Mining in Rwanda

Lessons

Senior 4 · Geography

Mining in Rwanda

4 lessons

Lesson 4 of 4

Mining Problems, Environmental Effects and Their Mitigation

25 min

Water samples above and below the mine

From 7 to 11 September 2026 the Rwanda Water Resources Board (RWB) investigated mining concessions in Kamonyi District. Its officers checked drainage, sediment control, wastewater and mine waste, and sampled the water upstream and downstream for pH, total suspended solids (TSS), turbidity, electrical conductivity and dissolved solids (RWB, 2026). Why compare upstream with downstream? Because the difference shows what the mine adds to the river.

Figure 5. Mining activities, their effects and ways to reduce them. Drawn by Ganzaa from REMA (2021), RWB (2026) and MINEMA (2025).

Definition

Environmental impact assessment (EIA): a study, made before a project is approved, of its likely effects on the environment and of how to reduce them. Strategic environmental assessment (SEA): the same kind of study applied to a whole policy or plan.

Total suspended solids (TSS): the mass of particles carried in a litre of water, in mg/L. Siltation: the settling of eroded sediment in rivers, wetlands and reservoirs. Rehabilitation: restoring mined land to a safe, productive use.

Problems facing mining

Problem	Evidence	Solution
Price swings	Earnings fell 29.6% in 2021; in 2024–25 unit prices fell (NISR, 2025; MINICOM, 2025)	Diversify minerals (lithium, rare earths); add value at home
Limited exploration and data	Lack of updated data on mineral resources (REMA, 2021)	State exploration data and blocks offered to investors (RMB, 2025)
Little finance, old technology, few skills	Named as key constraints (REMA, 2021); miners say banks will not lend to them (RBA, 2020)	Investment promotion, mechanisation, training, consolidating small mines into larger blocks
Illegal mining and trading	A key constraint (REMA, 2021)	Licensing, tagging, inspections
Accidents	14 mine disasters killed 20 people and injured 16 in 2025 (MINEMA, 2025)	Mining safety standards (2017), inspection, safe tunnel supports
Conflict with farming and settlement	Mines, pits and waste occupy hillsides and valleys that farmers need	Land-use planning, compensation, rehabilitation for farming

Environmental effects and their mitigation

Muddy rivers. Waters draining the mining areas of Rutongo and Gatumba carried clay and sand into the Nyabarongo and Nyabugogo (REMA, 2009). Mining releases sediment-loaded processing water and keeps eroding disturbed land and waste (REMA, 2021). In 2012 mining in the Western Province was suspended because it endangered the River Sebeya (Wikipedia, "Mining industry of Rwanda").
Land degradation: pits, trenches, tailings dams and the removal of soil and vegetation (REMA, 2021).
Pollution: dust and metals such as lead, cadmium, zinc and copper in air and water, making soil toxic (REMA, 2021).
Deforestation and loss of biodiversity, from clearing land and using wood for tunnel props and drying.

Mitigation combines rules and practice. Rules: EIA guidelines for mining projects (2012), environmental audit guidelines (2014) and mining safety standards (2017) (REMA, 2021); a strategic environmental assessment of the 2017 Mining and Minerals Policy; RWB inspections and water permits. Practice: settling ponds and water reuse, drains and sediment traps, buffer zones along rivers, containing waste, back-filling and replanting worked-out pits.

Worked example 1: how much sediment does a mine add?

Illustrative data. A stream below a washing site carries 460 mg/L of suspended solids; above the site it carries 40 mg/L. The discharge is $2.0\ \text{m}^3\,\text{s}^{-1}$ . (1 mg/L = 1 g/m³.)

\text{extra TSS} = 460 - 40 = 420\ \text{mg/L} = 420\ \text{g/m}^3 = 0.42\ \text{kg/m}^3

\text{extra load} = 0.42 \times 2.0 = 0.84\ \text{kg/s} \qquad 0.84 \times 86\,400 = 72\,576\ \text{kg} \approx 72.6\ \text{t a day}

Interpretation. Downstream water carries 11.5 times as much sediment, adding more than 70 tonnes a day to the river: enough to silt wetlands and reservoirs and smother fish spawning beds. This is why RWB samples above and below mines and why settling ponds are required.

Worked example 2: how dangerous are mine disasters?

Data (MINEMA, 2025), for 2025. All disasters: 1,269 incidents and 145 deaths. Mine disasters: 14 incidents, 20 deaths. Lightning: 200 incidents, 87 deaths.

\text{share of deaths} = \frac{20}{145} \times 100 = 13.8\%

\text{deaths per incident: mines } \frac{20}{14} = 1.43 \qquad \text{lightning } \frac{87}{200} = 0.44

Interpretation. Mine disasters are rare (about 1% of incidents) but the most deadly per incident, over three times as deadly as a lightning strike. Collapses of unsupported pits and tunnels are the main danger, which is why safety standards and mechanised, engineered mines matter.

Warning

Name the evidence and the place. "Mining causes pollution" earns little credit. Write, for example: "Washing ore at Rutongo and Gatumba sent clay and sand into the Nyabarongo and Nyabugogo (REMA, 2009); settling ponds and buffer zones reduce this."

RMB: "Mining companies commended for implementing Strategic Environment Assessment". In September 2019 UNDP, the Ministry of Environment, REMA and RMB visited two mining companies in Rwamagana District. Note the environmental measures you see on the sites.

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Practice

Give five problems facing mining in Rwanda, with a solution for each.
Explain how ore washing pollutes rivers, using a Rwandan example.
Upstream TSS is 25 mg/L and downstream TSS is 325 mg/L at a discharge of 1.5 m³ s⁻¹. Calculate the extra sediment load in kg/s and in tonnes per day.
Distinguish an EIA from an SEA.
In 2025, what percentage of mine-disaster casualties (deaths and injuries) were deaths?
Suggest how a worked-out pit could be rehabilitated.
"The environmental costs of mining in Rwanda outweigh its benefits." Evaluate.

Show answersHide answers

Price swings (diversify, add value); poor data (exploration); little finance and old technology (investment, mechanisation, training); illegal mining (licensing, tagging, inspection); accidents (safety standards, supports); land conflict (planning, rehabilitation).
Water used to wash ore picks up clay and sand and flows into streams, raising turbidity and silting downstream channels and wetlands: e.g. Rutongo and Gatumba into the Nyabarongo and Nyabugogo (REMA, 2009).
Extra TSS $= 300\ \text{mg/L} = 0.30\ \text{kg/m}^3$ ; load $= 0.30 \times 1.5 = 0.45\ \text{kg/s}$ ; $0.45 \times 86\,400 = 38\,880\ \text{kg} \approx 38.9\ \text{t a day}$ .
An EIA assesses one project before approval; an SEA assesses a whole policy or plan, such as the 2017 Mining and Minerals Policy.
$\frac{20}{20 + 16} \times 100 = 55.6\%$ .
Back-fill with waste rock, replace topsoil, terrace and replant (trees, grass or crops), fence remaining hazards; or convert to a pond for fish or irrigation if safe.
Costs: muddy rivers and siltation, land degradation, metals, deforestation, 20 deaths in 2025. Benefits: US$1,755 million of exports (2024), 85,498 jobs, materials for building. Most costs can be reduced by enforced rules (EIA, settling ponds, rehabilitation, safety). Judgement: benefits outweigh costs only where mitigation is enforced; RWB and RMB inspections are the test.

Quick check

Why does RWB sample water both upstream and downstream of a mine?

Key points

Problems: price swings, poor data, little finance, old technology, few skills, illegal mining, accidents (20 deaths in 14 mine disasters, 2025), land conflict.
Environmental effects: sediment and turbidity in rivers (Rutongo, Gatumba; Sebeya 2012), land degradation, dust and metals, deforestation and biodiversity loss.
Mitigation: EIA (2012), audits (2014), safety standards (2017), SEA of the 2017 policy, RWB monitoring (Kamonyi, September 2026); settling ponds, buffer zones, waste control, back-filling and replanting.

Further reading

Geography Senior Four Student's Book, Rwanda Basic Education Board, revised 2026–2027. The national textbook's unit on mining in Rwanda.
Rwanda Mining Investment Pitchbook, Rwanda Mines, Petroleum and Gas Board, 2025. Ten real mining blocks with their geology: practise reading what a mining company reads.
Rwanda State of Environment and Outlook Report 2021, REMA, 2021. Chapter 1 sets out mining's place in the economy and its environmental impacts.
Introductory Mining Engineering, 2nd edition, Howard L. Hartman and Jan M. Mutmansky, Wiley, 2002. A clear university introduction to mining methods, from prospecting to reclaiming the land.

Sources and credits

Sources: RWB urges mining operators to strengthen water pollution prevention measures, Rwanda Water Resources Board, 2026 (Kamonyi investigation, water parameters); Rwanda Disaster Effects Situation Report 2025, MINEMA, December 2025 (mine disasters, lightning, totals); Rwanda State of Environment and Outlook Report 2021, REMA (constraints, environmental impacts, guidelines and standards); Rwanda State of Environment and Outlook Report, REMA, 2009 (Rutongo and Gatumba); Annual Report 2024–2025, MINICOM (prices); Rwanda Statistical Yearbook 2025, NISR (export earnings); Rwanda Mining Investment Pitchbook, RMB, 2025; Mining sector in Rwanda register 30% fall in productivity, RBA news, March 2020 (miners and bank lending); Mining industry of Rwanda, Wikipedia contributors, CC BY-SA 4.0, adapted by Ganzaa (Sebeya suspension, 2012).

Figure 5, the tables and the worked examples were drawn and written by Ganzaa.

Photos: Agriculture just outside the mine and Heating the material to dry, Fairphone, CC BY-SA 2.0, via Wikimedia Commons.

Video: "Mining companies commended for implementing Strategic Environment Assessment", Rwanda Mines, Petroleum and Gas Board (RMB), embedded from YouTube. The rest of the lesson and the exercises were written by Ganzaa.

This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.

1Water samples above and below the mine

2Problems facing mining

3Environmental effects and their mitigation

Water samples above and below the mine

Problems facing mining

Environmental effects and their mitigation