Dozens of committed activists and other opponents of the $1.2 billion expansion of Interstate 70 through northeast Denver lost a big challenge against the project last week, but don’t count them out — not yet.

One attorney for an environmental law firm speculated that federal officials’ findings in favor of the Colorado Department of Transportation on a civil rights complaint — one lodged on behalf of the heavily Latino neighborhoods of Elyria-Swansea and Globeville — would only embolden critics fighting the highway in other ways.

And there still are several avenues open: Pending and expected lawsuits are taking direct aim at the project and, if successful, could delay or even scuttle it. Other efforts are focused on mobilizing more opposition to ratchet up political pressure at the state and local levels. An opportunity may lie in a sales-tax ballot measure now under consideration by lawmakers that would raise $3.5 billion for other state transportation projects.

Should that measure make it on the November ballot, several involved in the opposition say to expect to see “Ditch the Ditch” anti-I-70 activists use the ballot campaign as a platform for their cause.

While CDOT questions the extent of the project’s opposition, it has roared back at times in recent months — most notably at a fiery community meeting in mid-February.

“What they’re seeing right now is a very organized opposition that’s somehow been able to find resources and people power to do the work that needs to be done in the community,” said Candi CdeBaca, a community organizer and founder of the revived Cross Community Coalition in Elyria-Swansea.

CDOT’s plans in the funded first phase of the project call for widening of the six-lane freeway between Brighton Boulevard and Chambers Road; that would accommodate a new, managed express toll lane in each direction. Through Elyria-Swansea, where an existing but decaying viaduct bisected the community 53 years ago, the 1.8-mile span would be replaced by a below-grade highway between Brighton Boulevard and Colorado Boulevard, with a 4-acre parkland cap planned atop part of it as one of many concessions by CDOT.

Still, between the new lanes and frontage roads, I-70’s footprint would be tripled. The project’s heft has spurred calls for CDOT to rip out I-70 entirely and reroute the traffic along interstates 270 and 76 to the north, an option CDOT has heartily rejected as unrealistic.

But stopping the project could prove difficult.

CDOT in January finished navigating a labyrinthine environmental impact review process and received a federal green light for the I-70 project, in the form of a “Record of Decision” issued by the Federal Highway Administration.

“It’s awfully hard at this stage of the game” to stop a big project, said Robert Yaro, a professor of city and regional planning at the University of Pennsylvania. He’s also a former president of the Regional Plan Association, which has helped marshal giant public works projects in New York, New Jersey and Connecticut.

“But if you find a sympathetic judge,” Yaro added, “then anything can happen.”

CDOT executive Shailen Bhatt, both in interviews and while facing the angry crowd in February, has expressed confidence CDOT will break ground on the five-year project early next year. But he acknowledges that another round of lawsuits is all but inevitable.

Here is a look at what the project’s hurdles may look like in coming months, according to several opponents interviewed by The Denver Post.

New legal challenges likely

The project has attracted one direct lawsuit and another that’s indirectly related, while two more are brewing:

The Sierra Club’s Rocky Mountain chapter a year ago filed a lawsuit against the Environmental Protection Agency. It challenges a change in federal air-quality standards that allowed for the I-70 project to move forward (the older standard likely wouldn’t). The lawsuit’s success could be a fatal blow to the project, Sierra Club lawyer Bob Yuhnke said. The U.S. Court of Appeals for the District of Columbia hasn’t yet scheduled arguments.

Also last year, former Colorado Attorney General J.D. MacFarlane filed a lawsuit challenging the city’s plan to use part of City Park Golf Course for stormwater detention . That project is part of the wider Platte to Park Hill storm-drainage plan that would help protect the lowered section of I-70, but city officials say they would pursue those stormwater projects anyway.

That project is part of the wider Platte to Park Hill storm-drainage plan that would help protect the lowered section of I-70, but city officials say they would pursue those stormwater projects anyway. Yuhnke confirmed that the Sierra Club is considering a second air-quality lawsuit challenging CDOT’s recently updated air-quality impact projections for the I-70 project.

CdeBaca’s group is among several neighborhood organizations hoping to press a legal challenge of the Record of Decision in a united front. It’s possible other opponents could mount separate challenges of the environmental impact review process.

The date to watch is July 10, Yuhnke said, since that will mark the deadline for any legal challenge to be filed against the I-70 project. That is based on federal rules that set the cut-off at 150 days after the publication of the Record of Decision in the Federal Register.

“I think that the Clean Air Act challenges … have the most power to just stop the project in its tracks,” CdeBaca said. But a separate challenge of the Record of Decision, if successful, might only slow down the project, she said.

Passionate opponents hope to recruit allies

Just before CDOT’s Feb. 16 community meeting, Bhatt wrote in a department Facebook post that “a small group of about 60-70 people” was still pushing for a rerouting alternative. But if that’s the case, every member of that small group attended the meeting — and brought their friends to press Bhatt with heated questions and frequent interruptions.

“I think today’s decision will really inspire the community to redouble its efforts and seek justice,” Earthjustice attorney Joel Minor told The Post on Thursday after the Federal Highway Administration found in CDOT’s favor in the civil rights investigation.

The lawsuits aim to delay the project, halt it altogether — or force more community concessions by CDOT, as City Council members including Debbie Ortega and Albus Brooks are urging. CDOT has already agreed to measures that include the highway cover and providing air conditioner units and interior storm windows to nearby residents to help keep out construction dust and noise. It’s also paying for several changes to Swansea Elementary School, next to the viaduct.

But CdeBaca and others say they will try to ratchet up the pressure on elected officials who support the project, from Mayor Michael Hancock to state legislators and Gov. John Hickenlooper.

That could allow them to capitalize on any delays. If they’re successful in building broader opposition — an open question — their best bet could be to make I-70 an issue in the 2018 governor’s race to replace Hickenlooper.

Already, the Elyria-Swansea activists and reroute supporters who live in other parts of the metro area have found common cause with City Park activists fighting the drainage projects. That combination has drowned out project supporters — prompting officials, including Hancock, to argue that many in northeast Denver support the project but are reluctant to speak up.

But first, there is the potential November transportation funding ballot measure.

Steve Kinney of Unite North Metro Denver, which has pushed to reroute the highway, said that may give opponents a platform to say: “Until CDOT is demonstrating that they are spending our money wisely, then CDOT should get no additional money.”

Where the I-70 project stands

Until a court tells them otherwise, CDOT officials are pushing ahead. Four teams vying for a public-private partnership are working on final project proposals, with the technical aspects due in June and a financial bid due in August, said project spokeswoman Rebecca White.

The funding — including $850 million in anticipated fees collected to help fix the state’s roads and bridges — appears to be solid, so long as CDOT’s $1.17 billion construction estimate is borne out in the contractors’ proposals. White said CDOT anticipates negotiating set costs to pay for the project, placing the risk of overruns on the private partner.

“We as a department are moving forward,” Bhatt said during the February meeting, in between protests from attendees. “We are in a legal process now … (and) a court will decide if we have followed the law.”