A group of Cambridge residents worried about the environmental impacts of toxic silt build up above the Parkhill Dam will ask the Grand River Conservation Authority to investigate the idea of dredging the river and opening the dam's sluice gates.
Last year, Cambridge resident Bryan Duross led the appeal for action on what he calls an "ecological disaster" created in the more than two decades since the dam's sluice gates were closed in the name of public safety.
The gates were sealed shut in response to a coroner's inquest following the 1998 deaths of Waterloo regional police Const. Dave Nicholson and 12-year-old Mark Gage. They drowned after Gage got trapped in a sluiceway and Nicholson attempted to rescue him.
Typically, sluice gates allow silt and other debris to flow freely down the river where it's disbursed naturally and gradually.
In the more than 20 years since the Parkhill dam gates were closed, Duross says silt has created mucky shallows and an inhospitable environment for the fish that used to thrive there.
He wants the GRCA to at least do core sampling to see what's in the silt, suspecting it contains a cocktail of heavy metals and cancer-causing pollutants like dioxins. If core samples show what he suspects, the GRCA can consider dredging the river where the silt buildup is most prominent.
Sampling done in 2017 as part of a mothballed study of the dam's hydro-generating potential showed "some metals and hydrocarbons" along with elevated zinc levels that may have been naturally present.
In a report released last month, the GRCA says alternatives for addressing sediment transport may be considered in any future significant dam maintenance or modifications.
But Duross doesn't buy the idea that the silt isn't a problem knowing its impact on local fish populations. He fears the silt is high enough near the dam now that during spring runoff, thousands of tons of it could get washed down the river, impacting drinking water quality as far away as Brantford.
The natural environment isn't the only thing that has suffered because of the decision to close the dam gates, he says.
Riverbluffs Park, once home to community events, waterskiing and fishing, has been impacted too.
It has accumulated so much that every year the Cambridge Rowing Club has had to assess the river's depth and consider extending its dock to launch its boats.
Rowing club president Ron Dowhaniuk agrees it's a problem and is adding his voice to the request the GRCA do something about it.
He and the club's 150 members have witnessed the gradual erosion of accessible waterfront and says anyone who wasn't around more than 20 years ago wouldn't be aware of how bad it is.
The silt has accumulated so much that islands are forming where they never were before. The original dock was removed years ago because the water had become so shallow.
"We've had to push our dock out 20 to 25 feet in order to launch a boat," he said. "In another 25 years it could very well be a marshland."
The GRCA has so far resisted calls to investigate the problem further.
In an emailed statement last week, spokesperson for the GRCA Lisa Stocco says the authority is in the early stages of coordination and consultation with Fisheries and Oceans Canada on the matter, but so far there are no plans for further studies or assessments.
In the case of all GRCA dams, including Parkhill Dam, the authority's management program's main objectives are public safety and ensuring dams are maintained to serve their primary purpose, she wrote.
"Any modifications to dams are assessed with respect to their impacts to the environment in balance with dam and public safety," she says. "Recreation is considered an auxiliary benefit."
In a letter responding to the concerns last year, GRCA's manager of infrastructure Katelyn Lynch said the authority recognizes "the sediment has been increasing over the past several decades and is impacting the navigable waters and sport fisheries in the reach upstream of the Parkhill Dam."
However, following the drowning incident and coroner’s inquest, the GRCA determined the trade-off in terms of impacts to the environment was necessary to protect public safety.
Duross' concerns are supported by GRCA board member Pam Wolf, who believes part of the reluctance of the conservation authority to investigate it further is the precedent it could set for the dozens of dams the GRCA owns and operates throughout the watershed.
Wolf says the decision to close the sluice gates at Parkhill was the right decision at the time, but believes now is the time for the GRCA to look at other options to improve public safety around the dam due to the consequences that have become apparent.
"We're not second guessing that decision," she said. It's about seeing the detrimental results and asking now what do we do?
She'll raise the issue again following this week's GRCA board meeting during which a new chair and vice chair will be nominated.
If dredging is ever tabled as a solution, it's believed local groups could launch a public fundraising campaign similar to what the Puslinch Lake homeowner's association did to fund its dredging efforts.
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