Swimming in Lake Atitlan: Facts and Precautions guatemala

Lake Atitlan is one of Guatemala’s largest lakes, most important tourist destinations, and a national treasure. It’s also a source of drinking water, food, and transportation for an estimated 350,000 people. The lake’s water quality has been in decline for decades due to human impact. These are the facts you should know about the water quality of Lake Atitlan before swimming and, if you swim, where may be safest and precautions to take.

Check out more travel guides, recommendations, and tips on Lake Atitlan and Guatemala.

Facts about water quality

Waste management

The communities in the Lake Atitlan area have limited wastewater treatment infrastructure. As a result, only 20% of sewage is treated. The other 80% is left untreated and discharged directly into the lake.

Pollution

Lake Atitlan suffers from pollution. Pollutants enter the lake from fertilizers, pesticides, deforestation, phosphate detergents used by locals doing laundry in the lake, and trash around the lake basin. When there are storms and heavy rainfall, pollutants and garbage are washed into the lake at a higher rate.

Cyanobacteria blooms

Cyanobacteria blooms occur in Lake Atitlan that are toxic to humans. The two largest cyanobacteria blooms were in 2009 and 2015, but smaller-scale blooms are now happening annually. They are caused by untreated sewage, polluted water that flows from farms and fields, called agricultural runoff, and runoff from local deforestation that enters the lake. As part of a joint initiative between NASA, the U.S. space agency, and the U.S. Agency for International Development (USAID), there is an algae bloom forecasting dashboard you can use, like local authorities do, to monitor the lake’s water quality.

If you’re going to swim

Choose certain areas

Lake Atitlan is a still body of water with no main discharges or outflows, but water quality can vary across different parts of the lake. It’s best to avoid swimming near big villages, like Panajachel, San Pedro, and Santiago Atitlan, where sewage and garbage enter the lake in higher amounts. There are areas locals believe are better for swimming, though this may be based on appearance as opposed to testing. The Cerro Tzankujil nature reserve in San Marcos is considered the best place to swim, while the area around San Marcos and more isolated hotels on the lake are also said to be better than other places.

Take these precautions

  • Ask local guides or hotel staff for the latest updates on water quality. I wouldn’t always trust that people are well-informed, and locals tend to think swimming is fine, but it’s always good to ask.

  • Avoid swimming after a storm or heavy rainfall, which washes pollutants and garbage into the lake.

  • Don’t swim in an area where the water looks discolored, foamy, or smells bad.

  • Don’t swim if you have an open wound or weakened immune system.

  • Keep your head above water if you go into the lake.

  • Don’t ingest the water while swimming.

  • Take a shower right after swimming to help prevent skin rashes or infections.