María looked at the clogged, stinking streams and started knocking on doors

María Monges was 61 when she decided her neighborhood could not wait for rescue. After floods kept dragging sewage, trash and worse into Costa Esperanza, on the banks of the Reconquista — Argentina's second-most-polluted river — she went door to door until her neighbors picked up shovels beside her. That was more than twenty years ago. Today she leads the 9 de julio cooperative, which cleans the river's streams five days a week, and researchers say women like her are the backbone of the whole effort. The Reconquista runs 51 miles through 18 municipalities, past the homes of four to five million people, and has been fouled by untreated sewage and industrial waste since the 1970s. It is still a long way from clean — but residents say the skin problems that once plagued children are getting rarer, and Monges has no plans to stop.