event 24 Sep 2021

Nexus Blog // In a remote Andean village in Peru, Nexus connects an ancestral lagoon, guinea pigs and solar energy

This article presents a demonstration project of the Nexus Regional Dialogue in Latin America and the Caribbean (LAC), co-financed by the European Commission and the Federal Ministry for Economic Development and Cooperation. Bringing together ancestral water sources with solar power, crops and livestock, the project seeks to build food security and prosperity in San Pedro de Casta, Peru, through a practical demonstration of the water, energy and food security (WEF) Nexus approach.

category Nexus Blog tag Water plan tag Food and Agriculture tag Water tag Irrigation tag Food tag Solar-powered Irrigation Systems (SPIS) globe Americas globe Latin America and the Caribbean globe South America
E7 A8538 Plaza de armas de San Pedro de Casta credits Aquafondo

Main square of San Pedro de Casta. © AQUAFONDO

San Pedro de Casta is a small village in the upper Santa Eulalia river basin 3,000 metres above the central coast of Peru, in the department of Lima. The community will soon be in the spotlight as the site of a multifaceted Nexus project, bringing together ancestral water sources with solar power, crops and livestock. The project seeks to build food security and prosperity in San Pedro de Casta through a practical demonstration of the water, energy and food security (WEF) Nexus approach.

The village owes its existence to a complex pre-Hispanic water system in which potatoes, maize, barley and beans grow with water from a spring that is partly fed by an ancestral lagoon (a qocha), approximately six kilometres away in the mountains. Unfortunately, the lagoon’s 69-metre-long stone wall is in disrepair, and in combination with advancing climate change, the reduced water supply threatens the community’s already limited food production.

Project location
Project location

The Nexus Regional Dialogues (NRD) Programme, jointly funded by the European Commission and the Federal Ministry for Economic Development and Cooperation (BMZ), identified this project opportunity back in 2018 in an extensive search for proof-of-concept ideas throughout the hemisphere to show the WEF Nexus approach in action. At that stage, the identified project focused solely on the rehabilitation of the lagoon and the construction of levee. In the last year, however, the search for Nexus demonstration projects was reactivated, and the San Pedro de Casta Project gained renewed interest with a new perspective. The Water Fund for Lima and Callao - AQUAFONDO, was selected for the implementation of the project, being very familiar with the community and has previous experience in project implementation with GIZ, so it is well placed to make valuable contributions to the project.

Fresh ideas for an ancestral lagoon

From the WEF Nexus perspective, rehabilitation of the ancestral lagoon is only the beginning of what the project can achieve. Once restored, the reliable water supply will be connected with a communal ‘bio-orchard’ on the edge of the village. Here, in the warmth of a 240-square-metre greenhouse, a share of the water will flow through drip irrigation to a diverse seasonal rotation of vegetables, ranging from broccoli and beets to the much needed tomatoes.

While vegetables will flourish inside the greenhouse, alfalfa and green forage maize will be irrigated outside with sprinkler irrigation system fed with water from the rehabilitaed reservoir. These crops will feed a small herd of guinea pigs raised in a 100-square-metre shed nearby. An indigenous livestock species and a delicacy throughout the region, guinea pigs are rich in proteins, amino acids and essential fatty acids that are otherwise often lacking from people’s diets. They will therefore represent a valuable contribution to the food security and adequate nutrition of the village.

Solar energy and circular nutrients

A Nexus point of view cannot ignore the energy needs of these activities. The guinea pigs need lighting in their shed for nighttime management. While San Pedro de Casta does have electricity, the supply only meets residential users, and it is sometimes cut off to the whole village . Hence, the project will provide lightening for the guine pig shed through solar panels that will maintain reliable power without incurring costs to the grid.

Soon, as the project produces vegetables and guinea pigs, it will also generate their waste products: crop residues and guinea pig droppings. These present an opportunity to make the project more circular – a key priority in the WEF Nexus approach. A compost plant on site will turn these inputs into organic fertiliser. Rather than going to waste, the composted material will bring nutrients back into the greenhouse to enrich the next harvest of vegetables.

Welcome of the participants before the visit of the lagoon. © AQUAFONDO
Welcome of the participants before the visit to the implemented projects. © AQUAFONDO

To the table and the market

By incorporating water, energy and food security in a circular design, the restored ancestral lagoon, communal bio-orchard, guinea pig shed, solar panels and composting plant will contribute to the diets and prosperity of San Pedro de Casta. They will be managed by a representative committee that will ensure that all households can purchase vegetables and guinea pigs at low prices. As production goes beyond household needs, it will be taken to market, a new source of income for the village.

All of this lies ahead, as the project is gearing up to start in September 2021. The first steps will be a detailed baseline survey of the community and the start of a series of capacity building activities. Throughout the establishment of the bio-orchard and guinea pig production, AQUAFONDO will lead workshops to build knowledge about household nutrition, guide business planning for the wider marketing of products, and support women in the community to participate and lead. The residents of San Pedro de Casta will have many opportunities to engage with their project, to enjoy its outputs, and through it, to be part of a worldwide dialogue on better ideas for using water, energy and food resources.

La versión en español de este artículo está disponible aquí.

Further information


GIZ Peru


Project description (in Spanish)


E7 A8538 Plaza de armas de San Pedro de Casta credits Aquafondo

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Tina Schmiers


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