Lake Titicaca, shared by Bolivia and Peru at 3.809 meters above sea level, shows unequivocal signs of deterioration: in its shallow areas, fishing has collapsed and many families have begun to leave, a reality that shows that pollution advances without stopping in the highest navigable body of water on the planet.
The scientific community warns that the window for action is limited and that, if no action is taken now, reversing the damage could become technically unfeasible in less than a decadeThe degradation is especially acute in the so-called "smaller lake," where the combination of spills and recent droughts is leaving the water level at its limit.
Where it worsens: the 'lesser lake' and Cohana Bay
The smaller lake, separated from the larger lake by the Strait of Tiquina, covers about 2.000 square kilometers and is the most vulnerable area of the system. Its deepest part is around 40 meters, but in large sections the water table barely reaches 2-4 meters, with records of only 50 centimeters in places like Cohana during recent dry years; the larger lake, on the other hand, exceeds 6.000 square kilometers and retains greater depths.
Cohana Bay has become the epicenter of the problem because the Katari River, which concentrates urban, industrial, and mining wastewater from El Alto (almost one million inhabitants) and neighboring Viacha. This pollution corridor pushes nutrients and other compounds into the smaller lake.
On the surface, green carpets of nutrient-fed microalgae appear, while at the bottom, a blackish material accumulates and adheres to the totora stems; this crust and the penetrating smell are symptoms of eutrophication and the loss of ecological quality of the water.
Until recently, it was common to see nets searching for native species such as karachi or mauri; today, this sight is rare. The water has become darker, and the unpleasant smell persists, signs of a process that suffocates fish, frogs and birds in the most impacted sectors.
On the shores, community leaders describe a silent exodus: young people are leaving because fishing no longer supports their families, and income from totora reeds and crafts is dwindling. The story is repeated at the lake's edge: pollution It extends from Cohana to other communities and the deterioration gives no respite.
Causes and processes that cause water to suffocate
Research by the Lake Titicaca Binational Authority points to a combination of urban waste, industrial discharges, and mining activity. Phosphorus from detergents fuels microalgae blooms that, when decomposed by bacteria, reduce dissolved oxygen and generate hydrogen sulfide, a compound capable of killing aquatic fauna and birds.
The droughts of recent years have aggravated the situation by lowering water levels and concentrating pollutants, especially along the shoreline of the smaller lake, where human pressure and shallow waters intersect. Residents on several shores say the effects are becoming increasingly noticeable. further from Cohana Bay, with murky waters and expanding swampy areas.
Social impact: communities that are emptying
The island of Sicuya, the smallest in Titicaca, is a mirror of the crisis: it has less than 300 inhabitants, accessible only by boat, and a school with 27 students. Many houses remain closed for much of the year because their owners have emigrated in search of opportunities.
The reeds, vital for livestock and crafts, appear with dark spots that animals avoid; with fishing at a minimum, the deterioration of this resource multiplies the economic damage and forces more families to leave. In everyday terms, life “no longer yields” on the shore like before.
The health dimension is worrying: social organizations warn of gastrointestinal, renal and hepatic risks, and even neurological effects in children linked to the presence of heavy metals. Tributaries on the Peruvian side, such as the Coata River, are also noted, which contribute untreated water to the system.
Scientific alert and window for action
El investigador Xavier Lazzaro (ALT) He argues that there are no more than ten years to halt the trend, focusing on the smaller lake. In his proposal to "save Lake Titicaca," he emphasizes that the source of phosphorus must be attacked and nutrients prevented from continuing to enter the water.
Among the notable measures are completing 14 treatment plants to reinforce the main station, deploy mobile "mini-plants" the size of containers, build a large interceptor channel to divert contaminated flows before reaching the lake and create shallow lagoons with reeds that act as as natural filters.
Furthermore, it is proposed to curb the uncontrolled expansion of El Alto towards the lake through urban planning and promote responsible tourism that contributes to conservation. There are replicable experiences: the lakes Lemán (Switzerland) and Paranoá (Brazil) They managed to improve their quality with policies sustained over decades.
Obstacles and what remains to be done
On the ground, progress is coming slowly: modernization of the main plant The country is experiencing delays, and various projects have not achieved the expected effectiveness. Organizations such as Fundación Tierra warn of shortcomings in public mitigation and call for accelerated investment and oversight.
Beyond the rough work, binational coordination, spill control, mining oversight, and environmental education are needed. School initiatives such as "El Titicaca nos cuente" (Titicaca Tells Us) and outreach programs are calling for more information. WWTP, recycling and campaigns water care to protect the most vulnerable communities that depend on the lake.
The landscape of the smaller lake is that of a cornered ecosystem, with Cohana as the thermometer of a crisis that requires cutting phosphorus at its source, completing water treatment, regulating urban expansion, and strengthening monitoring of mining activity; only with sustained and shared action will this be possible. reverse degradation before the technical window closes.