The National Reserve of Junin was established on August 7, 1974 through (D.S.) N 0750-74-AG, It is to be found in the Pampa of Junin or plateau of Bombom, at 4100 m altitude. It has a surface of 53,000 has which extends in the departments of Junin, province of Junin (districts of Carhuamoyo, Ondores, Junin) and Pasco, province of Cerro de Pasco (districts of Ninacaca and Vicco).

The Junin Lake area is the biggest of the reserve. This lake has a big and rich diversity of birds. The grebe of Junin (Podiceps Takzanowskii) is one of the most important species in the lake that is menaced with extinction. Of the other 36 species it is worthwhile mentioning the sutro duck (Anas flavirustris), the jergo duck (Anas georgica), the puna duck (Anas puna), the huachua (Chloephago melanoptero), the heron (Bubulcus ibis), the pollo de agua or water chicken (Gallinula chloropus), the seagull (Larus serranus), the huaco (Nycticorax), the Flamingo (Phoenicopterus chilensis), the yanavico (Plegadis ridgwayi) and the zambullidor (Pudiceps occidpitalis).

The only wild mammal that lives in the reserve is the guinea-pig, in its wild variety. The Lake Junn is famous for its frogs, such as: Gastrotheca peruana and Pleurodema marmorata, as well as the toad (Bufo spinulosus). As to fishes we have: Orestias elegans and O. empyraeus, called challhua and a Kind of catfish (Tcichomyeterus oroyae).

The vegetation in the borders of the lake is very rich; for example the crespillo (Calamagrostis sp.), the Festuca sp. and Stupa brachyphyla, known locally as ichu. There are many types of reed plants (Juncus andicola). The main purpose of the reserve is the conservation of the flora and fauna that constitute a whole with the Lake Junn.