Environmentalists say they’re prepared to go to court to stop a planned expansion of the Port of Montreal.

They say the expansion as it stands now breaks the law and vow to protect the western chorus frog and the endangered copper redhorse.

“It is the only fish species we have in Quebec that we find nowhere else in the world,” said Universite de Laval biology professor Louis Bernatchez.

The habitat of the large and unique fish begins south of Montreal and continues along the St. Lawrence River downstream toward Trois Rivieres.

The Port of Montreal wants to expand in the area, building a new cargo port in Contrecoeur, near Sorel.

“It's a bad project,” said environmentalist Daniel Green. “It's bad for the St. Lawrence River. It's bad for our species, it's bad for our drinking water and it's bad for downstream communities.”

According to those fighting off the $750 million expansion project, it's also illegal, due to the federal Species at Risk Act.

“It would destroy critical habitat. The Act doesn't allow the destruction of critical habitat and there's no way in the Act that you can have compensation for destruction,” said Alain Branchaud of SNAP Quebec, the provincial chapter of the Canadian Parks and Wilderness Society.

Two weeks ago, the Port of Montreal announced that the expansion would create thousands of jobs.

Meantime, it disputed the environmental concerns, saying it has a plan “essentially to recreate this area farther downstream where the habits for the copper redhorse fish is more prevalent and of a better quality,” explained Daniel Dagenais, vice-president of operations for the Port of Montreal

With only a few hundred adult copper redhorse left in the St. Lawrence River – Green argues that it’s not an option – the only choice is stopping the project, or moving it somewhere else.

“The Port of Montreal is out of control. The Government of Canada has to come in and told the Port that the environment matters. And that shipping is not more important than the environment,” he said.

Both the federal transport and environment ministries tell CTV they are looking into the issue.

The expansion plan is currently before the Canadian Environmental Assessment Agency. The agency will be accepting comments from the public until March 9. More information here.