Lachay was established as a National Reserve on June 21, 1977 through Law (D.S.) N 310-77-AG. This reserve is rather close to the city of Lima, in the department of Lima, province of Huaura, and it has a surface of 5,070 hectares.

The hillocks are the result of a combination of different factors in the weather of the coast. This is a foggy area because it is placed at the exact altitude where some clouds rest. In Lachay we can see two seasons: the humid one, from June to November, and the dry one, from December to May.

In the first, humid plants get green and have their flowers. In the other dry season they dry and practically disappear from sight. In Lachay there are 74 species of plants, 25 of them menaced by extinction. We can find the mito (Carica candicans), the palillo (Capparis prisca), the tara (Caesalpihia tinctonria) and the nettle (Loasa urens), which covers the reserve of gorgeous yellow flowers.

The most abundant mammals are the coastal wolf (Pseudalopex sechurae) the skunk (Conepatus rex), the mountain mouse (Phyllotis spp.) and the vizcacha (Lagidium peruanum).

In the reserve of Lachay there are about 55 species of birds belonging to 16 families. Among the recorded ones are the owl (Athene cunicularia), the partridge (Nothoprocta pentlandii), the american cernicalo (Falco sparverius peruvianus), and many other species.

Among the reptiles, the most notorious are the jargon, a snake (Bothrops pictus), and the lizard (Migrolophus tigris). The reserve has archaeological sites with cave paintings and other remains of pre-Columbian cultures. Its primordial goals are to restore and preserve the wild flora and fauna in the area.