Heavy machinery is used to cut trees to widen an existing Central Maine Power electricity corridor to make way for new utility poles, April 26, 2021, near Bingham, Maine. Credit: Robert F. Bukaty / AP

The pounding voters gave Central Maine Power Co.’s hydropower corridor in Tuesday’s referendum may not knock out the project, but it leaves deep uncertainty about how Maine and New England will meet ambitious clean-energy goals.

CMP continued work on the project the day after the rebuff by Maine voters, and the same day filed a lawsuit challenging the legality of the citizens’ initiative. On Thursday, a project opponent asked the state to halt construction. Legal experts expect a flurry of lawsuits to ensue as CMP tries to keep the $1 billion project on track and as large fossil-fuel companies with big profits at risk continue efforts to kill the corridor.

With the CMP corridor at risk or facing costly delays, Maine and Massachusetts need to quickly hone energy strategies. Gov. Janet Mills has set a goal of having 80 percent renewable energy by 2030 and 100 percent by 2050. Massachusetts, which is funding the corridor, has a goal of cutting greenhouse gas emissions by 45 percent below 1990 levels by 2030.

Experts predict that New England will need anywhere from two to four new electricity transmission lines in the next 30 years. Massachusetts is likely to let the fight around the corridor play out for a while, but it is likely considering alternatives. But they could also face problems. The referendum campaign provided a playbook for stalling new energy development.

“Any project like this is potentially extremely valuable to the region,” Jurgen Weiss, an energy economist and senior lecturer at Harvard Business School, said. “Maine benefits from a decarbonized energy supply.”

Weiss earlier worked with New Hampshire’s attorney general to tout that state’s Northern Pass transmission project, which failed to get a key permit and opened the door for CMP to win the Massachusetts contract. He said the public tends to be against large projects visible above ground.

Energy and legal experts speculated Friday about what roads are open to CMP and to Massachusetts outside of the legal cases. In Maine, CMP could move lines underground in a disputed public land section of the corridor or find an alternate route.

Another potential route that either CMP or another company might take is a proposal to connect Aroostook County to the regional grid approved by the Legislature this year. While the plan is not to design it for the electricity load of the CMP corridor, it could be adapted to be a conduit for that much power, experts said. However, that would require Hydro-Quebec moving its electricity route far east at high expense.

It is not clear how long Massachusetts will wait for the lawsuits surrounding the CMP corridor to be decided. The state is reviewing the outcome of the ballot initiative “and will be working with Avangrid and our regional partners on the path ahead to securing more affordable, renewable energy for Massachusetts,” Craig Gilvarg, spokesperson for the Energy and Environmental Affairs office, said.

Massachusetts likely is exploring its options as it waits for more clarity in Maine, Mark LeBel, an associate with the Regulatory Assistance Project, a group of former utility and environmental regulators who consult on energy issues, said. He added that other earlier bidders could potentially contact Massachusetts to express their renewed interest. But that likely would require a new request for proposals process.

Another option is a third proposed project in Vermont, which is permitted and would be built entirely underground. It is more expensive at an estimated $1.6 billion compared with $1 billion for the CMP project. The company running that project, TDI New England, did not respond to a request for comment on whether it has reached out to Massachusetts to indicate whether it is still interested. Each of the Maine, New Hampshire and Vermont projects proposed bringing Hydro-Quebec power via transmission lines.

After CMP rivals funded the successful referendum campaign, with NextEra Energy, which owns a nuclear station in New Hampshire and an oil-fired plant in Yarmouth, spending the most among them at $20 million in an alliance with environmentalists and grassroots groups, any new transmission line is likely to see political opposition.

“There are more questions than answers at this point,” LeBel said.

One thing that voters said clearly on Tuesday is that a better way to figure out how to decarbonize the economy is needed, said Jeff Marks, Maine director and senior policy advocate at the Acadia Center, which consulted on a benefits package for the CMP project. That will require massive planning.

“We need a better, more transparent way to do it that includes as many stakeholders in the process at the beginning as possible,” he said.