Lake Ypacarai in southern Paraguay was immortalised by the Spanish singer Julio Iglesias. His 1976 ballad Memories of Ypacarai told the story of him meeting a woman next to the blue lake.

History does not relate what happened to the romance, but the lake where they met is no longer blue. In 2013 it made headlines around the world after toxic algal blooms turned it into a vivid green.

As dead fish washed up on its shores, the local ABC newspaper declared that the lake had surrendered after decades of human mistreatment.

Deforested hills

Urbanisation, pollution, deforestation, and poor water management combined with disastrous effect. Some years on, the lake has started to recover following intervention by the national government.

The green has been replaced by a less-alarming murky brown, yet it remains highly polluted. And the lake’s long-term recovery is jeopardised by climate change and continuing human activity along its shores.

Recognising it had a public relations nightmare on its hands which threatened tourism, the government responded to the pollution and algal blooms with a range of measures, including using plants and fish to improve water quality (known as bioremediation), and tougher penalties for polluters.

Monitoring stations were installed, electric canoes and boats were donated to local communities, and dredging the lake was also considered. The algae thrived in the shallow and slow-moving waters of the lake, but its aggressive growth was aided by human activity.

Highly-nutrient fertiliser was washed off surrounding deforested hills and farm land and fed the algae, while unchecked urbanisation along the shore resulted in the washing of sewage and pollution into the lake.

Holiday homes

Tourism is the least of the problems now. It represents a major health crisis for the 800,000 people that live within the lake’s catchment area. As well as dangers posed by human waste and pollutants in the water, the algae itself is toxic.

Studies suggest significant exposure to it increases the likelihood of developing motor neurone disease. Yet, it remains common for local children to swim and play in the lake.

During the summer months of December and January tourists flock to the lake, escaping the stale heat of the capital, Asuncion. The town of San Bernardino on the lake’s eastern shoreline is the primary destination for many of these visitors.

Among the bars and shops that line the main approach to its beach, there is a government-funded information centre about the pollution and the clean-up. But it receives few visitors, even in the height of summer.

Parcels of land across San Bernardino are sold for new holiday homes, while on the outskirts developments of gated holiday villages are appearing.

Torrents of water

The town sits in a 2-km wide strip, hemmed in by the lake to the west and a ridge of hills to the east, meaning it is sprawling northwards and encroaching on wetlands and fields. Tracts of land here are criss-crossed by roads that have been cut through ahead of future development.  

While urbanisation continues to threaten the lake, inadequate sewage infrastructure also means discharges are common during heavy rain. Local hotels ask guests to avoid flushing toilet paper, as it blocks antiquated pipes and often ends up in the lake.  

Climate change is also a culprit in the continued damage to Ypacarai. The temperature of the water is rising, making it more susceptible to algal blooms, while more frequent rain storms in the region are increasing surface runoff and pollution.

A project at the Catholic University of Asuncion analysing changing weather patterns in Paraguay has found the number of severe rain storms at the start of the rainy season in October increased from three in 2013 to twelve in 2017.

During these storms, the distinctive red clay upon which the capital Asuncion sits washes down the streets, choking up what little drainage exists. Some roads have signs advising drivers of a ‘danger zone on rainy days’ where no drainage exists, with torrents of water submerging the carriageway.

Government intervention

This regularly results in the flooding of the poor neighbourhoods and slums that are clustered in the low-lying areas near the city’s Paraguay River.

Although measures locally have begun to improve the water quality of Ypacarai, inadequate investment in infrastructure is a big issue nationally. Paraguay has the second smallest GDP in South America, and fourth lowest levels of foreign direct investment. Its public sector is ranked as the second most corrupt in the region, ahead of only Venezuela. 

Its limited ability to invest in environmental protection and infrastructure, along with its economic dependence on agriculture, livestock, and commodities, makes Paraguay particularly vulnerable to the effects of climate change. It has been estimated that Paraguay could lose 2% of its GDP annually by 2100 because of climate change.

For the foreseeable future the urbanisation of Ypacarai’s shoreline will increase, its surrounding hills will continue to be deforested, and local children will still swim in the polluted waters.

Short of another public outcry if the lake once again returns to a green swamp-like state, it seems unlikely the unrelenting damage inflicted upon it by human activity will cease. And even with the modest success of government intervention, it is unlikely Sr. Iglesias will get to see those magnificent blue waters again.

This Author

Joseph Dutton is a policy advisor for the global climate change think tank E3G. He tweets at @JDuttonUK.