SOUTH PORTLAND — The Boston law firm hired to help defend the city’s Clear Skies ordinance in federal court is charging discounted rates in what’s expected to be a high-profile lawsuit brought by oil and shipping businesses.

City officials hired Foley Hoag, a firm that specializes in environmental law, after the Portland Pipe Line Corp. filed suit against South Portland in February seeking to overturn the ordinance, which bans loading crude oil into tankers in Portland Harbor.

It’s unclear how long the lawsuit will take or how much it will cost, but Foley Hoag is charging discounted hourly rates of $250 to $650, depending on which staff member does the work, said City Manager Jim Gailey.

That represents a 10 percent discount from its regular rates, Gailey said. The firm also won’t charge for travel and overnight lodging related to meetings in Maine, at least until the start of any trial in the case.

City officials are grateful for the discount, Gailey said, especially as they try to raise donations for a Clear Skies Fund for what could be a long and expensive case.

“It’s greatly appreciated,” Gailey said. “We knew, bringing in a firm with strong environmental experience, that we’d be paying a higher price. The City Council for a number of months has thought that this could become a big case and they’re always concerned about costs.”

Approved last summer, the Clear Skies ordinance aims to prevent the pipeline company from reversing the flow of the South Portland-to-Montreal oil pipeline to bring Canadian oil – and potentially tar sands oil – into Maine.

Pipeline executives insisted throughout the ordinance review process that it had no contracts and no plans to reverse the flow of the pipeline. But significant changes in energy markets have led to steep declines in the volume of crude oil pumped through the pipeline, threatening its future viability.

LEGAL BATTLE STILL UNFUNDED

Gailey said his proposed budget for fiscal 2016, which starts July 1, doesn’t include money for the Clear Skies defense. He plans to discuss the potential cost with city councilors in coming weeks during budget review sessions.

“As time goes on, we’ll have a better understanding of the track that the case is on and the potential costs,” Gailey said. His 2016 budget request for other legal costs is $187,618, up from $184,917 in fiscal 2015.

Foley Hoag’s lawyers met with the City Council for the first time on Monday, in an executive session that included the city’s corporation counsel, Sally Daggett, a lawyer with Jensen Baird Gardner & Henry of Portland.

Jonathan Ettinger, lead counsel and a partner at Foley Hoag; and Jesse Alderman, an associate, briefed the council on their initial legal strategy, Gailey said. They told city officials they would charge for Ettinger’s time but not Alderman’s.

Foley Hoag declined a request for an interview with Ettinger or another staff member to discuss the case or their fees and expertise.

In its lawsuit, filed in U.S. District Court, the pipeline company alleges that the ordinance is unconstitutional because it interferes with interstate trade, discriminates against Canadian interests, devalues the pipeline and infringes on areas best left to the federal government.

The company is joined in challenging the ordinance by a trade association representing tug, towboat and barge operators.

The city’s lawyers plan to file a response by the deadline on Tuesday, Gailey said.

The Clear Skies ordinance was adopted in July, eight months after South Portland voters rejected a proposal that would have allowed only the unloading of oil in South Portland.

Supporters of the ban said reversing the pipeline could increase the risk of spills and would require the construction of smokestacks next to Bug Light Park to burn off gases associated with loading diluted bitumen – otherwise known as tar sands oil – from the pipeline onto tankers.

Opponents of the ban said those concerns were unfounded and worried that the ban would hurt an important employer and taxpayer in the city.

The city set up the Clear Signs Fund after its general liability insurance carrier, the Maine Municipal Association, said its policy doesn’t cover the pipeline lawsuit.

So far, fund has received $3,200 in donations, according to city records.

All of the money has come from individuals, most of them South Portland residents.

Some donations have come from residents of nearby communities, including Jeff Dunlop, a retiree in Windham who sent a check for $100.

Dunlop said he lives about 400 feet from the pipeline, but his concern is regional. He’s especially worried because the pipeline runs through the Sebago Lake watershed, which provides water to Greater Portland.

“Reversing that pipeline would be the worst thing for this area,” Dunlop said. “It’s an environmental disaster waiting to happen.”