Brazil

Key Facts

—The deal. Rio de Janeiro signed a three-state accord this week letting São Paulo draw more water from the Paraíba do Sul, the river that runs through all three states.

—The stake. Of the basin’s roughly sixty-one thousand square kilometres, the largest share, about twenty-seven thousand, sits in Rio de Janeiro state.

—The reason. São Paulo’s main Cantareira reservoir system has fallen near a third full in a drought, and the deal is meant to shore it up.