This post first appeared in Think Progress.

The 604-foot-long Hong Kong oil tanker Torm Aalborg is guided by the tugboat Andrew McAllister at right, through the gap under the Casco Bay Bridge on Sept. 22, 2008, in South Portland, Maine.

On Tuesday, approximately 25,000 residents of South Portland will decide the future of what could soon become America’s next tar sands pipeline. Not Keystone XL; the Portland-Montreal Pipeline.

In 1941, as Germany choked off Canada’s fuel supply during the early stages of World War II, the US opened a pipeline to allow imported crude to flow from Maine to Montreal. Today, that same pipeline has made Portland the second biggest oil port on the Eastern Seaboard. Tankers steam into Casco Bay almost daily, navigating among lobster buoys and kayakers and dwarfing the fishing boats that once lined the waterfront of Maine’s largest city.

But as natural gas has begun to replace heating oil in the Northeast and as Canada has moved aggressively to tap the Alberta tar sands, demand for imported oil is declining. And the pipeline’s owners and operators smell a new source of business: reversing the pipeline’s flow to send tar sands to Maine for export.

In June, nearly 4,000 South Portland residents responded to the threat that their hometown could serve as the next spigot for some of the dirtiest fuel on the planet by signing a petition to get a measure known as the Waterfront Protection Ordinance included on this year’s ballot, which would amend the city code to prevent the construction of a tar sands export facility at the end of the pipeline.

Larry Wilson, the pipeline company’s CEO, has repeatedly insisted that there are no current plans to use his infrastructure to move tar sands, but such a move is clearly at least on the drawing board. Wilson has repeatedly asserted that his organization is “aggressively looking for every opportunity — and that could involve a reversal” to ship tar sands south.

Towns along the pipeline’s route from Quebec, through Vermont and New Hampshire and down into Maine have already made official statements of opposition to the proposal. Vermont Governor Peter Shumlin wrote to Secretary of State John Kerry in June, asking him to block any move to ship tar sands through the pipeline.

Maine’s neighbors fear becoming the next Mayflower, Arkansas or Kalamazoo, Michigan. Both of those towns are still dealing with the aftermath of tar sands spills from pipelines that are wreaking havoc on public health and proving all but impossible to clean up. In the case of Kalamazoo, the process has lasted more than three years and cost over a billion dollars and the bottom of the Kalamazoo River remains choked with tar sands as thick as molasses.

However, resolutions by the pipeline’s pass-through communities are non-binding on the company. As the terminus and the municipality where oil would be stored, treated and loaded on tankers, South Portland is uniquely positioned to influence the company’s ability to move tar sands.

Local efforts have the pipeline company circling the wagons. Opponents of the Waterfront Protection Ordinance, united as the Working Waterfront Coalition, have outspent supporters six to one over the course of the campaign, spending $600,000 in cash and in-kind donations which have come exclusively from corporate entities and their affiliates, including the American Petroleum Institute.

Meanwhile organizations supporting the ordinance have spent just over $100,000, virtually all of which came from individual donations. Rob Sellin, who represents the group promoting the ordinance, said “one in every 100 South Portland voters has already supported our campaign financially and that number is growing every day. Their money is local from individuals who love and have a stake in the future of our community.” Supporters of the ordinance have made up for their financial shortfall with grassroots, volunteer canvassing, knocking on over 12,000 doors to spread their message.

The Working Waterfront Coalition has responded to the groundswell of opposition to tar sands shipment with attempts to portray the ordinance as a destructive tool that would force them to halt all current operations. To lend credence to their claims, they spent $15,000 on an economic analysis that found shutting down the city’s oil operations would result in the loss of 5,600 jobs and $252 million in earnings. One thing the study failed to mention is that nowhere in either the language or the intent of the ordinance is there anything to suggest current operations would have to be shut down.

Dave Owen, a professor at the University of Maine School of Law and a South Portland resident, pilloried the study’s assumptions, saying, “the report falsely assumed that the ordinance would close down all of the petroleum-related businesses, leading to collateral closures up and down the waterfront. That’s a fictitious assumption.”

One editor of the local weekly paper went a step further. He compared the Coalition’s tactics to the scene in “Blazing Saddles” in which Sheriff Bart attempts to bring the outlaws to heel by drawing his gun and putting it to his own temple, growling out a warning: “Hold it! The next man makes a move and the [sheriff] gets it!”

The [Waterfront Protection Ordinance] will do what its authors intend it to do: prevent diluted, sludge-like bitumen from being piped into the city from Canada, stored in tanks, processed to remove the harmful additives used to make it move through the pipeline and eventually loaded onto ocean-going tankers at the waterfront near Bug Light Park. What it will not do is gut the local economy or destroy the local oil industry. There’s nothing in the WPO that a court, reasonably intelligent city officials, or competent lawyers would ever misconstrue as forcing existing waterfront businesses of any kind out of existence.

In other words, the pro-pipeline coalition is threatening to take its own life if it doesn’t win the vote. But they’re the only ones holding a gun to their collective head.

The real risk to Portland’s waterfront jobs has nothing to do with jobs in the oil industry. The economic effect of a spill, additional air pollution, or even the perception of added pollution in Portland could have far-reaching effects on Portland’s much larger industries: fishing and tourism.

According to the coalition-funded report, oil operations at the port employ about 85 people who collectively earn about nine million dollars a year. By comparison, the National Ocean Economics Program found that in 2010, the ocean tourism and recreation industry in Cumberland County, which includes Portland and Casco Bay, accounted for over 12,000 jobs and and nearly $200 million in wages. And in 2012, Cumberland County’s lobstermen landed over $39 million worth of bottom-dwelling crustaceans which — as any chef worth his salt will tell you — go far better with butter or mayonnaise than they do with oil.

In 1996, the oil tanker Julie N hit the Casco Bay Bridge and spilled nearly 180,000 gallons of fuel and crude oils. The fallout from that accident cost the regional economy nearly half a billion dollars. Responders in Michigan and Arkansas have proven that there is no simple or effective way to clean up a tar sands spill and because it sinks in water rather than floating like other forms of crude, a leak of any kind could devastate the fishing and tourism industries in the Bay or Sebago Lake, which lies along the pipeline’s path and also serves as a source of much of southern Maine’s drinking water.

For those of us who live in South Portland, this vote represents a decision about the future of our city. The oil industry has been a part of the fabric of this community for decades. Massive holding tanks provide the backdrop to the high school football field, looming so close to the end zone it seems a kicker could hit one with a well struck field goal.

But that doesn’t mean we’re willing to allow those operations to expand or contribute to the distribution of one of the dirtiest fuels on the planet. South Portland Mayor Tom Blake has lived in the city all his life and spent 26 years as a firefighter and paramedic. He and his wife traveled to Mayflower, Arkansas this past spring to witness the after-effects of that town’s oil disaster.

“The similarities between Mayflower and South Portland are incredible. A 60 year-old pipeline owned by ExxonMobil, built to carry oil, but now carrying tar sands,” Blake said. “I feel certain this is not what we want for South Portland.”