By PHUONG LE, Associated Press

DES MOINES — All recreational and commercial vessels would be banned from releasing sewage, treated or untreated, into Puget Sound waters under a proposal announced Thursday by state regulators.

The Department of Ecology asked the U.S. Environmental Protection Agency to designate about 2,300 square miles as a “no discharge zone” in an effort to improve water quality and protect shellfish beds and swimming beaches from harmful bacteria.

If approved, boats would be prohibited from pumping sewage into waters from near Sequim to south Puget Sound to the Canadian border, and include Lake Washington and Lake Union. There are dozens of such zones across the country, but this would be the first in the Pacific Northwest.

“We have such precious resources and sensitive areas along the Puget Sound that we believe a no discharge zone made a lot of sense,” Ecology Director Maia Bellon said at news conference at the Des Moines Marina.

Critics say the proposal is too broad and will be costly for many who must retrofit vessels to accommodate waste holding tanks. Many boat operators currently use marine sanitation devices that treat sewage before it is pumped overboard, they say.

“This important change will lead to water that is cleaner and food that is safer,” Secretary of Health John Wiesman said Thursday. People who swim in contaminated water or eat contaminated shellfish can get sick, he added.

The department says it sought the designation after four years of evaluation, outreach and public feedback. The EPA has 90 days to review the petition and make a decision.

A group representing numerous vessel operators, ports and shipyards say they’re concerned the department is moving ahead “without due regard for either the economic or scientific arguments against a Sound-wide” no discharge zone, the Puget Sound NDZ Marine Alliance wrote to Bellon in May. It also noted that use of onboard sanitation devices has never been linked to poor water quality.

Treated sewage discharges contain fecal bacteria concentrations that are many times higher than the state water quality standards, the agency said in its petition.

If approved, the sewage ban would apply to all vessels, which number more than 156,000 in Puget Sound. Tugboats, commercial fishing vessels and some others would have five years to comply.

Many boaters currently pump out toilet waste at stationary facilities, hold waste in tanks, or treat the waste before pumping it out. Currently, boaters are allowed to pump out treated sewage anywhere in Puget Sound. Federal law allows vessels to dump raw sewage only in waters more than 3 miles from the coast.

“It’s overkill. They’re picking the low fruit off the tree,” said Andy Paris, of Olympia, noting that boats represent a small share compared to the volumes of sewage that cities and others pump into waters.

He has a holding tank and a chemical treatment system on his 36-foot boat but worried about the costs for others.

Chris Wilke, executive director of the Puget Soundkeeper Alliance praised the move. “It’s time we looked at all pollution and stop treating Puget sound like our toilet,” he said.

The state estimates about 215 commercial boats and 2,000 recreational boats — or roughly 2 percent of vessels — would need to add holding tanks.

Retrofits for tug boats and commercial vessels could range from negligible to $161,000, according to a consultant for the department. The cost of adding a holding tank on a recreational boat is estimated to be about $1,500.

The agency said there are about 173 pump-out stations for recreational boaters, and another 15 commercial pump-outs. It is working with others to add more commercial pump-outs.