods roughly 500 metres from the Elbow River, a source of Calgary’s drinking water.
The problem has now been fixed and the sewage is flowing properly into a lagoon on the reserve, Tsuu T’ina officials said. But Scott Mossop, who works for the company hired to take care of Redwood Meadows’ waste, said he is still very worried about the state of the system.
Mossop said sewage from Redwood Meadows flows by pipe five kilometers to lagoons on the reserve. But then the sewage just keeps flowing right on through them, he said.
"It’s not treated. That I know for sure. It just goes out into the field here," he said, showing the system to a CBC News reporter.
"All these pipes and stuff are supposed to be for aeration which is an important part of sewage treatment system. They haven't worked in years."
The deficiencies could someday affect Calgary’s drinking water, he said.
Tsuu T’ina officials dispute those claims.
Band administrator Kevin Littlelight said waste water is treated at the lagoons, and the system is working fine.
"No, there are no concerns about that. It's worked beyond the ages and it’s going to continue working," he said.
CBC News contacted officials at the City of Calgary, the province and the federal government.
All three levels of government said they have no concerns.