Countdown to the Guarani Aquifer Agreement coming into force: will it be effective in promoting transboundary groundwater governance?

The following essay is by Pilar Carolina Villar, Professor of Environmental Law at Federal University of São Paulo. She can be reached at pcvillar [at]

The signing of the Guarani Aquifer Agreement (Portuguese / Spanish / English [unofficial]) on August 2, 2010, by Argentina, Brazil, Paraguay and Uruguay was received by the water community with excitement due to the few number of treaties dedicated to transboundary aquifer cooperation, the absence of a water conflict, and the short time it took to secure the signatures after the end of the Guarani Aquifer System Project. In 2012, Argentina and Uruguay ratified the treaty with the promulgation of Law n° 26.780/2012 and Law n° 18.913/2012, respectively. Thereafter, the Agreement faced a period of stagnation until May 2017 when Brazil ratified it with Legislative Decree n° 52/2017. Almost a year later, in April 2018, Paraguay ratified the Agreement when it approved Law nº 6037/2018.

After almost 8 years, the Agreement is in the final stage of coming into force, although Paraguay has yet to deposit its instrument of ratification with Brazil, which is the official depository for the Agreement. According to Article 21, the Agreement will officially enter into force on the thirtieth day after that deposit occurs.

Schematic hydrogeological map of the Guarani Aquifer System. Source: The Guarani Aquifer Initiative – Towards Realistic Groundwater Management in a Transboundary Context, Case Profile Collection Number 9. Sustainable Groundwater Management: Lessons from Practice (Nov. 2009)

The Agreement’s ratification by the four countries represents a new phase in the process of cooperation among the Guarani countries. It allows implementation of the Guarani Aquifer Commission, and the possibility of restarting cooperative projects that will promote the development of knowledge and management of the Guarani Aquifer System. However, considering the long ratification process of the Agreement and the role of other transboundary water organizations in the La Plata Basin, should we be optimistic in the context of transboundary aquifer cooperation?

In view of the lack of international agreements for the joint management of transboundary aquifers, the ratification of the Agreement represents a milestone to encourage more countries in South American to include groundwater cooperation in their practice of international affairs. Moreover, the ratification opens a path for the establishment of a common institutional arrangement dedicated exclusively to groundwater issues among the four countries. The existence of an international agreement could also be used as a positive force for attracting international funds from organizations like the Global Environment Fund, World Bank, Organization of American States, UN Environmental Programme, and UN Development Programme, which may be interested in supporting the operationalization of the only international groundwater cooperative arrangement in South America. Finally, the Guarani Aquifer States could become more interested in promoting cooperative projects and actions regarding the aquifer since the Agreement will soon be binding on all of them.

The future of the Guarani Aquifer Agreement is dependent especially on the will of the countries to enforce the agreement’s institutional framework. On this point, the projections are not necessarily encouraging. While the Guarani Aquifer Commission is the pillar of the Agreement, it is unclear what its powers will be or whether it will have legal personality under international law. Moreover, it is impossible to foresee when the countries will establish the Statute of the Commission. Regardless, it does not seem to be a priority in the short term, especially considering the current political and economic conditions of the Guarani countries.

Even with the Guarani Aquifer Commission, cooperation should not be taken for granted. The La Plata Basin has a complex institutional system made up of fourteen organizations that have legal personality under international law and four technical committees. All of them face difficulties in consolidating themselves as leading players in cooperation over the La Plata basin. In fact, the amount of institutions contrasts with the relatively low number of joint actions and products resulting from their work. Even the Intergovernmental Coordinating Committee of the Countries of the Plata Basin, which is the oldest water-related organization in the La Plata Basin area, still has problems receiving financial support from its member countries, and largely depends on international funds to conduct studies in the basin. As a result, the Guarani Aquifer Commission runs the risk of becoming another water-related organization with very limited influence.

Implementation of the Agreement and creation of the Guarani Aquifer Commission could benefit from the existence of CeReGAS – Centro Regional para la Gestion de Aguas Subterráneas (Regional Center for the Management of Groundwater), an international center located in Montevideo, Uruguay, that is dedicated to promoting groundwater management and cooperation in the regional context. While CeReGAS and the Guarani Aquifer Commission have different mandates, since the first is a regional center supported by UNESCO and the other is an organization established by an international treaty restricted to the Guarani Aquifer countries, they might build an alliance to optimize funding and technical resources. Their scope is closely related since both focus their efforts on the promotion of groundwater cooperation, one in the South American context while the other in the Guarani Aquifer region. CeReGAS has also developed a case study on the Guarani Aquifer, and has produced documents on and disseminated the results of the Guarani Aquifer System Project.

The Agreement soon will come into force and become a binding instrument for the Guarani Aquifer States. However, the questions of when and how it will be implemented remain unanswered. The challenges to applying the Agreement are some of the same facing other water agreements in the region: overcoming the tendency of building fragile water-related institutions, improving cooperation between institutions or between States, expanding transparency in actions of cooperation, and guaranteeing financial support. In this sense, the first step for the countries involved is to establish the Commission and define its capacity, a mission that could be facilitated by the presence of CeReGAS. Then, the States involved must overcome the traditional challenges related to political will, institutional capacity and efficiency, as well as the provision of funds to support the Commission and the execution of cooperative projects. Only time will tell if the Guarani Aquifer States will cooperate successfully over the joint management of the Guarani Aquifer.

One Response to “Countdown to the Guarani Aquifer Agreement coming into force: will it be effective in promoting transboundary groundwater governance?”

  1. Francesco Sindico says:

    Dear Pilar,

    thanks for your excellent analysis! Just wanted to share the official page from the Paraguayan government related to its ratification and a link to a free article that I have co-authored with Ricardo Hirata (USP) and Alberto Manganelli (CEREGAS), organisation that you mention in your blog. In the paper I co-authored we also put emphasis on what a Guarani Aquifer Agreement in force (we wrote this before its entry into force) could lead to in relation to future management of the aquifer. The article can be downloaded for free at and is part of a special issue on transboundary aquifers, which will be promoted once all articles are published.

    Francesco Sindico
    Co-Director of the Strathclyde Centre for Environmental Law and Governance