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The total disappearance of Lake Titicaca is not a real possibility. However, experts point out that its deterioration is advancing rapidly, especially in the shallow shoreline areas directly impacted by human activity. Public policies are proving insufficient, as is the available funding.

ISSUE 140 | 2025

Vesna Marinkovic U.

Lake Titicaca, the most important freshwater lake in South America, has been facing an environmental crisis for several decades now—one that threatens its ecological balance. While claims that the lake could turn into a “sewer” or disappear completely are exaggerated, experts agree that certain areas are severely affected by pollution and the lack of effective environmental management.

According to Xavier Lazzaro, a scientist and longtime expert on the lake, some areas are already seriously deteriorated. The lake’s endorheic nature (meaning it has no outlet to the sea) turns Lake Titicaca into a receptacle that accumulates all the pollution generated within its watershed. He notes that on the Peruvian side, the inner bay of Puno has effectively become a “sewer” due to the collapse of the Espinar Wastewater Treatment Plant (WWTP). As a result, the city’s waste ends up in the lake, worsening its degradation.

On the Bolivian side of the Smaller Lake, Cohana Bay is the most affected area due to the discharge of wastewater from the Katari River basin, which carries waste from El Alto, Viacha, and other nearby cities. Although the Ministry of Environment and Water (MMAyA) has diverted the river’s course, this has simply shifted the problem toward Chojasivi in the municipality of Pucarani and to the islands of Sicuya and Pariti in the northern part of the Taraco peninsula, a shallow region that is more vulnerable to high levels of pollution.

MULTIPLE SOURCES OF POLLUTION

Carlos Revilla, an anthropologist and expert on the Katari Basin, explains that the lake’s deterioration is caused by multiple factors, including pollution from mining waste, sewage, and economic activities that produce large quantities of waste. He states that the municipalities of El Alto, Viacha, Laja, Pucarani, Batallas, and Puerto Pérez contribute to the problem through the massive accumulation of plastic and other solid waste. It is estimated that around 7,000 tons of garbage are dumped into the rivers of the Katari Basin each year, leading to the buildup of kilometers-long stretches of plastic waste up to a meter thick at the Katari River’s mouth, where it flows into Lake Titicaca.

When asked whether the issue of Lake Titicaca is also due to a lack of public policy, Lazzaro responded that the problem goes beyond pollution. It also requires more effective public policies and greater public awareness. He believes it's essential to communicate more broadly about the causes and extent of environmental damage, the viable solutions that combine engineering and nature-based strategies (constructed wetlands, green filters), and the status of projects already completed or under development by the MMAyA.

In fact, he noted that a well-informed society better understands the need to protect ecosystems and enforce regulations. He explained that the lake’s deterioration is a combination of pollution and the effects of climate change, which accelerate phenomena such as eutrophication. This process, caused by an excess of nutrients like phosphorus and nitrogen from human activities, leads to the uncontrolled growth of suspended microalgae in the water column (known as phytoplankton bloom). When these algae die, they consume the water's oxygen, causing massive die-offs of fish, frogs, and even aquatic birds many of which are endemic species, some already endangered.

Carlos Revilla, for his part, added that water management in Bolivia has not followed an adequate watershed approach. He said that while access to potable water has been a priority, wastewater treatment has been neglected. “Currently, only 35% of the water used in the region is treated before being returned to the hydrological system, which worsens lake pollution. Additionally, accelerated urbanization and the large number of economic activities within households make it difficult to monitor and control waste,” he explained.

According to both experts, one of the biggest challenges is the control of industrial and domestic discharges…

STATE AND SOCIETY RESPONSIBILITY

The Ministry of Environment and Water (MMAyA) has implemented some measures to mitigate pollution, but according to both experts, these remain insufficient. They believe that without a change in public behavior and a structural policy for environmental protection, technical solutions alone will not have the expected impact.

They stressed the importance of having all levels of government and the water utility company EPSAS adopt and coordinate a watershed-based approach that goes beyond municipal management. They also called for the implementation of environmental awareness programs at all levels of society, as well as education on environmental protection within school curricula especially in rural areas and stronger regulations to prevent rivers from being used as dumping grounds.

In addition, they agreed on the need to develop strategies to promote cleaner production processes (CPP) within productive units and proper waste management. They emphasized that responsibility lies with society as a whole: to ration and reduce the consumption of goods and water resources, to properly dispose of packaging, to support recycling and composting, and to ensure that only non reusable waste ends up in sanitary landfills.

DETERIORATION

The experts reiterated that the total disappearance of Lake Titicaca is not a real scenario. However, they warned that its deterioration is advancing rapidly, especially in the shallow shoreline areas directly impacted by human activities, which represent only 6% of the lake’s surface. Fortunately, they noted, the pelagic, central, and deeper areas of the Larger Lake (up to 283 meters deep) are still in relatively good condition, with water clarity reaching up to 34 meters.

That said, they believe that pollution, the lack of sufficient, bold, and effective public policies, and the absence of environmental awareness among the population are putting the lake ecosystem’s sustainability and resilience at risk. They argued that it is imperative for the government, industry, and citizens to act together to save this valuable source of life and culture in the Andean region.

For now, they made it clear that pollution in Lake Titicaca has reached alarming levels due to decades of industrial waste, untreated sewage, and the lack of comprehensive and efficient environmental management. As a result, the crisis continues to affect the lake’s biodiversity, as well as the quality of life and health of the communities that depend on its waters. In short, this is a heavily polluted territory of the Bolivian Altiplano.

INSUFFICIENT INFRASTRUCTURE AND TECHNOLOGICAL ALTERNATIVES

The MMAyA, through the Katari Basin Management Unit (UGCK), is working on expanding and modernizing the Puchukollo Wastewater Treatment Plant (WWTP), the most important and currently the only operational plant. However, this facility, completed in 1999, was outdated from the start—designed when El Alto had a population of 450,000, it is now obsolete given the city’s rapid growth, which today exceeds one million inhabitants.

Despite investments aimed at optimizing its operation, the plant is still inadequate, serving only some southern districts of the city. Fourteen other WWTPs are under construction to treat the waters of various rivers in the basin. These include the Tacachira plant in El Alto, which will discharge into the Seque River. However, none of these facilities are fully operational yet. Meanwhile, the absence of a comprehensive system for sewerage, sanitation, and treatment of wastewater and solid waste continues to allow large volumes of contaminated water to reach the lake.

Lazzaro explained that another alternative currently under discussion is the use of compact plants modular systems housed in shipping containers that can be installed without requiring large infrastructure. These units have the advantage of being mobile, allowing for relocation according to needs. Moreover, their design minimizes visual and olfactory impact, making them more acceptable to local communities.

A LONG-STANDING PROBLEM

Revilla pointed out that the crisis of Lake Titicaca is not new. For the past 20 years, communities like Pucarani have been reporting the disappearance of native species such as the mauri, carachi, and the Titicaca frog. He noted that in 2004, during the administration of Carlos Mesa, an emergency law was declared to address the lake’s pollution. Later, between 2013 and 2014, an environmental audit was carried out with the participation of municipalities, the departmental government, and the Ministry of Environment and Water (MMAyA).

In 2015, the Katari Basin Master Plan was launched, with funding of nearly $70 million from the Inter-American Development Bank (IDB). This plan includes the construction of the 14 aforementioned wastewater treatment plants and the expansion of the Puchukollo plant. However, he emphasized that many projects face financial sustainability issues and that funding from international organizations like the IDB remains insufficient given the scale of the problem.

Moreover, they highlighted that social resistance poses another obstacle. Many communities oppose the installation of treatment plants and sanitary landfills in their territories, causing delays in the plan’s execution. Civil society organizations and academia have proposed technical alternatives to mitigate environmental impacts, but the lack of coordination between different levels of government makes the implementation of effective solutions difficult.

INDUSTRIAL AND DOMESTIC DISCHARGES

For Carlos Revilla, one of the biggest challenges is controlling industrial and domestic wastewater discharges. There are around 29,000 economic units that discharge waste directly into rivers and sewers many of them informal and difficult to regulate. While large industries can be more easily monitored, small and medium-sized enterprises often escape state control.

To address this issue, dialogue strategies are being promoted with trade sectors such as meat and leather producers to encourage more sustainable practices. However, in a highly informal environment, changing production habits is a slow and complex process. It can be said that this area is facing dangerous levels of pollution.

For this reason, organizations such as IIADI are proposing and implementing artificial wetlands based on phytoremediation using native species (like totora), water harvesting, green corridors, biochar or microalgae filters, and biobardas to retain floating waste before it reaches the lake. These technologies allow for localized treatment with the collaboration of urban and rural communities, offering a short-term, lower-cost response to mitigate pollution and climate change, with concrete effects on the quality and availability of water for human consumption and agricultural use.

The conclusion of both professionals is that Lake Titicaca is facing an unprecedented environmental crisis as a result of years of pollution and a lack of urban and environmental planning. While both technological and nature-based solutions are being implemented, the sustainability of these efforts depends on effective coordination between the state, civil society, and the international community. Without joint and sustained action, the lake’s future remains uncertain.

THE EXPERTS

Xavier Lazzaro is a French-Bolivian national with a PhD in Biological Oceanography (UPMC, Paris, France) and a PhD in Aquatic Ecology (OSU, Columbus, USA). He served as a scientist at IRD (French National Research Institute for Sustainable Development) for 45 years. Currently, he is an environmental specialist at the Binational Autonomous Authority of the Lake Titicaca, Desaguadero River, Lake Poopó, and Salar de Coipasa Water System (ALT). Since 1979, he has researched the ecological functioning of the Smaller Lake, the mechanisms of eutrophication, and its control. Since 2019, he has designed and coordinated the Lake Titicaca Permanent Observatory (OLT), which monitors hydrometeorological conditions in real time via an automatic buoy, satellite remote sensing, and measurement campaigns at representative locations.

Carlos Revilla is Bolivian, an anthropologist from UMSA, and holds a Master's degree in Development Studies (IHEID - Geneva, Switzerland). He is a professor in the Master's Program on Population and Development at CIDES - UMSA and Director of the Institute for Research and Action for Integral Development (IIADI). He currently implements research and action projects addressing socio-environmental issues in coordination with communities affected by pollution and climate change in the Katari Basin and Lake Titicaca.

“Lake Titicaca is facing an unprecedented environmental crisis, the result of years of pollution and a lack of urban and environmental planning.”