THURSDAY, OCTOBER 15, 2026|No. 18835
Environment · Nova Scotia

Fish populations show signs of recovery in Sydney's remediated tar ponds

Fish are returning to brooks near Sydney's former tar ponds and coke ovens sites, a positive indicator following a significant $400 million environmental cleanup effort.

Open Hearth Park, formerly the Sydney tar ponds, now features recreational spaces and a recovering ecosystem.
Open Hearth Park, formerly the Sydney tar ponds, now features recreational spaces and a recovering ecosystem.
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Officials say fish are returning and healthy after Sydney tar ponds cleanup

It's been 13 years since the governments of Canada and Nova Scotia spent $400 million to clean up the notorious Sydney tar ponds and coke ovens sites, left over from a century's worth of industrial coal and steel production, and fish are now showing signs of bouncing back in local brooks.

They say small mummichogs no longer showing abnormalities, trout showing up

Donnie Burke, senior director with Build Nova Scotia, says independent water quality testing shows that remediation of the former Sydney tar ponds and coke ovens sites is working.

Fish are returning to the brooks around the former tar ponds and coke ovens sites in Sydney, N.S., and officials say that is a positive sign after the cleanup of a century's worth of the steel and coal industries in Cape Breton.

The $400-million cleanup was done by the Sydney Tar Ponds Agency, which was later folded into Nova Scotia Lands and now falls under Build Nova Scotia, the agency tasked with monitoring water quality in the brooks running through the former industrial sites.

Donnie Burke, a senior director with the agency, said results from an independent engineering firm show the remediation efforts are working.

"Everything that we're seeing to date is trending stable or improving, so that's a wonderful thing," he said during a recent tour.

The coke ovens ground was covered with leftover slag rock from the former steel plant, while the notorious tar ponds, next door to the coke ovens and once known as the most toxic waste site in Canada, were encased in cement.

Coke Ovens Brook, Wash Brook and Muggah Creek were also cleaned up and the adjacent sites were landscaped to direct surface water into the brooks, while groundwater from the coke ovens land is directed into a treatment plant before going back into the brooks.

Both sites were then covered with topsoil and grass.

The former tar ponds are now known as Open Hearth Park, hosting football and soccer fields, a playground, walking paths and open space.

The coke ovens site is an open field that has been used for cricket, walking and snowmobiling in winter.

Burke said water testing shows the tar ponds cap is not releasing any toxins.

The former coke ovens site occasionally produces a spike in heavy metals or industrial chemicals, usually after a heavy rain, but the monitoring system catches those and the water treatment process is adjusted accordingly, he said.

"There's all kinds of little anomalies," Burke said. "We see a little more fluctuation here, but for all intents and purposes, this has been stable or improving since the cover has gone on."

Water is tested in the brooks and under the former coke ovens cap through wells scattered around the sites.

A recent study out of Cape Breton University found that a small species of fish had returned to the brooks and Burke said provincial staff recently noticed trout eggs and fry in Coke Ovens Brook.

"Who would have thought that 20 years ago, that trout would live here?" he said.

Katherine Jones, a biology professor at CBU, studied mummichogs living with poor health in the tar ponds before the cleanup.

Last year she supervised fourth-year student Hannah MacKinnon's pilot study to see if their health had improved. Jones said MacKinnon found the symptoms they displayed previously have disappeared.

"We didn't see fin rot or fin erosion or bone abnormalities, so overall, the state of the health of these fish seems to be much better than prior to the remediation," she said.

'Trending in the right direction' — Burke

Jones said it would take more studies to determine whether local fish are still being affected by the remediated industrial sites and she'd like to test their DNA to see if they are related to the fish who lived there previously or whether they have migrated in from elsewhere.

Burke said the government was committed to monitoring the sites for 25 years after the cleanup and the results are posted regularly on Build Nova Scotia's website.

The monitoring is about halfway done "and everything seems to be trending in the right direction," he said.

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