The total disappearance of Lake Titicaca is not a reality. However, experts warn that ...###

The total disappearance of Lake Titicaca is not a reality. However, experts warn that its deterioration is advancing rapidly, particularly in shallow coastal areas directly impacted by human activities. Public policies remain insufficient, as does 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, threatening its ecological balance. While claims that the lake could turn into a "sewer" or disappear completely are exaggerated, experts agree that some areas are severely affected by pollution and the lack of effective environmental management.

According to Xavier Lazzaro, a scientist and long-time specialist in lake studies, some areas are already in a critical state of deterioration. The endorheic nature of its watershed (meaning it has no outlet to the sea) turns Lake Titicaca into a basin that accumulates all the pollution produced within its catchment area. Lazzaro points out that, on the Peruvian side, Puno's inner bay has effectively turned into a "sewer" due to the collapse of the Espinar Wastewater Treatment Plant (WWTP). As a result, waste from the city ends up in the lake, worsening its degradation.

On the Bolivian side, in the Minor Lake sector, Cohana Bay is the most affected area due to wastewater discharges 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 only shifted the problem toward Chojasivi in the municipality of Pucarani and toward the islands of Sicuya and Pariti, located north of the Taraco Peninsula—a shallow-water region that is more vulnerable to high pollution levels.

MULTIPLE POLLUTION FACTORS

Carlos Revilla, an anthropologist and expert on the Katari Basin, states that the lake’s deterioration is caused by various factors, including pollution from mining waste, untreated wastewater, and economic activities that generate large amounts of waste. He notes 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 Katari Basin rivers each year, leading to the buildup of kilometers of plastic waste up to one meter thick at the Katari River’s mouth in Lake Titicaca.

When asked whether the Lake Titicaca crisis also suffers from a lack of public policies, Lazzaro pointed out that the issue extends beyond pollution. He emphasized the need for more effective public policies and greater public awareness. He believes it is essential to communicate more broadly about the causes and extent of environmental degradation, viable solutions that combine engineering and nature-based strategies (such as constructed wetlands and green filters), and the status of both completed and ongoing projects under the MMAyA’s supervision.

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 like eutrophication. This process, driven by excess nutrients such as phosphorus and nitrogen from human activities, causes uncontrolled microalgae growth in the water column (known as phytoplankton blooms). When these algae die, they consume the water’s oxygen, leading to mass deaths of fish, frogs, and even aquatic birds-many of which are endemic species, several of them endangered.

For his part, Carlos Revilla added that water management in Bolivia has not followed an adequate basin-wide approach. He argued that while access to drinking water has been prioritized, wastewater treatment has been neglected. "Currently, only 35% of the water used in the region is treated before being returned to the hydrological system, worsening the lake’s pollution. Additionally, rapid urbanization and the high number of economic activities taking place in domestic spaces make it difficult to monitor and control waste disposal," he explained.

“For Both Experts, One of the Biggest Challenges Is Controlling Industrial and Domestic Waste 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 efforts remain insufficient. They believe that without a change in public habits and a structural environmental protection policy, technical solutions will not have the expected impact.

They emphasized that it is crucial for different levels of government and the EPSAS company to adopt and coordinate a watershed approach that goes beyond municipal management. This should include implementing environmental awareness programs at all levels of society, integrating environmental protection education into school curricula-particularly by allocating more resources to rural areas—and strengthening regulations to prevent rivers from being used as dumping sites.

Additionally, they agreed that strategies must be developed to promote cleaner production processes (CP) in industrial facilities and ensure proper waste management. They stressed that responsibility lies with society as a whole to ration and reduce the consumption of goods and water, properly dispose of packaging, encourage recycling and composting, and ensure that only non-recyclable waste is sent to landfills.

DETERIORATION

The experts reiterated that the total disappearance of Lake Titicaca is not a real threat. However, they highlighted that its deterioration is advancing rapidly, particularly in shallow coastal areas directly impacted by human activities, which account for only 6% of the lake's surface. Fortunately, they noted, the pelagic, central, and deep zones of the Greater Lake (reaching depths of up to 283 meters) are still in good condition, with water transparency reaching up to 34 meters.

Nevertheless, they warned that pollution, insufficient and ineffective public policies, and the lack of environmental awareness among the population are putting the lake’s ecosystem sustainability and resilience at risk. They stressed the urgency for the government, industry, and citizens to act together to save this invaluable source of life and culture in the Andean region.

For now, they made it clear that Lake Titicaca’s pollution has reached alarming levels due to decades of industrial waste, untreated sewage, and the absence of a more comprehensive and efficient environmental management system. Consequently, the crisis continues to impact the lake’s biodiversity, the quality of life, and the health of the communities that depend on its waters. This makes it one of the most heavily contaminated areas in the Bolivian highlands.

INSUFFICIENT INFRASTRUCTURE AND TECHNOLOGICAL ALTERNATIVES

Despite investments aimed at optimizing its performance, the plant remains insufficient, as it only serves certain southern districts of the city. Fourteen additional WWTPs are currently under construction to treat wastewater from various rivers in the basin, including the Tacachira plant in El Alto, which will discharge into the Seque River. However, none of these plants are yet fully operational. Meanwhile, the lack of an integrated sewage, sanitation, and solid waste management system continues to allow large volumes of contaminated water to flow into the lake.

Lazzaro explained that another alternative under discussion is the use of compact plants—modular systems housed within shipping containers that can be installed without requiring large infrastructure. These units have the advantage of being mobile, allowing for easy relocation based on needs. Additionally, their design minimizes visual and odor impacts, making them more acceptable to local communities.

A LONG-STANDING PROBLEM

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

In 2015, the Katari Basin Master Plan was launched, with financing of nearly $70 million from the Inter-American Development Bank (IDB). This plan includes the construction of the 14 treatment plants mentioned earlier, as well as the expansion of the Puchukollo plant. However, Revilla pointed out that many projects face financial sustainability issues and that resources from international organizations such as the IDB remain insufficient given the scale of the problem.

Additionally, social resistance has been highlighted as another major obstacle. Many communities oppose the installation of treatment plants and sanitary landfills in their territories, leading to delays in the plan’s execution. Civil society organizations and academic institutions have proposed technical alternatives to mitigate environmental impacts, but a lack of coordination between different levels of government hinders the implementation of effective solutions.

INDUSTRIAL AND DOMESTIC WASTE DISCHARGES

For Carlos Revilla, one of the biggest challenges is controlling industrial and domestic waste discharges. There are approximately 29,000 economic units that discharge waste directly into rivers and sewers, many of which operate informally and are difficult to regulate. While large industries can be monitored more easily, medium and small enterprises often evade state control.

To address this issue, strategies are being promoted through dialogue 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, making this region one of high-risk contamination.

For this reason, organizations such as IIADI are proposing and implementing artificial wetlands based on phytoremediation with native species (such as totora reeds), rainwater harvesting, green corridors, biochar or microalgae filters, and biobarricades to trap floating waste before it reaches the lake. These technologies enable localized treatment in collaboration with urban and rural communities, providing a low-cost, short-term response to pollution and climate change while delivering tangible benefits to water quality and availability for human consumption and agricultural use.

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

THE EXPERTS

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

Carlos Revilla is a Bolivian anthropologist from UMSA. He holds a Master’s degree in Development Studies (IHEID - Geneva, Switzerland). He is a professor in the Master's Program in Population and Development at CIDES - UMSA and the Director of the Institute for Research and Action for Integral Development (IIADI). He currently leads research and action projects on 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.”