CHARLOTTETOWN -- Prince Edward Island's premier has come out against a Nova Scotia pulp mill's plan to pump effluent into the Northumberland Strait.

Wade MacLauchlan has voiced his disapproval of Northern Pulp's proposal in a letter to Nova Scotia Premier Stephen McNeil and to federal Environment Minister Catherine McKenna.

MacLauchlan says he shares concerns by Nova Scotia and P.E.I. fishermen that an outflow pipe could have "unintended consequences for our commercial fishery and aquaculture industries" in the strait.

"An effluent pipe that would allow as much as 75,000 cubic metres of fresh warm water to be directed daily into the Northumberland Strait is not a project that our government will support as proposed," he wrote in the letter, released Tuesday by his office.

The Pictou, N.S., mill -- which is across the strait from eastern P.E.I. -- has been told by the Nova Scotia government to replace its effluent treatment plant by 2020.

The company announced plans for a new plant last month and is to submit an environmental assessment to Nova Scotia's Environment Department this summer.

According to Northern Pulp's plan, the effluent would be treated at a new facility near the mill using a system that would meet all federal environmental standards for suspended solids and oxygen depletion.

The effluent would be carried by polyethylene pipe across Pictou Harbour and released through six dispersal pipes into the strait.

MacLauchlan said he's confident everyone can agree that any development that risks threatening the habitat of lobster and other species -- and therefore the livelihood of fishermen and their families -- "cannot proceed."

"I understand that a Level 1 environmental assessment will be conducted this summer. I ask that a more comprehensive assessment take place and that the impact on Island fisheries is taken into consideration as part of this work."

A spokesman for McNeil said there would be "no comment today," adding only that Environment Minister Iain Rankin is "managing the file."