One city official said the sewage water that leaked into Hamilton Harbour nearly 26 years ago is an "anomalous" incident and the environmental effects are likely to be "relatively small."

Nick Winters, director of Hamilton Water, said at a press conference on Wednesday morning: "Knowing that something like this could happen during that time without our knowledge does not make any of us feel comfortable."

The City of Hamilton announced Tuesday afternoon that it had discovered a sewage leak in the harbour of Lake Ontario while working on another project.

The city also stated that the leak was discovered at the northeast corner of Wentworth Street North and Burlington Street East and had gone undetected since 1996. Winters said the leak resulted from a contractor accidentally causing a hole in a combined sewer pipe while working on a major water project.

"The issue, of course, is that there are huge water mains behind me here underground running along Wentworth Street North and reaching the harbourfront. And on the harbourfront, there is a storm sewer outfall, so any flow from this pipe comes out into the harbour," Winters said, adding that this source is submerged 100 percent of the time... so nothing would be visible... it would have shown them that this leak was occurring over a period of time.

The city said the city's drinking water was not affected and the overall risk to the public is "very low."

Also, Winters said he believes that when the main water project was being implemented, there was an addition made that created a hole in the combined sewers based on an inaccurate project drawing by the engineers.