PARK RAPIDS, Minn. – About 2,000 people marched down a sun-soaked rural highway in western Minnesota on Monday as opposition to the half-built Enbridge Line 3 oil pipeline reached a fever pitch on a sweltering day.

"Defend the sacred, stop the pipeline," Indigenous activists and their allies chanted in waves as they approached a stretch of Mississippi River not far from the headwaters. "This is what treaty rights look like."

About 20 miles away, several hundred protesters disrupted construction at a pump station for the $3 billion pipeline that will carry 790,000 barrels of Canadian oil daily from Alberta to the Enbridge terminal in Superior, Wis. They locked themselves to equipment and blocked the access road with debris.

"We went to the meetings, and none of that helped," organizer Big Wind said as police arrested protesters and loaded them onto buses. "So here we are, taking direct action."

"We respect everyone's right to peacefully and lawfully protest," Enbridge spokeswoman Juli Kellner said in response to an e-mailed query about Monday's protests, "but trespass, intimidation, and destruction are unacceptable."

Enbridge has repeatedly said the controversial pipeline is needed to replace the 50-year-old deteriorating Line 3 and improve safety. It has gone through six years of regulatory review and has been approved by numerous agencies, including the Minnesota Pollution Control Agency, the Minnesota Department of Natural Resources and the U.S. Army Corps of Engineers.

"Many of the groups involved in the Treaty People Gathering were parties to the review process," Kellner said, "and during the past six years have repeatedly provided input that was heard and acted upon."

"We hoped all parties would come to accept the outcome of the thorough, science-based review and multiple approvals of the project."

Kellner said 44 employees were evacuated from the pump station site, and that the company's first priority is the safety of all involved, including the protesters. She called the damage done at the pump station "disheartening."

Dozens were arrested at the pump station, and at one point a Department of Homeland Security helicopter flew in low, blowing up dust in an apparent attempt to break up the occupation.

As the sun fell, the drumming continued and dozens of sheriff's deputies and police officers stood guarding the pump station, which looks similar to an electrical substation and keeps pressure in the pipeline.

'Just the beginning'

Prayers, songs and drums led marchers to one of the Mississippi River crossing points for the new pipeline as dragonflies swarmed overhead. Dozens dipped in the cool, shallow water while hundreds sang and gave speeches along the highway. It was the largest gathering to date along the 340-mile path of the pipeline in Minnesota.

Law enforcement kept their distance at the river march in Clearwater County even as protesters set up camp directly on the pipeline route, and some activists vowed on a boardwalk with tents and supplies they intended to stay "as long as possible" in order to halt construction on the pipeline.

"This is just the beginning," said Winona LaDuke, who heads the environmental and Indigenous group Honor the Earth.

The project faces several court challenges that could disrupt construction, and activists are pleading with Gov. Tim Walz and President Joe Biden to cancel key permits and pull the plug on Line 3 entirely.

"Our ancestors signed these treaties with your ancestors," said Nancy Beaulieu, an environmental organizer and member of the Leech Lake Band of Ojibwe.

Actress and activist Jane Fonda, making her second visit to a Line 3 protest in Minnesota, said Monday "we have to keep it up. We have to make it a major headache" to put pressure on Walz and Biden. Fonda was among the protesters who initially occupied the pump station Monday morning.

Pipeline opponents say Line 3 is a violation of treaty rights, puts sensitive areas at risk of oil spills and will exacerbate climate change.

"We ain't gonna quit until we kill the black snake," said Silas Neeland, a 13-year-old member of the White Earth Nation who rallied the crowd near the river numerous times.

Monday's turnout was a major escalation from earlier protests, which began as construction started in December and had resulted in about 250 total arrests before Monday. An influx of out-of-state water protectors, as protesters call themselves, helped boost numbers as the pipeline becomes a national battleground over climate change.

"Indigenous matriarchs have been praying for this moment, when allies and accomplices would join them on the front lines," Big Wind said. "And here it is."

Enbridge says that despite protests it is still on track to have the pipeline in service by the end of the year. Kellner said the project is already providing significant economic benefits for counties, small businesses, Native American communities and union members.

She added: "Protests to date, including today's Treaty People Gathering, have had relatively little impact on construction."