Ilesha, Nigeria - In his early twenties, Simeon Abolarinwa did the grown-up thing of making a curriculum vitae for the first time. At the bottom of the document, he listed his hobbies: hunting, hiking and fishing. Unlike many of his peers doing the same to fill space or boost their profiles, these were actually his hobbies.

Growing up in his native Osun state in southwest Nigeria, he regularly snuck out of the family house to make hooks out of binding wire and go fishing with friends in nearby streams.

These days, the 41 year old lives in Osogbo, the state capital, working as a network administrator with a university. His favourite place to fish is a spot on the Osun river, less than a kilometre (half a mile) from his apartment and a few kilometres from the Osun-Osogbo Sacred Grove, a UNESCO World Heritage site.

“I have this personal connection to Osun river,” Abolarinwa told Al Jazeera. “Where will I practise my hobby if not at the Osun river?”

He also goes to the grove - where fishing is not allowed - to play with monkeys and watch wildlife. During the lockdown, he took to going to his fishing spot to climb rocks or just sit and admire nature. “I have a lecturer friend at the university, an ornithologist who I’d go with to watch birds,” he said.

Sometimes he goes fishing alone and at other times, with a group of fishing enthusiasts. At times, they just admire their catch before releasing it back into the river but, mostly, they catch to eat.

On his Twitter profile, the pinned tweet is a photo of him excitedly grilling fish on an open fire, a new pastime for a man who disliked eating fresh fish as a child.

All this made Abolarinwa somewhat of a fishing nerd; he knows that elephant fish is too soft to be boiled but is best smoked, and that it is dangerous to fish during the rainy season because the water level rises.

He learned that October/November, the onset of the dry season, is fishing season because fish breed when the water level rises and “depending on the fish, within three months, they are sizeable to be caught”.

On a fishing trip just as the rainy season was ending in 2019, he found the water cloudy. He blamed it on flooding because the rain clouds things - unlike during the dry season when you can see the bottom of the river in the shallows.

“In the rainy season, that colour would be normal, as all the runoff comes into the water,” Abolarinwa told Al Jazeera. Dry season came, but the water stayed the same. Eventually, they began seeing dead fish floating on the water.

“We thought it was a temporary thing, that maybe someone threw chemicals into the tributary along the way, and the fish became dead and floated down,” he said. “[But] it became worse in 2020. The water was like tea, in the middle of the dry season.”

The fishermen Abolarinwa met - and farmers who were using the water for irrigation - wondered: Did someone poison the water? Why do we see so many dead fish?

What Abolarinwa’s friends didn’t know at the time was that two years prior, mining company Segilola Resources Operating Limited (SROL) had been bought by a Canadian company and had begun large-scale exploration in the Osun area.

Today, it runs the only large-scale commercial gold mine in Nigeria, even though the area has always been full of many artisanal miners.

Indeed, the story of Osun is as much about faith, migration and exploration as it is about the matrimony of elements that have long stayed single. From within and beyond Nigeria, many have come to the state because of their faith in what runs through the land or underneath it.

This August, thousands of people from across Nigeria and the Black diaspora, including Cuba, Brazil, and Trinidad and Tobago, visited the Osun-Osogbo grove for the annual two-week festival. As is the custom, many buy small kegs there to bottle the river’s water and take to their homes across the globe.

In Yoruba cosmology, Osun, goddess of love and sexuality, is one of several orisas or gods. In global pop culture, she is adored - and has been referenced by personalities like Dianne Reeves and Jennifer Lopez.

American singer Beyoncé identified as the goddess in her 2016 album Lemonade and the viral photoshoot announcing her pregnancy a year later, wearing the signature yellow-gold colour associated with Osun.

The part of the river that runs through the Osun grove, a natural habitat that has been preserved for 400 years, is believed to possess powers to give pregnancy and to heal generally. Mostly because of the efforts of Austrian-Nigerian artist Susanne Wenger, the grove was declared a national monument in 1965 and a UNESCO World Heritage site in 2005.

The river - which is named for the goddess and seen as her home - gives its name to Osun, one of Nigeria’s 36 states. Spanning 213km (132 miles), it flows across five states in southwest Nigeria, including Oyo, Ekiti, Ogun and Lagos where it enters the lagoon and pours into the Atlantic Ocean.

Across these states, its water is used for different purposes by people, including farmers. A couple of dams also cross it including one that feeds two major breweries in those states.

But Osun is also especially attractive because of its abundant mineral resources; from cassiterite, columbite and tourmaline to mica, marble and, the most valuable, gold.

For centuries, gods, gold and other minerals lived side by side peacefully.

In the 1970s, there was an oil boom that led to crude oil becoming the largest source of revenue for Nigeria. Before that, the government was involved in mining but in the years since, many sites were abandoned and mining became mostly the domain of artisanal miners.

In 1945, alluvial gold deposits were first discovered in the area known as the Iperindo Reef, 60km (37 miles) out of Osogbo. Small-scale mining started there and, by the 1980s, the erstwhile Nigerian Mining Corporation (NMC) set up the first industrial mining there. Later, Tropical Mines Limited (TML) acquired the project with the NMC retaining a 20 percent interest.

By 2007, when Nigerian authorities deregulated the sector, TML had birthed the Segilola Gold Project, operating in parts of Osun state including Iperindo. Within a decade, Thor Explorations Limited, a company listed on the Canadian Stock Exchange, got into the Segilola Gold Project through the acquisition of TML-backed SROL. That gave it control over mining lease ML41 (about 27sq km or 10.4 sq miles), exploration licence EL19066 and two other exploration licences across 30 communities in Ilesha.

The new owners, who started exploration in 2017, have, according to one of its representatives Ijeoma Ohaeri Koleso, “gone over and beyond regulatory requirements” in the mining process. It uses a tailings storage dam for its waste and said "frequent environmental compliance monitoring exercises are done by an accredited third party and witnessed by regulators."

Still, no one knows if the company followed due process during the exploration, an aide to Kayode Fayemi, who was minister of solid minerals at the time, told Al Jazeera on the condition of anonymity. Current ministry officials declined to comment on the matter.

At the time, mining was also being undertaken across the state by multiple artisanal miners and other small-scale miners.

Al Jazeera spoke to a number of employees of the National Museum, Osogbo - which houses the grove - but they refused to comment, insisting that Abuja had given instructions not to speak about the situation.

One told Al Jazeera anonymously that the authorities are afraid of the grove being delisted by UNESCO and that they expect the water to return to normal soon.

“In Osun, the contamination is through water which flows through communities with over two million people,” Anthony Adejuwon, head of Osogbo-based civic advocacy group Urban Alert, which had run tests on the Osun river, told Al Jazeera.

“If Bagega could record [hundreds of] deaths with a population of 7,000, imagine the number of children that will die in the next five years with a population of two million people. In our projection, the casualty figure between now and 2027 is around 100,000. In Bagega, it was just lead poisoning. Here, we have mercury, cyanide and lead.”

In 2011, an estimated 400 children died from lead poisoning in Bagega community in Zamfara state and thousands more were found to have excess levels of lead in their blood.

Urban Alert said its casualty projection extends to those who take water from the grove back home with them, to places as far-flung as the Caribbean and parts of South, Central and North America. It also said it asked for annual visitor logs for the grove but was told there is no data.

“Even those that did not come here physically are drinking the water. It is either they drink, or rub it on their head or their skin,” Adejuwon said.

Separate physiochemical tests on water samples from the area by Urban Alert and Al Jazeera revealed the presence of high levels of heavy metals.

In both tests, the water levels of arsenic and mercury - priority chemical contaminants according to the World Health Organization (WHO) and Nigerian Industrial Standards (NIS) - were 850 percent and more than 2,000 percent respectively above the permissible levels.

In Urban Alert’s tests for lead across four sites in Osun, results ranged from 1,000 percent (over the limit) at the grove to 2,000 percent at Ede, near another dam.

The Al Jazeera samples were taken near the Iperindo market, just about a kilometre (half a mile) away from Segilola's exploration area.

“Farmers use the water to feed vegetables, maize, etc.,” Adejuwon said. “There is something called foliar feeding in plants; it means a way of using leaves to absorb nutrients by plants. These plants absorb nutrients from the water that splashes on their leaves.”

“Just look into the future, can you imagine the amount of cyanide, lead and mercury that will be in each person’s system?” he said.

“Think about the fish caught inside the water; they dry it and sell it in the market, we all eat this fish. Even cattle come to the water to drink, do you know the implications?”

Another test by Al Jazeera confirmed discoloration of a water sample from the grove, due to excess levels of iron. “Water should be colourless, that’s the minimum requirement according to the UN recommended limit,” said Tosin Agunbiade, a Lagos-based health, safety and environment expert.

Nkem Torimiro, senior lecturer in microbiology at Obafemi Awolowo University, Ile-Ife, said people living along the Osun river - and their unborn children - are at risk of neurological disorders.

“Children exposed to high levels of lead could have behavioural disorders, learning disabilities and low IQ - which is irreversible,” she added.

“For arsenic, it’s a precursor for cancer,” she said, noting that effects will be long term, not immediate. “Approximately five years of exposure to arsenic can cause cancer. It’s associated with infant mortality and can cause a reduction in intelligence quotient in children. It also affects the fetus, especially when pregnant women are exposed to [pollution].”

No one knows for sure whose mining activity led to the river pollution.

Urban Alert ran a spatial analysis and found that the water runs clear from the river source in Igede-Ekiti, a community in the neighbouring Ekiti state, At Esa-Odo community in Osun where small-scale miners are operating, the clear water becomes brown.

There are two main types of mining: core and alluvial. In core mining, industrial equipment goes deep into the earth’s core while alluvial mining is mostly done by artisans and focuses on small deposits carried down a river.

“Gold deposit is like the heart - the blood pumps from the heart to the veins,” Urban Alert’s Adejuwon told Al Jazeera. “Alluvial is like the vein while the core is where [mines like] Segilola are working.”

In Nigeria, artisanal mining is more common. Artisans use light equipment like shovels and focus on alluvial deposits but others, backed by smaller companies, use heavier equipment, including excavators. In Osun, residents pointed out Chinese backers who operate under an atmosphere of secrecy and employ armed security operatives.

Across the course of the river and its tributaries, there are several mining sites.

Artisans rely on runoff water from the river, digging into the river bed and scattering water in all directions as they rinse off the mud to find gold, so the residue finds its way into the river. After exploration, the holes are left open, leading to pools infested with algae scattered across the southwest. Sometimes people fall into these holes, which can be very deep.

But experts say the sustained, large-scale pollution is not caused by artisans, who rely on hand tools and cannot afford the heavy-duty equipment of bigger players.

Mining remains controlled by the federal government as part of a constitutionally defined “exclusive list” of powers, even though it has deregulated the sector to allow state governments more control.

To get a commercial licence, approval must be obtained from federal authorities - the Mining Cadastre Office and the Ministry of Mines and Steel Development. Usually, the licence covers a large perimeter for exploration and a smaller one within it for mining.

In 2018, Omoniyi Temitope, Iperindo’s community liaison officer at the time, met with SROL as its representatives engaged three host communities to develop a Community Development Agreement (CDA) in tandem with the mining act of 2007.

In September 2021, Segilola heard that some artisanal miners had carved out a swath of land on its licensed mining and exploration areas in Iperindo, to mine gold.

A stone’s throw away from that site is a bustling market and a stream the community depends on for household chores. The stream is a tributary to the Opa river - which eventually empties into the Osun.

Temitope said the miners were community residents, some of whom were part of the CDA with Segilola. They had formed a new organisation in April 2021, with a different mission: small-scale mining. By September, the Iperindo Miner Artisanal Cooperative, as they called themselves, started working with illegal miners within Segilola’s licensed area.

"When they notified me, I told them that … mining on someone's ME or EL (mining licence or exploration licence) area is not acceptable, and the law doesn't permit that. They argued they would forcefully do it if I didn't support them," he said.

Segilola admitted there had been more than one incident of other parties prospecting within the area covered by its exploration licence. But its representatives repeatedly refused to give any details about them.

The company’s representatives showed Al Jazeera copies of letters written to the Ministry of Mines and Steel Development, Ministry of Environment, and state authorities reporting the artisanal activity and seeking to eject them using law enforcement.

"By law, we are required to report this to the Ministry of Mines and Steel,” a legal representative for Segilola told Al Jazeera.

“But we can't, as a company, say we are going there to stop it or do anything - by law, we are not permitted to do that. If you go to the ministry, there is a protocol. If the ministry should hear that you do otherwise, the hunter will become the hunted."

During Al Jazeera’s visit, miners were working on site, even in areas where the state-backed vigilante, the Joint Task Force (JTF), was policing.

Civil society groups say the company has focused on removing bigger entities encroaching on its site but has been slow to evacuate smaller-scale ones.

In May, two smaller companies, allegedly sponsoring illegal mining, showed up with an excavator to mine on a large scale. Segilola said it reported it to the state government and the machine was removed.

According to the Nigerian Senate, $9bn is lost annually to illegal mining and gold smuggling. Community members say elite patrons involved in the mining suffer no repercussions.

In September 2021, Nigeria’s junior minister of mines and steel, Uche Ogah - who has called for capital punishment for illegal mining - said at a Senate forum that perpetrators often conspire with security officers to mine illegally across Nigeria.

The Nigerian Minerals and Mining Regulation of 2011 specifies multiple fines for offenders, but “the problem is enforcement”, said Adejuwon.

In May 2020, the Osun government arrested 27 alleged illegal miners, more than half of whom were Chinese. Al Jazeera tried to reach a number of Chinese companies registered in the state for comment on their operations but there was no response.

In April 2021, Osun Governor Gboyeja Oyetola inaugurated a nine-member committee to tackle illegal mining in the state. Al Jazeera tried to reach one of them - Abimbola Oyediran, the federal mining officer and representative of the Federal Ministry of Mines and Steel Development in Osun state. But he did not respond to phone calls and text messages.

Last September, federal politicians also formed a committee to investigate illegal gold mining in Osun but so far nothing has come of it. This August, the National Environmental Standards and Regulations Enforcement Agency said it was investigating the pollution of the river.

For now, artisanal mining is still continuing, even near residential homes and markets across Osun. The presence of competing groups has reportedly led to the proliferation of firearms in some communities, according to residents of one town, Atorin-Ijesa.

In April 2019, artisanal mining was banned in Zamfara, as the authorities sought to curb banditry and other insecurity issues around the practice. Many artisanal miners began to emigrate towards the southwest to eke out a living at the artisanal mines.

One, a 38-year-old breadwinner for his two wives and eight children back in Gusau, the Zamfara capital, told Al Jazeera anonymously that he moved down soon after the ban. And then he made calls back home to male relatives and friends to join him, just as another friend had called him.

Ahead of this year’s Osun festival, the Ataoja of Osogbo - the town's traditional ruler - made efforts to get Osun worshippers to stop drinking the water. On March 30, an eight-point communique was issued after a stakeholder meeting at the grove, attended by the Ataoja’s representative, his olori (wife).

In June, a spokesman for the Osun government said the authorities were in discussion with an environmental consultant to clean up the river. Earlier this month, the National Environmental Standards and Regulations Enforcement Agency (NESRA) said it was investigating the matter.

But civil society groups like Urban Alert say the federal government and international community have to intervene, as with the Bagega episode, to prevent further complications for the culture and lives of the people living around the river.

Other experts say whatever the outcome, it is imperative to tackle the root cause of the pollution: illegal mining. “If you’re trying to clean up but the main source of these problems is still ongoing - then we’re wasting our time,” Torimiro said. “Mitigating now while the problem is still there is just like pouring water into baskets.”

One adherent of the Osun faith told Al Jazeera anonymously that she wished Wenger, who died in 2009, was still alive so her profile would have attracted international attention to the situation.

At the Osun-Osogbo festival this month, she and worshippers trooped out in their numbers, with yellow-and-gold attire and beads around their neck, wrists and ankles. They were hopeful for a miracle but still convinced of the river's enduring powers as they prayed and sang at the grove.

“Please help tell the government to stop the gold miners or find procedures that will not affect the colour of the water,” said Osunyemi Efunsola, who has been chief priestess of Busanyin, a companion deity for Osun, for the last 25 years. “People go to visit river Jordan in Jerusalem and fetch their sacred water and go to Mecca, too. This is our church and this is our mosque.”

“We have no other place to go,” the 72 year old told Al Jazeera while looking sorrowfully at the brown water running through the grove. “Osun is a mother so she is still lenient with them [perpetrators], but if she is ready, she can use a needle to fell an iroko tree. They should stop this action before they will regret the day they were born.”

It was Abolarinwa’s fishermen friends - both locals and some who migrated from northern Nigeria seeking opportunities in fishing and artisanal mining - who first told him that gold mining was responsible for the pollution.

Like the fish, they have since disappeared.

Other residents say 2019 was the last season people could fish in large numbers.

“They have not come back in like two years as there are no more fishes,” he told Al Jazeera. “We wouldn’t have come back again if not for the connection we have with the water.”

Abolarinwa said the first sign of how bad things were was when tilapia fish totally disappeared and only catfish, “the toughest ones” could be seen in the water. These days, he doesn’t take all his fishing rods to fish because he is unsure of any catch.

Sometimes, he even releases his bait back to the patch of soil where he found them, to let them live and die another day.