Following a provincial order to determine the environmental impact of a four-and-a-half-year long accidental discharge of stormwater runoff and sanitary sewage into Chedoke Creek and Cootes Paradise, a new consultant’s report is advising City of Hamilton officials not to remediate the areas in question.
Due to a bypass gate left unintentionally open at a combined sewage overflow (CSO) tank, Hamilton officials estimated that approximately 24 billion litres of combined sewage leaked from 2014 to 2018 into Chedoke Creek. The creek in turn outlets at the south shore of Cootes Paradise Marsh, part of a nature reserve owned and managed by the Royal Botanical Gardens.
The April 22 environmental impact evaluation report prepared by SLR Consulting Ltd. found that concentrations of potential contaminants related to surface water quality were “comparable” to concentrations before the spill, supporting the conclusion that “there is no evidence of long-term impact on Cootes Paradise.” Based on annual mean concentrations, changes in surface water quality in Cootes Paradise during the CSO discharge were limited to E. coli and total phosphorus.
“Given that post-discharge levels of contaminants in surface water (except ammonia and dissolved oxygen, which are components of landfill leachate) appear consistent with pre-discharge levels, no remaining adverse impacts to Cootes Paradise as a result of the Main/King CSO discharge persist,” the report states.
Some city councillors who discussed the report at an April 29 virtual meeting seemed to take away the impression that the impacted environment was in such a poor state prior to the massive leak that the additional damage barely registered.
“Cootes Paradise is not a pristine water course. It has been impacted over the years,” said Andrew Grice, Director of the Hamilton Water Public Works Department, who noted that the water quality has in fact improved over the last 50 years, particularly by controlling elements such as the CSO tank that caused the leak.
Other councillors, such as Ward 3 Councillor Nrinder Nann, indicated some concern that the water course analysis used datasets from as far back as the mid-1990s.
“In some areas it may be difficult to draw conclusions when you have just one, two, three data points,” Grice told councillors.
In terms of sediment quality, the consultant’s report found no changes in select nutrients and metals concentrations when comparing samples from before and after the massive leak. Similar findings of no discernable differences were noted for impacts to aquatic vegetation and fish communities inhabiting the areas.
The Cootes Paradise leak, or what became known as “Sewergate” due to a lapse in municipal disclosure about the long-term leakage, seems to have bolstered the City of Hamilton’s efforts to hire a water quality technologist. The individual would develop a water quality program to monitor all of Hamilton’s watercourses that receive discharges from municipal infrastructure.
“That will be a really big step for us,” said Grice, who noted the application process has closed but that the ongoing pandemic has brought fresh challenges to the City’s interviewing process for the new role.