PORTLAND – Officials hope to have at least part of Portland Harbor declared a “no-discharge zone” by the federal government, which would bar the release of untreated water by any vessel.

“Gray water,” whether dishwater, shower water or any other water that is not sewage, can now be released.

“There’s a lot of concern about discharge from recreational and commercial vessels into Portland Harbor … Portland prohibits cruise ships tying up at its dock to discharge anything in the water, but that only represents about 40 ships, compared to 500 ships and thousands of pleasure craft that come into the Portland Harbor on an annual basis,” said Jeffrey Monroe, the city’s director of ports and transportation.

Federal law already bars the discharge of raw sewage within three miles of land, but because Maine’s coast has relatively few facilities for properly pumping out boats, it’s not an uncommon practice.

State law requires coastal marinas with more than 18 slips to have pump-out equipment. But the law has never been enforced, and fewer than 40 of the state’s approximately 300 marinas have waste disposal capacity.

If the harbor is designated a no-discharge zone, marinas will respond by installing pump-out facilities, Monroe predicted.