As Namibia’s arid heartland braces for another cycle of boom in gold mining, one question sits at the centre of environmental debate: where will all the water come from?
For Osino Resources, which is advancing the Twin Hills Gold Project near Karibib and Usakos, that question isn’t academic. It is existential. The company’s Environmental and Social Impact Assessment (ESIA) outlines a vision that must balance mining’s voracious water needs with the rights of local communities, the protection of fragile groundwater resources, and the ever-present risk of climate variability.
Twin Hills is no small venture. Osino’s feasibility studies estimate that it will require approximately 3,300 cubic metres of water per day, or around 1.1 million cubic metres annually, for processing, dust suppression, and support infrastructure once it is fully operational. In a country where average annual rainfall is among the lowest in sub-Saharan Africa, finding—and justifying—that volume is a significant challenge.
Tapping the Kranzberg Aquifer
The company’s ESIA, whose scoping report and Environmental Management Plan (EMP) were submitted for public review between 17 March and 14 April 2025, sets out its primary plan: tapping groundwater from on-site borefields and the larger Kranzberg Aquifer. Located near Usakos, the Kranzberg formation is a known regional aquifer that also serves farmers, towns, and other users in the Erongo region. Osino’s hydrogeological studies, which included extensive pump testing, suggest that the aquifer can sustainably yield approximately 460,800 cubic metres per year for the mine without threatening other users. However, this is based on cautious recharge estimates and conservative pumping plans.
To get this water to Twin Hills, Osino proposes a new pipeline from the Kranzberg borefields via Karibib to the mine site. The ESIA process for this water abstraction and transport system included public consultations, specialist hydrological modelling, and the development of a detailed Environmental Management Plan (EMP). This plan outlines obligations for continuous groundwater monitoring, adaptive management in the event of drawdowns exceeding thresholds, and clear mitigation steps in the event of aquifer stress.
Community concerns and consultation
Community feedback collected during the ESIA’s scoping phase focused sharply on this issue. Farmers, civic groups, and local authorities all flagged groundwater as a critical lifeline in an already water-stressed region. Osino’s consultants responded by building conservative pumping models and committing to share monitoring data transparently. The EMP includes triggers for modifying abstraction rates should monitoring reveal unintended impacts.
However, the company isn’t relying solely on a single aquifer. Recognising both the technical and social risks of relying entirely on the Kranzberg system, Osino’s ESIA outlines multiple contingency and diversification strategies designed to spread the burden and boost resilience.
Diversifying water sources
First among these is recycled process water. Twin Hills’ processing plant is being designed with a tailings filtration system to maximise water recovery, aiming for over 80% recycling of process water. The filtered tailings will be dry-stacked—a technology that uses far less water than conventional slurry tailings storage and reduces contamination risk.
Second, Osino is investigating the potential for treated municipal wastewater reuse, particularly from the Karibib sewage works. Upgrading this facility could provide a consistent supply of treated water for the mine while helping the town improve its sanitation infrastructure—a classic “win-win” scenario if managed effectively.
Third, the company is assessing options for managed aquifer recharge and surface water or sand storage systems, such as temporary dams in the Khan River. These measures would help store water during occasional flood events for gradual, managed use over time.
All of these diversification strategies reflect Osino’s acknowledgment that, in Namibia, water security can’t rely on a single source or a single plan.
Managing environmental risks
The ESIA is candid about the potential risks of such large-scale abstraction. Over-pumping could reduce groundwater levels, affect neighbouring boreholes, or damage dependent ecosystems. That’s why Osino’s consultants built mitigation commitments into the EMP: strict abstraction quotas aligned with sustainable yield estimates, regular groundwater level monitoring in both company and community boreholes, and adaptive pumping plans that can be dialled back if drawdown trends exceed safe limits.
Equally important is community consultation. The ESIA documents show that local stakeholders demanded detailed disclosure of pumping plans, monitoring results, and contingency measures. Osino pledged to establish ongoing communication forums to keep communities informed and involved in management decisions.
Balancing mining needs with local realities
Beyond Twin Hills, this ESIA provides a glimpse into the kind of planning that all mining in Namibia will require as water stress intensifies. Mining companies can no longer treat water as an unlimited input. Instead, they’ll face growing pressure—from regulators, communities, and investors alike—to show precisely how they’ll balance their own consumption with the needs of surrounding populations and ecosystems.
Osino’s approach, as laid out in the ESIA, is notable for recognising that balancing act. It proposes a combination of groundwater abstraction with sustainable yield limits, significant on-site recycling, and innovative reuse of treated wastewater. While no plan is risk-free, the layered strategy offers multiple lines of defence against over-extraction.
Of course, the proof will come in execution. Permits and modelling are only the start. Maintaining groundwater levels, building the pipeline responsibly, upgrading municipal wastewater treatment plants, and maintaining community trust will require ongoing attention and investment. Any slip in monitoring or transparency could erode the social license Osino is working to secure.
As Osino Resources pushes forward with its Twin Hills project, water will remain its most precious—and most scrutinised—resource.
The ESIA demonstrates that the company has conducted thorough research on sourcing, impact assessment, and stakeholder engagement. Now, the challenge is to turn plans on paper into real-world outcomes that keep both gold and water flowing—for the mine, and for everyone who calls this dry region home.
