Jones Lake in Moncton can be a popular spot on a warm sunny day, but recently, something else has been getting people's attention.

Dozens of dead fish have washed up along the shoreline, and while officials haven't released any information as to what's causing the fish to die some residents say they aren't surprised it's happening.

“I come down here four or five times a week and sit … just watch the birds and the lake and enjoy the outside,” said resident Michael Leaman. “It's actually an artificial lake and the water doesn't flow out so it doesn't get a chance to flush itself and that's just a breeding ground.”

Ron Joseph visits the lake every day to watch the birds and take photos.

He says he first noticed the issue last week.

“I noticed fish just floating on the shoreline and the fish, they looked like they weren't dead very long, but they were swelling up,” Joseph said.

Joseph says he contacted the city on Friday after conditions at the lake seemed to be getting worse.

“The water started to stink on the weekend,” Joseph said. “It’s a smell, a really foul smell, and it’s still there; you can probably smell it standing here.”

A spokesperson for the city says they have been notified about the fish and that they immediately contacted the Department of Environment who have since opened an investigation into the matter.

CTV News contacted the department for comment, but but did not hear back by news time.

“My concern was that, if there's something in the water that could be passed on to the natural wildlife down here … like birds and whatever else is in the water,” said Joseph.

The Peticodiac Watershed Alliance has labelled the lake as a “secondary contact recreation” only area, meaning they do not encourage anyone to swim in the lake, but they do allow for activities such as canoeing and kayaking.

“There are a lot of families in this area and that’s a problem because with kids and so on, you can't always be watching them all the time,” said Leaman.

For now, residents are left with more questions than answers until the investigation is finished.

With files from CTV Atlantic’s Eilish Bonang.