Lago Peñuelas National Reserve is a national reserve of Chile. The reserve was created around Peñuelas Lake, a freshwater reservoir that provides drinking water to Valparaíso and Viña del Mar. The park, which is located in the Valparaíso Region of Chile, was declared a protected area in the year 1952 in order to protect the drainage of the Peñuelas reservoir and dam, built at the end of the 19th and beginning of the Twentieth century. The park, along with La Campana National Park to its north, was designated Campana-Peñuelas Biosphere Reserve by UNESCO in 1984.