Three communities in Papua New Guinea are waiting for the country’s Supreme Court to decide whether their concerns about the dumping of mine waste in the sea near their homes merit cancellation of an environmental permit for mining that the government issued in 2020.

U.S.-based Newmont Corporation and South Africa’s Harmony Gold Ltd., the partners in the development of the Wafi-Golpu copper and gold mine in Morobe province, want to pipe a slurry of leftover sediment, known as tailings, through a 103-kilometer (64-mile) pipeline. According to the companies’ plans, the tailings will travel from the mine through the pipeline until being discharged 200 meters (about 660 feet) under the sea at a point less than 1 km (0.6 mi) offshore in the Huon Gulf along PNG’s northern coastline.

The method is known as deep-sea tailings placement (DSTP), and in December 2020, PNG’s Conservation and Environmental Protection Authority (CEPA) approved the plan laid out in the companies’ environmental impact statement (EIS).

That approval triggered a series of legal battles beginning in 2021 that questioned whether Huon Gulf communities had been adequately informed of the risks of DSTP. Most recently, three leaders representing the villages of Labu Butu, Wagang and Yanga, located near the pipeline, sued CEPA’s leader and the government. Initially, the lawsuits aimed to stop the government from issuing a permit for large-scale mines called a “special mining lease” that would allow the project to move forward, citing the possibility of “catastrophic and irreplaceable damage to the marine environment and the eco-system of the Huon Gulf.” (In a separate 2021 case, a Supreme Court justice said the issuance of the environmental permit may have violated PNG’s 2002 Environment Act, based on evidence that communities weren’t apprised of these risks, and he temporarily suspended the permit.)

But, in November 2024, a national court judge ruled the villages weren’t in immediate danger and rejected their request to block the lease. Now, their hopes hinge on the Supreme Court ruling that the environmental permit isn’t valid because it didn’t adequately take into account the potential dangers of DSTP. The hearing had been scheduled for February 2025, but was delayed several times before happening on June 12. A decision is expected in July.

CEPA did not respond to Mongabay’s requests for comment.

For nearly a decade, a coalition of organizations has mounted a campaign to prevent the use of DSTP at the Wafi-Golpu mine. Over the mine’s anticipated 28-year life span, roughly 360 million metric tons of tailings and chemicals would be dumped in this part the Coral Triangle, a global hub of marine biodiversity, and the proposal has raised concerns about damages to the ecosystem. Opponents of DSTP say fisheries could also suffer, threatening the livelihoods of some 400,000 people in the region who depend on resources from the sea.

“The ocean is their only household economy. It’s like a garden to them. It’s their breakfast, lunch and dinner, and they’re not willing to give that up,” Jotham Keleino, a community leader from the Huon Gulf region, told Mongabay.

As of December 2024, seven mines currently dump waste into the sea worldwide, according to U.S.-based NGO Earthworks, which calls the practice of marine tailings disposal “outdated.” The operators of another five mines globally, including Wafi-Golpu, plan to use submarine disposal if they receive the required permits and financing.

Six of those existing or proposed mines are in PNG; none are located in South Africa, Australia or the U.S., where the companies that are, or were, involved in the Wafi-Golpu project are based. The dumping of waste into Australia’s waters, for example, is heavily regulated.

In public documents, the companies dispute the coalition’s claim that DSTP is illegal in Australia. They also say sites in Australia are generally less conducive to DSTP owing to a relatively shallow continental shelf that makes accessing the deep ocean difficult.

Still, their proposal to use DSTP in PNG strikes Keleino as “100% unfair.”

“We know that they have very strong environmental protection regulations,” Keleino said of the mining companies’ home countries. “That’s the billion-dollar question that boggles our mind. For goodness sake, how [do] you want to do that to my backyard here in Papua New Guinea?”

Communities also weren’t adequately informed of the risks of DSTP, he added.

In 2022, the coalition filed a human rights complaint with the Organisation for Economic Co-operation and Development (OECD), an intergovernmental policy forum. But at the same time, the companies, with apparent support from parts of the government, have continued to seek the special mining lease that would allow them to begin operations.

In March 2024, PNG’s mining minister identified completing the permitting process for the Wafi-Golpu mine as one of his key priorities. Less than a year later, a negotiator between the companies and the government told the news site RNZ he expected the mine to begin operating “within six to 12 months.” Morobe Governor Luther Wenge has also expressed his ongoingsupport for the mine.

PNG is also planning to help finance the project through state-owned Kumul Minerals Holdings Limited, in exchange for a stake in the mine, which negotiators say could amount to $15 billion in royalties for PNG.

Sarimu Kanu, Kumul’s managing director, called the Wafi-Golpu mine “the economy changer for PNG” in a video interview with the publication Business Advantage PNG. He also said Kumul would help with “smoothing” out “misunderstandings” between the companies and local landowners.

Kumul Minerals did not respond to requests for comment from Mongabay.

Dispute over impacts

The site of the proposed mine, which reportedly would be the largest underground mine in Papua New Guinea, sits about 65 km (40 mi) from Lae, PNG’s second-largest city. Newmont and Harmony say transporting the waste to the sea is less harmful to the people, environment and cultural heritage of the area than getting rid of it on land, and that tailings wouldn’t impact marine life in the gulf.

The companies, through the Wafi-Golpu Joint Venture, declined to comment on the court hearing because they are not a party to the case. A representative of the venture did not respond to other questions about the companies’ plans.

At a 2022 annual general meeting, Sandeep Biswas, then the CEO of Australia-based Newcrest Mining Limited (Harmony’s original partner on the project, which was acquired by Newmont in 2023), said the companies had determined DSTP would be the safest option after vetting 45 potential disposal sites. The EIS points out that the region is earthquake-prone and receives high rainfall, making land-based tailings disposal risky.

Biswas also said the Markham River already carries tens of millions of tons of silt from farther inland into the Huon Gulf every year that “is not dissimilar to the tailings” the mine would produce.

A video posted on Harmony Gold’s website citing the companies’ EIS suggests that the top 60 m (about 200 ft) of water in the Huon Gulf, where “most fish life” lives, won’t mix with the tailings expelled from the tailpipe at 200 m down. Instead, it says currents will carry most of the sediment — 60%, according to the EIS — down to eventually settle in the depths of Markham Canyon, 700 m (2,300 ft) below the surface.

Critics of DSTP point to byproducts and chemicals from mining, such as lead, manganese and mercury, that will tag along in the slurry emptied into the Huon Gulf. They note how little scientists know about the deep ocean and how sediment plumes might affect life there.

“The science hasn’t caught up,” said Ellen Moore, interim mining program co-director at Earthworks. What’s more, we know little about life in the deep sea, she added.

A 2015 study in the journal Scientific Reports on two other mines in PNG found that DSTP reduces the number of species living the sediments of the seafloor around the disposal site for Newmont’s Lihir gold mine compared to reference sites. Around the Misima gold mine’s disposal site, the researchers found evidence that DSTP affected the structure of sea life communities on the seabed more than three years after production had ceased in 2004.

A recent study published in Science Advances found that people have set eyes on less than 0.001% of the ocean depths — that is, below 200 m, which covers two-thirds of the planet. Research has continued to change the way we see the deep sea’s importance to sea life, our climate and even the air we breathe, the authors write.

An independent review of the EIS commissioned by CEPA, the government’s environment agency, found that the deep sea near the planned outflow is rich in biodiversity, and the results conclude that more of the sediment would end up suspended in the water column than the EIS reported. Still, CEPA issued an environmental permit allowing the mine to go forward in late 2020 — according to the coalition, in spite of those findings. The issuance helped prompt the communities’ legal action against the government in early 2021, in part, for failing to take the potential environmental damage into account.

In neighboring Madang province, the dumping of mine waste into the Bismarck Sea by the Ramu NiCo processing plant, which is linked to a nickel mine inland, made headlines in 2019 when a slurry spill stained coastal waters red. Before the spill, communities had been complaining about the impacts of the 5 million metric tons of waste released into the sea each year by Ramu NiCo for nearly two decades, and had filed several lawsuits against the majority owner. Still, the PNG government has yet to restrict the use of DSTP.

For leaders from the Huon Gulf region, their opposition is rooted in the swirl of potential dangers of DSTP, combined with what they describe as a lack of information. Now, they are asking that their voices be heard.

“Our issue is the deep-sea tailing dumping into the Huon Gulf is about to change our entire livelihood” as it has existed for generations, Keleino says. “That’s scary for us, and we need the government to stand up and show good leadership.”

Banner image: Jotham Keleino and his colleagues leave a community after training for the city of Lae. Image courtesy of Jotham Keleino.

John Cannon is a staff features writer with Mongabay. Find him on Bluesky and LinkedIn.

Citations:

Bell, K. L. C., Johannes, K. N., Kennedy, B. R. C., & Poulton, S. E. (2025). How little we’ve seen: A visual coverage estimate of the deep seafloor. Science Advances, 11(19), eadp8602. doi:10.1126/sciadv.adp8602

Hughes, D. J., Shimmield, T. M., Black, K. D., & Howe, J. A. (2015). Ecological impacts of large-scale disposal of mining waste in the deep sea. Scientific Reports, 5, 9985. doi:10.1038/srep09985

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