Two women frustrated with the city's inaction on sewage debris washing up on the shores of Bayfront Park took matters into their own hands this weekend – by spending most of it floating in a raft on the water in protest.

By Monday morning, city crews had shut down the Waterfront Trail and started cleanup efforts, removing bags of waste like needles and tampons that peppered the shore.

But that only came weeks after activists Kristen Villebrun and Wendy Bush starting pressing the city to do something about the mess.

Heavy rains on Oct. 28 overwhelmed three key parts of the city's storm-water management system, allowing sewage and storm runoff to flow into the harbour. Waste-water bypassed the Woodward treatment plant and two of the city's nine massive overflow holding tanks overflowed.

The "most compelling theory," said Hamilton Water head Dan McKinnon is that storm as the source of the material. But he also said he said it's "unlikely we'll ever know with 100 per cent certainty" where the waste came from.

He said miscommunication led to the cleanup delay.

It took us going out on a floating device and risking our health and safety, and it shouldn't come to that. - Kristen Villebrum

On Monday, the stench of sewage still hung heavy in the air on the Waterfront Trail.

"That's what we were out there smelling," Villebrun said. "It was almost like floating in a septic tank."

"It took us going out on a floating device and risking our health and safety, and it shouldn't come to that. They need to respond to complaints."

The two first started noticing the debris at the end of October while erecting Inukshuks along the trail, as part of an awareness project for Canada's missing and murdered aboriginal women.

'Something needed to happen immediately'

While building, they found needles, tampon applicators and raw sewage. "It was disgusting," Villebrun said. "Something needed to happen immediately."

Villebrun contacted the city, but didn't make much headway, she says. "It took a lot of arguing," she said. "One guy said it 'wasn't that bad of an issue.'"

Hamilton activists Kristen Villebrun and Wendy Bush spent much of the weekend on a raft by the Waterfront Trail to draw attention to garbage including needles and tampon applicators that had washed up on the shore. (Kristen Villebrun)

McKinnon told CBC News city crews did respond about Villebrun's concerns in the Princess Point area in early November, and did drag off bags of waste from that area.

Crews didn't search anywhere farther than that, he said – adding that it's "not necessarily the case" that the city didn't respond right away.

Ward 5 Coun. Chad Collins wanted to know why the mess had gotten to that level, and it took the city so long to clean it up.

Debris has washed ashore often over the years along the beach strip, from dead fish to medical waste from the GTA, Collins said. But the city still has no protocol for when it cleans up the waterfront.

"It seemed like this was the first time that it ever happened and it's on the news and it's on TV and it sounded like we didn't have a standard operating procedure," he said.

Where is this sewage coming from?

So if sewage is washing up on the shore of the waterfront trail, where exactly is it coming from? "I don't think anyone can say with certainty," McKinnon said.

During particularly intense rainstorms, sometimes wastewater bypasses the full treatment system at the Woodward water plant. That happened in this case.

Nine special overflow tanks at different areas of the city hold back much of the wastewater in those situations, but two of the west-end tanks overflowed on Oct. 28 too, McKinnon said.

Even with the overflow tanks, Collins said, debris like that found on the weekend still happens.

"We have reduced the number of times we have bypasses from the sewage treatment or when we see untreated storm and sewer that flow through even to Red Hill Creek," he said.

Needles and tampons should be filtered out

However those tanks are built to filter out "floatables" such as needles, tampons and condoms, so now water officials are checking the tanks to determine whether the tanks failed or the waste floated from elsewhere.

"The biggest question here is where this is coming from, and the higher ups are trying to figure that out," said Steve Hasselman, the park's superintendent.

"I have little kids too. I don't want kids down here stepping on needles."

McKinnon said Hamilton's drinking water is safe, and the intake pipe is far out in Lake Ontario away from the debris.

He also said that Hamilton is investing millions every year to improve its water system, and has for decades. The overflow tanks are an example — the most recent was installed about two years ago.

Officials expect the Waterfront Trail will reopen Tuesday.

adam.carter@cbc.ca