SAN SALVADOR, El Salvador (AP) — One of Central America’s longest rivers will be the primary beneficiary of El Salvador’s deal to refinance $1 billion of debt with support from the U.S. government amid a resurgence in so-called debt-for-nature swaps.

In the deal announced by both governments this week, El Salvador committed the $350 million it will save to conservation projects benefiting the Lempa River, which provides two-thirds of the country’s water supply.

Jorge Oviedo of the non-governmental organization Environmental Investment Fund of El Salvador, said the agreement would “improve people’s lives and support the climate resilience that we need as Salvadorans.” His organization will partner with Catholic Relief Services to manage the program.

The Lempa River’s headwaters are in Guatemala and it flows through Honduras en route to El Salvador where it empties into the Pacific Ocean.

“I describe it as the heart and lungs of the country,” said the Catholic Relief Services’ Paul Hicks, interim program director for the Rio Lempa Conservation and Restoration Program. The Lempa provides not only drinking water, but also hydroelectric power, as well as water for agriculture and industry.

The river’s watershed is threatened by deforestation and unsustainable agricultural practices, Hicks said. Some of the tributaries have gone dry from too much water being diverted and very little of the water used for industry or sanitation is treated.