PORTLAND – Maine’s largest city is awaiting approval of a state discharge permit that could allow it to begin dumping truckloads of fresh snow from downtown streets into Portland Harbor by the end of the month.

While a handful of other coastal communities, including Rockland, have been dumping snow in the ocean for years, Portland hauls snow from congested downtown streets to locations several miles inland, where it piles up and forms a grimy glacier before melting by spring.

Because snow picks up pollutants while falling through the air or while covering streets and parking lots, ocean disposal raises environmental concerns.

“Wherever possible, keeping snow out of the bay and out of water bodies is a better remedy than dumping it in,” said Joseph Payne, Baykeeper for the Friends of Casco Bay.

But Portland’s plan has the backing of the state Department of Environmental Protection, which is accepting public comment on the city’s application for a permit and could issue one anytime after Dec. 22.

The plan’s overall benefits outweigh the risks, according to William Hinkel, environmental specialist with DEP’s Bureau of Land and Water Quality. He said conditions in the permit – such as only dumping snow within 72 hours of a storm – will limit the amount of pollution.

Hinkel also noted that dumping snow in the harbor means that the city won’t have to run a fleet of dump trucks on a 10-mile round-trip from downtown to an inland snow dump. “The environmental consequences of trucking all that stuff up there doesn’t make that a very [sensible] option,” he said.

Steve Hinchman, a lawyer with the Conservation Law Foundation in Brunswick, said it makes more sense to haul the snow inland and away from the bay because Portland Harbor already has toxic levels of pollution from storm water washing off city streets.

“Putting it directly in the water is the worst-case scenario,” he said. “Portland’s got to solve its storm water problems. This is the tip of the iceberg.”

Rockland has been routinely dumping truckloads of snow off its fish pier at least since the early 1990s, according to Public Works Director Gregory Blackwell, who said he was unaware of any damage or complaints arising from the dumping.

“You look at any snow bank and there’s going to be debris in it, but you try to minimize it,” he said. “The only problem we have is with the tides. Sometimes it’ll back up on us” if the tide is coming in.

Portland plans to use a giant snow blower to propel the snow into the harbor at the eastern end of the Ocean Gateway terminal, said city spokesman Peter DeWitt. The snow is expected to melt and disperse without causing mini icebergs in the shipping channel or interfering with navigation.