One of the largest glaciers in the Northern Patagonia Ice Field, the Nef Glacier retreat began to reveal its namesake lake in 1945; Nef Lake now stretches more than 2.5 miles/4 km. Nef Lake is one of the tributaries to the Baker River/Rio Baker, Chile's largest river by volume. A hydropower project of five dams across the Baker called HidroAysen was proposed in 2007 and would have flooded 15,000 acres (5,900 hectares) of the natural reserve. Protests and litigation prevented any momentum for its construction, however, and a decade later HidroAysen was cancelled.