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… 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)... 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…

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… 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… 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… 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.