A new oil spill at a Shell facility in Nigeria has contaminated farmland and a river, upending livelihoods in the fishing and farming communities in part of the Niger Delta, which has long endured environmental pollution caused by the oil industry.

The National Oil Spill Detection and Response Agency, or NOSDRA, told The Associated Press that the spill came from the Trans-Niger Pipeline operated by Shell that crosses through communities in the Eleme area of Ogoniland, a region where the London-based energy giant has faced decadeslong local pushback to its oil exploration.

The volume of oil spilled has not been determined, but activists have published images of polluted farmland, water surfaces blighted by oil sheens and dead fish mired in sticky crude.

While spills are frequent in the region due to vandalism from oil thieves and a lack of maintenance to pipelines, according to the U.N. Environmental Program, activists call this a “major one.”

It is “one of the worst in the last 16 years in Ogoniland,” said Fyneface Dumnamene, an environmental activist whose nonproft monitors spills in the Delta region. It began June 11.

“It lasted for over a week, bursts into Okulu River — which adjoins other rivers and ultimately empties into the Atlantic Ocean — and affects several communities and displaces more than 300 fishers,” said Dumnamene of the Youths and Environmental Advocacy Centre.

He said tides have sent oil sheens about 10 kilometers (6 miles) further to creeks near the nation’s oil business capital, Port Harcourt.

Shell stopped production in Ogoniland more than 20 years ago amid deadly unrest from residents protesting environmental damage, but the Trans-Niger Pipeline still sends crude from oil fields in other areas through the region’s communities to export terminals.

The leak has been contained, but treating the fallout from the spill at farms and the Okulu River, which runs through communities, has stalled, NOSDRA Director General Idris Musa said.

Africa’s largest economy overwhelmingly depends on the Niger Delta’s oil resources for its earnings, but pollution from that production has denied residents access to clean water, hurt farming and fishing, and heightened the risk of violence, activists say.

The communities “are very angry because of the destruction of their livelihoods resulting from the obsoleteness of Shell’s equipment and are concerned the regulator and Shell will blame sabotage by the residents,” Dumnamene said.

At the request of the Nigerian government, the U.N. Environment Program conducted an independent environmental assessment of Ogoniland, releasing a report in 2011 that criticized Shell and the Nigerian government for 50 years of pollution and recommended a comprehensive, billion-dollar cleanup.

While, the government announced the cleanup in 2016, there is little evidence of restoration on the ground. The government says community protests and lawsuits by local activists have hampered progress.