A team of environmental specialists from the Ministry of Water and Environment has launched a three-day investigation into the changing colour of Lake Bunyonyi and growing concerns over water quality supplied to thousands of residents in southwestern Uganda.
The multi-agency team, led by Ms Lilian Idrakua, Commissioner for Water Quality Management, includes experts from the National Environment Management Authority (NEMA), National Water and Sewerage Corporation (NWSC), the Department of Environmental Support Services and the Department of Water Services.
The fresh assessment follows a mysterious incident in August last year when the waters of Lake Bunyonyi changed colour, alarming residents, tourism operators and local leaders.
Speaking during a stakeholders’ meeting in Kabale on Monday, Ms Idrakua said preliminary investigations had ruled out volcanic activity despite the lake’s volcanic origins.
“Although Lake Bunyonyi was formed through lava damming, investigations established that there is no volcanic vent beneath the lake and water temperatures remained within the normal tropical range of between 20 and 25 degrees Celsius,” she said.
According to Ms Idrakua, initial findings pointed to possible environmental stress caused by human activity around the lake, although investigators had not reached a definitive conclusion.
“The initial findings suggested that the phenomenon was more likely linked to human activities around the lake rather than geological processes, although the investigations were not conclusive,” she added.
The latest inquiry comes amid growing fears that unchecked development, poor waste disposal, soil erosion and mining activities in surrounding areas could be degrading one of Uganda’s most important freshwater ecosystems.
Lake Bunyonyi is a major tourism destination and a key water source for thousands of residents in Kabale and neighbouring districts.
Environmental experts are particularly concerned about non-compliance with regulations governing lakeshore developments.
Ms Idrakua said some developers had failed to obtain mandatory permits, conduct annual environmental audits or respect protected shoreline buffer zones.
“Many areas around the lake lack adequate water protection zones, and this accelerates environmental degradation,” she warned.
NEMA erosion mapping data for the Kigezi sub-region estimates that every hectare of degraded land within the lake’s catchment deposits nearly 18 tonnes of soil into the water annually, raising concerns about sedimentation, biodiversity loss and declining water quality.
The ministry team will also reassess the ecological status and depth of Lake Bunyonyi amid long-standing claims about its size and characteristics.
According to recent scientific studies, the lake’s deepest point measures approximately 43.6 metres, with an average depth of about 14 metres, far below the widely circulated but disputed claim that it is Africa’s second-deepest lake at nearly 900 metres.
Beyond the lake itself, investigators are examining complaints about discoloured tap water supplied by NWSC, particularly during morning hours.
Kabale District chairperson Denis Nzeirwe Ndyomugyenyi said protecting the lake was critical for public health and water security.
“We need to safeguard the source of water that serves thousands of people in Kabale and the surrounding areas. The quality of water being consumed by our communities must be guaranteed,” he said.
Kabale Chief Administrative Officer Robert Mugabe described the lake as the backbone of the region’s water supply system and warned that recurring discoloration incidents posed serious concerns.
“The discoloration incident posed a serious threat to public health. We need a comprehensive study because many residents continue to experience discoloured tap water, especially in the mornings,” Mr Mugabe said.
He also called for investigations into changing weather patterns in the Kigezi sub-region, saying environmental shifts could be affecting local water systems.
Kabale Resident District Commissioner [RDC] Maj Godfrey Katamba linked deteriorating water quality to possible gold mining activities near the Rwanda border in Kahungye, Rubaya and Butanda, arguing that runoff from mining operations could be contaminating water sources.
He also blamed poor waste management practices around the lake and urged authorities to strengthen wastewater treatment and environmental protection measures.
“If we do not improve waste management and protect this ecosystem, we risk destroying one of our most important water sources and tourism attractions,” Maj Katamba warned.
The findings of the ongoing assessment are expected to guide future conservation measures and policy interventions aimed at protecting Lake Bunyonyi, one of Uganda’s most iconic natural attractions.