What Might Work

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This page describes ideas that people are trying or proposing for the lake, and what evidence exists for each. There is no single fix. The ideas below work at different points, from the hillside to the shoreline. For each, we say what kind of evidence we found:

  • Shown here: measured at or near the lake.
  • Reported by the group: what an organization says about its own work, not independently checked.
  • Shown elsewhere: from studies in other places.
  • Idea: plausible, but not tested here.
  • Unknown: we looked and could not find out.

Several of these ideas are disputed; the section “Where people disagree” near the end sets out the main arguments. Local people should decide what is right for San Pedro. This page is a starting point for that conversation, not a plan.

Sunrise light reflected on Lake Atitlán
Sunrise light reflected on the lake.

1. Slow the water on the slopes

The idea: terraces, ditches along the contour (swales), ground cover and trees slow runoff, so less soil and fertilizer wash into the lake.

  • Reported by the group: in 2025 AMSCLAE reported agroforestry on 7.65 hectares with 385 farmers in three towns including San Pedro, and a tree nursery in San Pedro.1 Vivamos Mejor reports planting more than three million native trees and plants in ten years.2 CreaSol was hired to design an eco-park in San Pedro using swales and reeds, though it says the project has stalled.3
  • Shown here (old data): a 2006 field study found farmers on steep plots, some over 40% slope, did little soil conservation.4
  • Unknown: which landowners would take this up, and who would pay.

2. Keep nutrients on the land

The idea: compost, manure and other organic soil-building in place of chemical fertilizer, so nutrients stay in the soil and out of the lake.

  • Shown here: San Pedro’s waste plant makes compost from organic waste for farmers,5 and AMSCLAE says it is promoting organic compost.1 We do not know how many farmers use it.
  • Disputed: a municipal official has said organic farming takes about ten times more labor, while local critics say the municipality itself hands out synthetic fertilizer.6 In 2006 field data, fertilizer was a large part of the cost of growing coffee,4 so there is a money question as well as a labor one. We found no current San Pedro numbers.
  • Reported by the group (nearby region): a development organization working in Sololá and Huehuetenango reports that homemade pest sprays cost about one-sixth as much as industrial pesticides and can cut infestations by up to 90%.7 That concerns pesticides, not fertilizer.
  • Reported by the groups: a company and a local non-profit report that biochar made from human waste raised maize yields about 25% over synthetic fertilizer in trials, and improved tree seedlings’ roots.8

3. Treat water where it is made

The idea: small systems at homes, businesses and neighborhoods, instead of one big plant or pipeline.

  • Reported by the group: a greywater system in Santa Cruz La Laguna (sinks, showers, kitchens) has run since January 2024, serving about 15 families and treating up to 6,000 liters a day through settling tanks and gravel trenches planted with banana plants. No test results have been published.9
  • Shown elsewhere / design: a 2008 paper designed a septic tank followed by a planted underground filter for small basin communities.10
  • Reported by sellers: a Guatemalan seller of biodigester tanks claims over 80% removal of organic load in well-designed systems. It gives no data on nitrogen or phosphorus.11
  • Our caution (an idea, not a finding): tanks like these mainly reduce organic matter and solids. If their output simply soaks into San Pedro’s porous ground, it may not fix the nitrate problem in the groundwater. A sanitary engineer should say.
  • Reported by the group (old): a Guatemalan dry composting toilet design from 1987 produces compost and uses no water. We found no monitoring data.12 Tz’unun Ya’ proposes household biodigesters.13
  • Shown here: San Pedro’s 2025 ordinance requires homes to have wastewater systems.6 What systems count, and who checks, is unknown.

4. Filter at the edge

The idea: planted areas at the shore (reeds and other plants) that catch and use runoff before it reaches the lake.

  • Reported by the group: AMSCLAE plants tul, the native lakeside reed, planting 1,020 linear meters in 2025 (not in San Pedro).14 In 2018 a planting in San Pedro was pulled out by fishermen. The report gives no reason.15 Falling lake levels and an invasive plant have also hurt reeds.14
  • Reported by the group: CreaSol’s eco-park design for San Pedro uses swales and native reeds to filter runoff, and is at an early stage.3
  • Unknown: how much nutrient lakeshore reeds actually remove. In general, planted filters handle organic matter and germs better than nutrients unless designed for them. That is general engineering knowledge, and we have not cited a specific study.

5. Make less waste

  • Shown here: San Pedro banned single-use plastic and Styrofoam in 2016, runs a waste and compost plant, and has monthly shoreline and diver cleanups.16,5,17
  • Local demand: Tz’unun Ya’ asks that companies take responsibility for their packaging waste, and that PET plastic be barred from entering the municipality.16
  • Reported by the researchers: a university lake scientist’s overview suggests using soaps with less phosphorus.18

6. Protect yourself while the lake recovers

Treating drinking water at home does not fix the lake, but it protects people while the lake recovers. In a small 2016 pilot in San Pedro, locally available clay household filters reduced E. coli and removed about 99% of an algae toxin in laboratory tests.19 Checking the lake authority’s alert level before swimming also helps.20 Nitrate in well water is a separate problem that germ filters are not known to solve; see The Lake’s Problems. Practical steps are on What You Can Do.

7. Accountability

The Ministry of Environment’s sanctions against municipalities and 39 criminal complaints about lake contamination are reported to be stalled.21 A public record of alerts, monitoring results and enforcement, with dates and sources, would help people follow what is happening. That is an idea.

Where people disagree

Almost everyone who works on the lake agrees it is polluted and that something has to change. They do not agree on what to do, or on who should decide. We do not pick a side. Most sources are news reports and organizations’ own documents, and we say which is which.

The pipeline proposal (the “megacolector”)

The association Amigos del Lago de Atitlán proposed building sewers in the lakeside towns and a pipeline carrying the wastewater out of the lake’s basin to a treatment plant. A 2018 presentation described 18 sewer networks, 18 treatment plants and an underwater collector for about 275,000 people, at an estimated US$215.6 million.22 An earlier version in 2017 was priced at US$86 million.23

  • Supporters say town treatment plants have not worked. In 2017 Amigos del Lago said fixing the problem with plants would take more than 67 of them, with maintenance costs municipalities do not meet.23 A 2021 paper by two engineers (Stewart Oakley of California State University, Chico, and Pedro Saravia of the University of San Carlos) judged diverting wastewater out of the basin the most sustainable of three options they compared.24
  • Opponents, including leaders from San Pedro La Laguna and the Tz’unun Ya’ collective, say the people who live at the lake were not asked for their consent, and cite Indigenous peoples’ right to be consulted under International Labour Organization Convention 169. They fear that moving the water out of the basin could put control of it in private or agricultural hands.25 San Pedro residents went to Guatemala’s Constitutional Court; reports give the date as 2019 or 2020, and we could not confirm the outcome.25
  • The lake authority said in January 2019 that the collector was one option to be studied alongside others.26
  • We found no statement from Amigos del Lago on the pipeline dated after 2020, and do not know the proposal’s current status.

Big plants or small local systems?

The lake authority’s 2018 count found that only three of 12 treatment plants even sometimes met legal standards.27 Some engineers argue for small systems close to where waste is made, because larger plants fail for lack of money, skills and political support.10 Others favor taking the water out of the basin. Both positions have engineers behind them; the disagreement is partly about technology and partly about who decides.

Fertilizer and the shoreline

The disputes over fertilizer and shoreline works are described under idea 2 and idea 4 above. In short: critics say the municipality distributes fertilizer while banning it near the beach,6 and that it built concrete waterfront walls despite its own ordinance, which an official called an error.6

Who decides?

About 95% of the lake’s roughly 380,000 residents are Indigenous, according to Al Jazeera’s 2021 reporting.25 Several local groups say consultation and decision-making authority matter as much as the engineering. One of the lake’s permaculture designers makes a similar point: the hardest part of restoring the lake, he says, is learning to bring people together.3

What is missing

  • Independent results for any greywater system, biodigester, planted filter, dry toilet or biochar project at the lake.
  • Current numbers for San Pedro’s farm costs, labor and fertilizer use.
  • A reliable split of where the lake’s nutrients come from.
  • The views of fishermen, farmers and neighbors about what would work for them. They are the people who would carry out any of this.

About this page

This page was compiled from public sources in October 2026. It has not yet been reviewed by people in San Pedro,. If you know something we have missed or got wrong, such as a correction, a local study, a group’s work or your own experience, please send it to contact@sanpedrolalaguna.earth. We will read it and add or correct what we can confirm.

Sources

  1. AMSCLAE, “Memoria de labores 2025” (the authority’s own annual report), March 2026. Link
  2. Vivamos Mejor Guatemala, “Impacto” page (the organization’s own figures). Link
  3. Hegarty, N., “The hardest part of restoring a lake isn’t the engineering,” CreaSol Permaculture newsletter, August 3, 2026 (the organization’s own account). Link
  4. Velásquez Samayoa, E., “Costos y rentabilidad de unidades agrícolas (producción de café), municipio de San Pedro La Laguna,” Universidad de San Carlos student field report, 2008 (field data from 2006). Old, small sample. Link
  5. Agencia Ocote, “La procesión de la basura,” February 7, 2023. Link
  6. Prensa Comunitaria, “Reglamento municipal de San Pedro La Laguna para proteger el lago tiene contradicciones,” August 2025. Link
  7. Mongabay, “Ancient Maya knowledge helps Guatemalan farmers cut agrochemical use,” June 9, 2026. Results reported by the organization (World Neighbors); about pesticides, not fertilizer. Link
  8. Vivamos Mejor, “Collaboration between Mosan and Vivamos Mejor” (the organizations’ own report of trial results). Link
  9. Water4Life Global, “Our solutions” (the organization’s own description of the Tzanjomel greywater system). Link
  10. Dobias, J. and Leshem, I., wastewater treatment systems and constructed wetlands in the Atitlán basin, Vatten, 2008. Link
  11. Grupo Artifex, “Biodigestor y Acuerdo Gubernativo 236-2006” (a vendor of these systems; claims not independently tested). Link
  12. “Letrina abonera seca familiar (LASF), Guatemala,” technical description dated 1987 (no field monitoring data). Link
  13. Green Network Asia, “The Tz’ununya’ Collective, Indigenous Mayan Women Who Protect Lake Atitlán.” Link
  14. AMSCLAE, “Conservación y manejo de las zonas litorales del lago Atitlán,” January 2026. Link
  15. AMSCLAE, report on tul management, 2018. Link
  16. La Cuerda (Guatemalan community periodical), “San Pedro la Laguna: acción y propuesta,” December 9, 2022. Link
  17. Prensa Comunitaria, “Mujeres limpian el lago de Atitlán mientras empresas y autoridades evaden responsabilidad,” March 2025. Link
  18. Dix, M. (Centro de Estudios Atitlán, Universidad del Valle), “Problemas ambientales Lago Atitlán,” presentation, March 25, 2014. Link
  19. Roegner, A. et al., household water filters in San Pedro La Laguna, 2016. Peer-reviewed; small pilot; laboratory tests for toxin removal. Link
  20. AMSCLAE (Autoridad para el Manejo Sustentable de la Cuenca del Lago de Atitlán y su Entorno), official website. Link
  21. Ojo con mi Pisto, “Atitlán: 39 denuncias por contaminación siguen varadas en la Fiscalía.” Link
  22. Emisoras Unidas (Guatemalan radio and news), “Presentan propuesta científica para sanear lago de Atitlán,” October 15, 2018. Link
  23. Prensa Libre (Guatemala’s largest daily), “Con millonario proyecto pretenden salvar el Lago de Atitlán,” October 23, 2017. Link
  24. Oakley, S. and Saravia, P., “Manejo integrado de aguas residuales dentro y fuera de la cuenca del Lago Atitlán,” Agua, Saneamiento & Ambiente (Universidad de San Carlos), 2021. Peer-reviewed journal. Link
  25. Aburawa, A., “The grandmother lake: conservation and colonialism in Guatemala,” Al Jazeera, 2021. A major international news outlet; one reporter’s account with named sources. Link
  26. AMSCLAE, “Statement 2019-01,” English translation by Paul Wray. We hold a copy of the statement; we did not locate the original online.
  27. AMSCLAE, “Estrategia de intervención para el manejo de las aguas residuales en la cuenca del Lago de Atitlán,” 2018. The lake authority’s own strategy document. Link