A new pollution monitoring program has found that Victoria's Inner Harbour is the most polluted body of water along B.C.'s coastline.

The data comes from a coast-wide program called PollutionTracker, which was created by Ocean Wise, a global conservation group based out of the Vancouver Aquarium.

The program collected sediment and mussel samples from 55 coastal locations between 2015 and 2017, including four sites within Victoria's harbour.

High levels of contaminants were found in the samples, including now-banned polychlorinated biphenyl – a chemical found in things like coolant, flame retardant, hydrocarbons and pharmaceuticals.

The four sites in the harbour, which is under the jurisdiction of Transport Canada, were found among the top five most-contaminated sites in B.C.

The City of Victoria said while the results aren't pretty, they're not surprising considering the harbour's industrial history.

"It's upsetting and concerning," said Victoria Coun. Charlayne Thornton-Joe. "I was looking up photos from the late 1800s and you can see the industry that was being done, whether it was ship-building, whether it was mills. All that existed back then, and of course back then there was no consideration of the environment."

The harbour's geography, with its shallow and slow-moving water, could also be partly to blame as pollutants more or less stay put and get swallowed by fish and other animals.

"They really reflect what we've released or used historically," said Peter Ross, a researcher with Ocean Wise. "A lot of these chemicals don't break down. We find them persisting in the environment, we find them accumulating in killer whale food webs."

Ocean Wise said the threat to endangered southern resident killer whales, which frequent the waters off Victoria, is of particular concern.

"PCB levels in habitat, including sediments, are high enough to contaminate the food chain and deliver PCB's to our killer whales," said Ross.

The organization said the data doesn't suggest the water is unsafe for humans, but it will act as a baseline to measure future improvements.