In November 2022, a major accident occurred at the Williamson diamond mine in Tanzania’s Shinyanga region, when approximately 150 meters of the eastern wall of the mine’s tailings storage facility (TSF) collapsed. This released a large volume of tailings slurry that spread northeast, covering an estimated 5.4 km² in a single day and severely impacting land and water resources in and around the mine concession.
Satellite imagery shows that while most of the slurry remained within the mine’s boundaries, approximately 1.52 km² of land outside the concession was also flooded, affecting the nearby villages of Nyenze and Ng’wangh’olo. No major injuries or fatalities were reported, but the material damage was severe — impacting land, property, water access and livelihoods. Many households suffered losses of income-generating activities, land, property, crops, and food reserves, deepening pre-existing vulnerabilities.
Over the past 2.5 years, IPIS interviewed 34 local residents about the accident, its long-term impacts and the remediation efforts undertaken by the mining company (Williamson Diamonds Limited or WDL). This briefing analyses these perspectives, assessing whether restoration efforts met community needs and how these responses have shaped trust between the mine and the communities affected by the tailings dam collapse.
First investigations into the tailings dam failure
Tailings storage facilities are designed to safely contain mining waste and process water. Although international standards—such as the Global Industry Standard on Tailings Management (GISTM)—outline best practices for tailings storage, these are not consistently reflected in national legislation or adequately enforced, making tailings accidents quite common, often with far-reaching impacts on communities and environments.
Just days after the accident, the Minister for Minerals visited the area, assuring that the mining company would provide immediate food assistance and transportation support for school-going children, as well as proper compensation for all those affected. A regional emergency committee, composed of government representatives and company staff coordinated the response, with WDL providing humanitarian assistance and shelter to those affected. The National Environmental Management Council (NEMC) equally responded swiftly and deployed a team of experts to assess the impacts and liabilities of the tailings dam breach. It fined WDL TZS 1 billion (circa € 326,000) for shortcomings in emergency preparedness and facility construction. Prompt water tests by the Government Chemist Laboratory Authority confirmed that no hazardous chemicals had been released into the environment.
In their initial analyses, Tanzanian authorities, independent experts and academics all suggested that adherence to best practice tailings management standards and monitoring could have prevented the breach at the Williamson mine. Petra Diamonds – the mine’s majority owner at the time, that has since relinquished its shares to the Tanzanian-owned Pink Diamonds – communicated in-depth internal investigations into the cause of the accident, with a public report seemingly still pending to date.
Following the breach, mining operations were suspended for over eight months, resuming in July 2023 with government approval. A new TSF was constructed compliant with the GISTM standards.
Impact on livelihoods
The livelihoods of villagers in Nyenze and Ng’wangh’olo were severely affected. One resident recalled:
“I was at a funeral when it happened. I rushed back and was able to rescue some of my livestock, but seven cows got buried in mud”.
Many households and farms suffered damage. 286 individuals from 50 houses had to be relocated, while at least 23 houses were either completely destroyed or deemed uninhabitable. Livestock was lost, pastures compromised, and crops and rice fields damaged, seriously affecting food supplies and income.
Access to (clean) water became a key concern. With tailings-rich mud contaminating rivers and shallow wells, and the area’s most important freshwater reservoir (the Alamasi water dam) inaccessible, local economic activities such as agriculture, livestock keeping and artisanal diamond mining suffered, and water for domestic use became scarce.
Addressing critical water needs
WDL trucked water to affected villages for over a year, until February 2024. While providing much-needed relief, residents voiced concerns about the unpredictability and insufficiency of supply. With no fixed schedule, many villagers made multiple trips each day in the hope of catching the truck—and if they missed it, they had to wait another day or more.
In July 2023, WDL completed the Ng’wangh’olo water dam to replace the flooded Alamasi reservoir. However, many residents expressed dissatisfaction, noting that it is significantly smaller than the original and insufficient for community needs. In April 2024, the ongoing scarcity led some villagers to illegally tap the water pipeline connecting Lake Victoria to Maswa district in Simiyu region. Authorities later repaired the pipeline and installed a collection point in Nyenze.
Resettlement
For those whose houses were severely damaged, WDL offered either relocation to a new home or cash compensation to rebuild independently. Several residents said the cash option was discouraged, and those who chose it reportedly received a flat payment of TZS 5 million (around € 1,930 at mid-2023 rates), which many considered insufficient.
Most replacement houses were built within the original village, allowing residents to remain in familiar surroundings. The new houses were of more durable construction, but dissatisfaction arose over the lack of community input on location, size, and cultural considerations. Many homes were smaller than the original mud dwellings, making them unsuitable for larger families. As one resident explained: “I got one small house of 7x6m, with three small rooms and a small sitting room. I have a family of eight people and cannot even put in my sofa set.” Due to limited space, some households use kitchen units as bedrooms, while others have abandoned the buildings altogether for self-built mud houses, often repurposing replacement houses for storage.
The Parliamentary Committee on Mining, which visited the affected communities in February 2024, commended WDL for providing social services and compensation, but advised to review the compensation process to better empower communities and address remaining grievances.
Compensation for damages
Following the identification of affected individuals and the valuation of damages by a government valuer, Petra Diamonds reported in July 2023 that “303 out of 304 affected persons [had] been appropriately compensated in line with Tanzanian regulations and International Finance Corporation (IFC) best practice.” Compensation was carried out in two phases: a first phase in April 2023 covered property losses for 294 individuals (totaling TZS 1.8 billion/ € 700,000), and the second phase in June 2023 addressed losses of crops, trees, business income, and disturbance allowances.
While comprehensive, many residents expressed confusion over compensation calculations and what specific losses were covered. Overall, residents felt their participation in the valuation and compensation decision process was very limited. Crucial information did not reach them sufficiently, and left them wondering about the fairness of the process. Most affected residents we spoke to felt that the compensation did not fully address broader social and livelihood impacts, including the longer-term impact of the access to land they lost.
To date, farmers continue to struggle to find suitable grazing land, as affected areas have become overgrown with wetland vegetation. Additionally, local residents who traditionally cultivated vegetable gardens along the seasonal Tungu River claim they have not been compensated, as this activity is condoned but not formally allowed.
Artisanal diamond miners faced particular challenges. While some reported receiving compensation for lost or damaged equipment, most felt that the broader impacts on their livelihoods were entirely overlooked. The destruction of key water sources—vital to their mining activities—forced many to cease operations altogether. Working informally, these miners were unable to substantiate their claims and were left to cope on their own.
Amid these often-serious grievances, many residents expressed uncertainty about how to raise complaints or seek redress. In correspondence with IPIS, Petra Diamonds indicated that a “community grievance mechanism dedicated to the tailings dam incident” had been established at the Williamson mine. However, no interviewed residents were aware of it, raising concerns about its visibility and accessibility.
Confusion over land ownership following compensation
An emerging concern involves access to land for which households received compensation. Affected residents understood that compensation was intended solely for damages, but many now report being prohibited from returning to their land, even where only a portion of it was damaged by the tailings mud.
As one resident explained, “The authorities have stopped us from using our damaged land, insisting that the land now belongs to Williamson since we were compensated.” Another shared, “After some time, some of my kids went back and stayed in the part of the remaining house that wasn’t completely damaged, but they were chased away.” A resident who was compensated for the 4 out of 26ha of his land that were flooded asked “I wonder how to get back the 22ha of my land that were not flooded”.
During its visits, IPIS found much of the affected land still covered in tick tailings mud, with areas demarcated by warning signs stating “Mud pond: deep”. No locals interviewed were aware of announced soil rehabilitation efforts. While safety may be a factor for not allowing people to return, the lack of clear communication causes confusion, raising broader concerns about the transparency of the compensation process and the risk of involuntary displacement without proper process or legal clarity.
Role of local government authorities
In a context where land ownership is governed by customary practices, with no comprehensive land registry and often no formal titles, valuers and mine staff relied heavily on village authorities to identify affected individuals. This dependence on local leaders as intermediaries gave them significant influence, leading to allegations of favoritism, corruption, and abuse of power. Some residents alleged that compensation was biased in favor of those close to village leaders, while others with similar claims—particularly those not on good terms with the local leadership—received less, and in some cases even were excluded from the process altogether.
Further grievances centered on the apparent focus on compensating less permanent mud housing, while damage to more durable structures was allegedly re-evaluated and no longer considered for compensation on the grounds that it would not compromise living safety. Some villagers therefore alleged that local authorities prioritized the mine’s interests over those of the community. These issues further eroded trust in the compensation process, amplifying perceptions of unfairness and marginalization.
Restoration and remediation in a context of fragile trust
The tailings dam breach at Williamson mine had immediate and lasting impacts on the communities of Nyenze and Ng’wangh’olo — damaging land, livelihoods, water sources, and community trust. It exposed shortcomings in corporate responsibility, community engagement, compensation practices, and regulatory oversight. Despite various forms of support, many affected residents felt excluded, undercompensated, or inadequately informed, deepening the social divide between the mining company and local communities.
The context and timing of the accident is critical to understanding the broader importance of the dam breach’s management. The accident occurred a year and a half after Petra Diamonds settled a London court case over serious human rights abuses by its former private security contractor, and just as it began implementing a restorative justice process. Restoration and remediation of the tailings dam failure, with its perceived shortcomings, happened in a context of fragile trust, and further strained already fragile relations between the communities and the mining company.
Beyond restoration and remediation, restoring trust demands open, inclusive dialogue, which many residents felt was lacking. Moving forward, the Williamson mine should prioritize tailings safety through regular inspections and modern monitoring, while engaging communities transparently in decision-making. Addressing unresolved concerns around land, water, and compensation is essential not only for recovery, but for rebuilding trust and preventing future harm.
FURTHER READING
This briefing was produced with the financial assistance of the European Union. The contents of the editorial is the sole responsibility of IPIS and can under no circumstances be regarded as reflecting the position of the European Union.
