Tests showed harmful E. coli counts in Chedoke Creek spiked dangerously – at one point 900 times higher than safe levels for paddling – over the four years that sewage escaped undetected from a city tank.

That's 9,000 times higher than the threshold for safe swimming.

"With those levels, you're obviously talking about raw sewage in the water," said Mark Mattson, an environmental lawyer and founder of Lake Ontario Waterkeeper. "If you see that, you have a reasonable excuse to call the (provincial) spills action line."

So why did it take more than four years to discover Hamilton's 24-billion-litre sewage leak?

The Spectator revealed two weeks ago the city hid the extent of a four-year spill that leaked 10,000 Olympic pools worth of sewage into a west Hamilton creek via a tank gate inexplicably left open from January 2014 to July 2018.

The city says it does not know why the gate was left open and electronic monitoring did not reveal the leak. It was only found after a physical inspection spurred by a public spill complaint to the province.

But annual water tests in Chedoke Creek, obtained from the Hamilton Conservation Authority, show E. coli bacteria counts spiked to grossly high levels in each year the sewage gate was open.

E. coli bacteria counts during annual water tests in Chedoke Creek | Hamilton Conservation Authority

The test results, which measure the bacteria in colony-forming units (CFU), often fluctuated from the hundreds to the hundreds of thousands — sometimes in response to wet versus dry weather.

But some results approached or surpassed 1 million CFU/100 mL annually between 2014 and 2017, with the highest result topping 1.8 million in the latter year.

By the time the stinky spill was reported and confirmed by authorities in July 2018, a test sample showed a record 3.4 million CFU/100 mL, sparking a provincial investigation.

By contrast, the government threshold for safe "recreational water use" like paddling is 2,000 CFU/100 mL.

It is also worth noting the public health department shuts down beaches for swimming when E. coli levels top a mere 200 CFU/100 mL. Even at that level, there's a chance ingesting the harmful bacteria could cause stomach cramps, diarrhea, nausea and vomiting.

The city has long posted signs warning against touching the water in Chedoke Creek — even before the spill — because of historical pollution.

But some residents still explore the creek by canoe and kayak — and far more paddle at nearby Princess Point in Cootes Paradise.

Chedoke Creek empties into the popular marsh near the canoe put-in dock. At the height of the spill in July 2018, E. coli tests conducted near the public boat launch were as high as 128,000 CFU/100 mL. (When the spill was confirmed, the boat dock was pulled from the water.)

Those are worrisome results in either case, said Mattson, whose organization pushes for sewer overflow prevention and public notification. "Would you want to risk falling out of your canoe at that point? Or letting your dog play in the water?"

The E. coli test results — from Chedoke and other area creeks — were collected by the conservation authority in annual reports as part of the greater Hamilton Harbour Remedial Action Plan (RAP).

That partnership of governments and stewardship agencies is tasked with cleaning up the polluted harbour.

All of those partners — including the city — knew there was a sewage contamination problem earlier than 2018, said Tys Theijsmeijer of the Royal Botanical Gardens, which manages Cootes Paradise.

"We were all seeing the test results that didn't make sense. We were doing good work, but the results were slipping, not improving," he said. "We were looking for answers ... (but) not in the right place."

Kristin O'Connor, who co-ordinates the Hamilton RAP, said she arranged a special meeting of partners in March of 2018 to co-ordinate a more intensive search for rogue sewage.

"However, at the time our focus was on looking for other unmanaged sources (of sewage), not an assumption of a CSO control failure," she said via email.

Non-scientist citizens also urged the city to take action as early as 2016.

Hamilton Conservation Authority table showing creek samples that measured E. coli in the water between April 2017 and March 2018. | Hamilton Conservation Authority

Kristen Villebrun staged a protest on a raft in Hamilton harbour in 2015 to draw attention to floating sewage debris like needles and tampons that was building up on the harbour shoreline.

But Villebrun said she and a friend also "tracked back" evidence of flushed detritus all the way to Cootes and the mouth of Chedoke. She said they reported their concerns to the city in 2016. "When you smell that smell, you know what it is. It's s--t," she said. "But what we said was dismissed."

Loading... Loading... Loading... Loading... Loading... Loading...

Public works head Dan McKinnon said the city has long acknowledged sewage problems in Chedoke. For example, the city has been searching out and fixing illegal sewer hookups on the west Mountain for years.

He acknowledged the city had a member on the Hamilton harbour RAP committee with access to the creek test results and that there was general agreement "something was happening" in Chedoke Creek.

But McKinnon said the city's electronic monitoring system for its sewage-trapping tanks did not obviously show anything amiss with the now-infamous partly open tank gate.

Citizens, outside experts and even councillors have expressed outrage upon learning the city did not do physical inspections of the tank gate in question. From now on, that will happen regularly, said McKinnon.

But until the spill was discovered, "it was not on the maintenance check list."

Part of the challenge in the early sewage search was that Chedoke Creek is polluted in so many different ways, said Scott Peck, watershed planning director for the conservation authority.

The creek sucks up toxic overflow from parking lots. It runs through concrete channels along Highway 403 and right beside the old west Hamilton dump.

READ MORE ON SEWERGATE:

Sewergate: Everything we know so far

City shares 'chronology' of west Hamilton sewage spill

Andrew Dreschel: Hamilton city council voted for Sewergate secrecy on verge of 2018 election

It also receives a regular mix of storm water mixed with sewage from combined sewers that overflow upstream of the latest problem tank. That includes an outfall pipe near Aberdeen Avenue that overflowed in storms or heavy rain 42 times in 2017 alone.

A single storm-fuelled combined sewer overflow can cause notable spikes in E. coli counts.

Historical water testing data provided by the authority shows annual E. coli tests routinely failed the safe paddling test going back to 1999. Still, average annual results from 2014 to 2017 are notably higher.

"We knew there was an issue there. But whether it was overflows, illegal hookups or something else upstream, we did not know," Peck said. "We were doing more testing to try to pinpoint the problem."

mvandongen@thespec.com

905-526-3241 | @Mattatthespec