Background:
Lake Atitlán is one of the most important lakes in Central America. The Atitlán watershed is home to approximately 260,000 people, the majority of whom are Mayan. The communities rely on subsistence agriculture, and use the lake for drinking water, transportation, and as a protein source through fisheries. Previous studies in the Lake Atitlán region established the presence of toxic metals and metalloids, pesticides, and indicator bacteria in drinking water and within the lake. Additionally, these communities experience a high prevalence of diarrheal diseases, childhood stunting, chronic illnesses, and various other adverse health outcomes.

Objective:
This pilot project was designed to assess water quality in the Atitlán watershed. Additionally, in connection with a partnered study, breastmilk samples were collected from four towns in the watershed to correlate water contamination with maternal and infant health outcomes.

Methods:
Over a 6-week period in June and July of 2022, 24 water samples were collected from drinking and freshwater sources in the towns of Panajachel, Santiago, San Juan, and San Pedro. Local hotels, restaurants, and community water taps were sampled and analyzed for the presence of _E. coli_ and total coliforms via portable AquaGenX Water Testing Kits.

Results:
Areas with unsafe water contamination were found in each of the four towns. The World Health Organization’s standard for _E. coli_ in drinking water (0 _E. coli_/100 ml) was exceeded in 83% of samples. The most pronounced water contamination was found in Panajachel, where all samples (n=12) had measurable _E. coli_ and 67% of samples contained _E. coli_ concentrations above 100 CFU/100ml.

Conclusion:
The data within this pilot study provide sufficient evidence of contamination to warrant further inquiry into hot-spots of contamination around Lake Atitlán, and the development of collaborative policy actions with local stakeholders.